Need help fuel system issues

[Zackattack]

Hello all,

The other day I was driving and i felt what i thought was a miss when I hit the gas. A few more times I thought i felt it on my way home but then just thought I was crazy. Next day I started the car, it ran terribly and shut off. I had one code that said the fuel pump control module was shorted to ground. I got another one and installed it. Same thing. Put the old one back in and cranked it a bunch to get some data and got a bunch of stuff from VCDS.

Is it ok to post the entire scan log? Not sure what's ok to post. Anyways here's some of the data:

Voltage terminal 30: 11.591 V (obviously low from all the cranking)

14627 - Fuel Pump Control Module
P025A 00 [10100111] - Electrical Fault
MIL ON - Not Confirmed - Tested Since Memory Clear

2636 - Low Pressure Fuel regulation
P310B 00 [01100101] - Fuel Pressure Outside Specification
Not Confirmed - Tested Since Memory Clear

00771 - Fuel Level Sensor (G)
010 - Open or Short to Plus - Intermittent

00438 - Fuel Supply Sensor 2 (G169)
010 - Open or Short to Plus - Intermittent

02616 - Fuel Tank Cap; Unlock
009 - Open or Short to Ground - Intermittent

02615 - Fuel Tank Cap; Lock
009 - Open or Short to Ground

We've had an insane cold winter. Since January it hasn't got above 20 degrees F much at all. Maybe a day here and there until now. My courtesy entry on my doors also stopped working about a month ago and I have faults for that and central locking. Just today when I was scanning VCDS was saying it couldn't detect the vin, although in the auto scan it did bring back the VIN but in engine functions it couldn't detect it. I'm assuming the wiring harness for this runs inside the car to the instrument cluster? I'm really trying to avoid swapping anymore parts until I can figure out what the cause is. Any help is appreciated! Does anyone have the wiring diagram for this or do I have to spend $30 on alldata again?

Zach

[Zackattack]

I should note. In the weeks prior to this not only did the touch sensors stop working on the rear door but then the rear door started making crazy noises when in reverse and then I got a fault for the child lock control on the rear driver door. After all that this happened. Not sure if its related but here's the full scan:

Chassis Type: FL-AU48 (8R0)
Scan: 01 02 03 05 08 09 15 16 17 19 36 42 44 46 47 52 53 56 5F 62
6C 72

01-Engine -- Status: Malfunction 0010
02-Auto Trans -- Status: OK 0000
03-ABS Brakes -- Status: Malfunction 0010
04-Steering Angle -- Status: OK 0000
05-Acc/Start Auth. -- Status: Malfunction 0010
08-Auto HVAC -- Status: OK 0000
09-Cent. Elect. -- Status: OK 0000
15-Airbags -- Status: OK 0000
16-Steering wheel -- Status: OK 0000
17-Instruments -- Status: Malfunction 0010
19-CAN Gateway -- Status: Malfunction 0010
36-Seat Mem. Drvr -- Status: OK 0000
42-Door Elect, Driver -- Status: Malfunction 0010
44-Steering Assist -- Status: OK 0000
46-Central Conv. -- Status: Malfunction 0010
47-Sound System -- Status: OK 0000
52-Door Elect, Pass. -- Status: OK 0000
53-Parking Brake -- Status: OK 0000
56-Radio -- Status: OK 0000
5F-Information Electr. -- Status: OK 0000
62-Door, Rear Left -- Status: Malfunction 1010
6C-Back-up Cam. -- Status: OK 0000
72-Door, Rear Right -- Status: OK 0000
-------------------------------------------------------------------------------
Address 01: Engine (DET-CPMB) Labels: None
Part No SW: 8K5 907 115 J HW: 8K2 907 115 L
Component: 2.0l R4/4V TF H09 0002
Revision: ECH09--- CVN: 68252F0B
Coding: 4A2A0013242600062000
Shop #: WSC 43665 000 1048576
ASAM Dataset: EV_ECM20TFS0118K5907115J 001003
ROD: EV_ECM20TFS0118K5907115J.rod
VCID: 392F2DF919DA6C1250D-806C
VINID: 9D195659159C19578000900310F6687C77

2 Faults Found
14627 - Fuel Pump Control Module
P025A 00 [10100111] - Electrical Fault
MIL ON - Not Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Priority: 2
Fault Frequency: 1
Mileage: 291842 km
Date: 2025.03.05
Time: 18:20:36

Engine RPM: 0.00 /min
Normed load value: 0.0 %
Vehicle speed: 0 km/h
Coolant temperature: 30 °C
Intake air temperature: 12 °C
Ambient air pressure: 940 mbar
Voltage terminal 30: 11.591 V
Unlearning counter according OBD: 40
Fuel pump: specified value: 10.001 %
Low fuel pressure: specified value: 600.0 kPa
Fuel temperature: 30.0 °C
Fuel pump adaptation: 3.9 kPa
High fuel pressure: specified value: 8.9600 MPa

2636 - Low Pressure Fuel regulation
P310B 00 [01100101] - Fuel Pressure Outside Specification
Not Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Priority: 2
Fault Frequency: 1
Mileage: 291842 km
Date: 2025.03.05
Time: 18:18:45

Engine RPM: 1276.50 /min
Normed load value: 30.6 %
Vehicle speed: 0 km/h
Coolant temperature: 15 °C
Intake air temperature: 12 °C
Ambient air pressure: 940 mbar
Voltage terminal 30: 13.240 V
Unlearning counter according OBD: 40
Engine status: COENG_RUNNING
Engine oil temperature: 12.0 °C
Engine operating condition-Channel 87: Idle
Relative load value: 48.07 %
Current system status: SYC_DRIVE
Engine torque: 57.6 Nm

Readiness: 1110 0101

-------------------------------------------------------------------------------
Address 02: Auto Trans (J217) Labels:* Redir Fail!
Part No SW: 8K0 927 158 T HW: 0BK 927 156 AL
Component: 0BK 20TFSIUSA H16 1003
Revision: --H16--- CVN: 17DA5374
Coding: 000002
Shop #: WSC 00000 000 00000
ASAM Dataset: EV_TCMAL551211 002020
ROD: EV_TCMAL551211_002_AU48.rod
VCID: 47CB5B015F2E0AE2D69-8012

No fault code found.

-------------------------------------------------------------------------------
Address 03: ABS Brakes (J104) Labels:. 8K0-907-379-V2.clb
Part No SW: 8K0 907 379 CF HW: 8K0 907 379 CF
Component: ESP8 quattro H09 0050
Revision: -------- Serial number: --------------
Coding: 2D1D1801
Shop #: WSC 02391 785 00200
VCID: 7F5B03E147FE82222E9-802A

1 Fault Found
02214 - Tire Pressure Warning
000 - - - Intermittent
Freeze Frame:
Fault Status: 00100000
Fault Priority: 1
Fault Frequency: 1
Reset counter: 116
Mileage: 290623 km
Time Indication: 0
Date: 2025.02.12
Time: 16:55:35

Freeze Frame:
Hex Value: 0x6900
Hex Value: 0x4006
Hex Value: 0x1221
Hex Value: 0x1FB3
Hex Value: 0x0000


-------------------------------------------------------------------------------
Address 05: Acc/Start Auth. (J393) Labels: Redir Fail!
Part No SW: 8K0 907 064 GM HW: 8K0 907 064 FM
Component: BCM2 2.0 H12 0633
Revision: 00002001
Coding: 0D814040000000000000
Shop #: WSC 02391 785 00200
VCID: 015F8519310AF4D258D-8054

Subsystem 1 - Part No SW: 8K0 905 852 E HW: 8K0 905 852 E
Component: J764 ELV MLB H40 0046
Serial number: 2313000122084003

2 Faults Found
00192 - Rear Left Door Handle Touch Sensor (G417)
011 - Open Circuit
Freeze Frame:
Fault Status: 01101011
Fault Priority: 2
Fault Frequency: 1
Reset counter: 28
Mileage: 289412 km
Time Indication: 0
Date: 2025.01.07
Time: 09:51:01

01330 - Central Control Module for Central Convenience (J393)
013 - Check DTC Memory - Intermittent
Freeze Frame:
Fault Status: 00101101
Fault Priority: 6
Fault Frequency: 22
Reset counter: 147
Mileage: 291139 km
Time Indication: 0
Date: 2025.02.22
Time: 11:27:12


-------------------------------------------------------------------------------
Address 08: Auto HVAC (J255) Labels: None
Part No SW: 8K1 820 043 T HW: 8K1 820 043 T
Component: KLIMA 3 ZONEN H04 0121
Revision: C1000000 Serial number: 01150720130747
Coding: 6480208000
Shop #: WSC 02391 785 00200
VCID: 392F2DF9195A6C1250D-806C

No fault code found.

-------------------------------------------------------------------------------
Address 09: Cent. Elect. (J519) Labels:. 8K0-907-063.clb
Part No SW: 8K0 907 063 DH HW: 8K0 907 063 DH
Component: BCM1 1.0 H16 0103
Revision: 08016001 Serial number: 00000646047302
Coding: 26000091863CAFC00000480300003D0D0F1C5308A209022100 0008004000030100000030000000
Shop #: WSC 02391 785 00200
VCID: 78A9E8FD62D0B51A6F3-802C

Subsystem 1 - Part No SW: 8K1 955 119 B HW: 8K1 955 119 B Labels: 1KX-955-119.CLB
Component: MITSUBA250613 H18 0461
Serial number: 13061707015550
Coding: 004577

Subsystem 2 - Part No SW: 8U0 955 559 B HW: 8U0 955 559 B Labels: 8U0-955-559.CLB
Component: G397_RLFS H06 0002
Serial number: 21515126
Coding: 02005D

Subsystem 3 - Part No SW: 8K0 941 531 AS HW: 8K0 941 531 AS
Component: E1 - LDS H03 0031
Serial number: 00000000000507130605

Subsystem 4 - Part No SW: 4G0 907 410 A HW: 4H0 907 410 A
Component: USHL4.2 H30 0030
Serial number: 0000002274555R6QTA02

Subsystem 5 - Part No SW: 4H0 907 658 HW: 4H0 907 658
Component: AQ_Hum_Sensor H03 0003
Serial number: A0188AB6000000000001

No fault code found.

-------------------------------------------------------------------------------
Address 15: Airbags (J234) Labels:| 8K0-959-655.clb
Part No SW: 8K0 959 655 P HW: 8K0 959 655 P
Component: AirbagVW-AU10 H47 0610
Serial number: 003KJDB06ZCX Dataset Number: 8K0909602VA 0001
Coding: 303844354730303030304A55304C384B3053
Shop #: WSC 42239 001 1048576
ASAM Dataset: EV_AirbaECUVWAUDI010 003010
ROD: EV_AirbaECUVWAUDI010_003_AU48.rod
VCID: 4ACD62354C3CF78AC97-801E

Seat occupied recognition:
Subsystem 1 - Part No SW: 8K0 959 339 C HW: 8K0 959 339 C
Component: BF-Gewichtss. H02 0040
Serial number: 5810000R130000EKYC

Crash sensor for side airbag: driver side:
Serial number: 6334MSME7C132D43I

Front Passenger's Side Airbag Crash Sensor:
Serial number: 6344MSME7C02327BI

Rear Side Airbag Crash Sensor (on driver's side):
Serial number: 6352QSME73340D62F

Passenger side rear thorax airbag crash sensor:
Serial number: 6362QSME6F343A74U

Crash sensor for front airbag: driver side:
Serial number: 63732SME7D324F5EJ

Crash sensor for front airbag: front passenger side:
Serial number: 63832SME00334178Q

No fault code found.

-------------------------------------------------------------------------------
Address 16: Steering wheel (J527) Labels:. 8K0-953-568.clb
Part No SW: 8K0 953 568 Q HW: 8K0 953 568 Q
Component: Lenks.Modul H03 0003
Revision: C0062331 Serial number: 90862MGA00185
Coding: 000016
Shop #: WSC 02391 785 00200
VCID: 48C9583D52B0059ADF3-801C

Component: E221 - MFL H03 0004

No fault code found.

-------------------------------------------------------------------------------
Address 17: Instruments (J285) Labels:. 8T0-920-xxx-17.clb
Part No SW: 8K0 920 983 F HW: 8K0 920 983 F
Component: KOMBIINSTR. H35 0563
Revision: 00500000 Serial number: WWC505A7E
Coding: 8BB609000301D705020000
Shop #: WSC 02391 785 00200
VCID: 382928FD2250751AAF3-806C

2 Faults Found
00771 - Fuel Level Sensor (G)
010 - Open or Short to Plus - Intermittent
Freeze Frame:
Fault Status: 00101010
Fault Priority: 7
Fault Frequency: 1
Reset counter: 147
Mileage: 291842 km
Time Indication: 0
Date: 2025.02.28
Time: 18:20:05

00438 - Fuel Supply Sensor 2 (G169)
010 - Open or Short to Plus - Intermittent
Freeze Frame:
Fault Status: 00101010
Fault Priority: 7
Fault Frequency: 1
Reset counter: 147
Mileage: 291842 km
Time Indication: 0
Date: 2025.02.28
Time: 18:20:05


-------------------------------------------------------------------------------
Address 19: CAN Gateway (J533) Labels: Redir Fail!
Part No SW: 8R0 907 468 N HW: 8R0 907 468 C
Component: GW-BEM 4CAN-M H11 0056
Revision: 1Y070028 Serial number: 2841Y137030131
Coding: 80C303FF00
Shop #: WSC 02391 785 00200
VCID: 4ACD62354CBCF78AC97-801E

Subsystem 1 - Part No SW: 8T0 915 181 HW: 8T0 915 181
Component: J367-BDMHella H03 8041
Serial number: 4169700903

1 Fault Found
01333 - Door Control Module; Rear Left (J388)
004 - No Signal/Communication - Intermittent
Freeze Frame:
Fault Status: 00100100
Fault Priority: 2
Fault Frequency: 22
Reset counter: 147
Mileage: 291139 km
Time Indication: 0
Date: 2025.02.22
Time: 11:27:12

Freeze Frame:
Bin. Bits: 01111
Voltage: 14.30 V
Count: 6
Bin. Bits: 00000
Time: 25.40 s


-------------------------------------------------------------------------------
Address 36: Seat Mem. Drvr (J136) Labels:. 8T0-959-760.clb
Part No SW: 8K0 959 760 D HW: 8K0 959 760 D
Component: MEM-FS H06 0076
Revision: AA000000 Serial number: 00000066099528
Coding: 00581B00000000000000
Shop #: WSC 02391 785 00200
VCID: 3B2337F113665E02421-806E

No fault code found.

-------------------------------------------------------------------------------
Address 42: Door Elect, Driver (J386) Labels:. 8K0-959-793.clb
Part No SW: 8T0 959 793 P HW: 8T0 959 793 G
Component: TSG FA H09 0305
Revision: -------- Serial number: --------------
Coding: 011C13204E00410001
Shop #: WSC 02391 785 00200
VCID: 56F586458804A36A5DF-8002

1 Fault Found
01333 - Door Control Module; Rear Left (J388)
004 - No Signal/Communication - Intermittent
Freeze Frame:
Fault Status: 00100100
Fault Priority: 6
Fault Frequency: 5
Reset counter: 147
Mileage: 291842 km
Time Indication: 0
Date: 2025.02.28
Time: 18:07:26


-------------------------------------------------------------------------------
Address 44: Steering Assist (J500) Labels:* None
Part No SW: 8K0 909 144 F HW: 8K0 909 144 B
Component: RCEPS H37 0507
Revision: 00001000 Serial number: 0010662140 Dataset Number: 8K0909852H 0023
Coding: 100000000001
Shop #: WSC 02391 785 00200
ASAM Dataset: EV_RCEPSAU48X 008014
ROD: EV_RCEPSAU48X_008.rod
VCID: 34311CCD3EB8917A83B-8060

No fault code found.

-------------------------------------------------------------------------------
Address 46: Central Conv. (J393) Labels:. 8K0-907-064-46.clb
Part No SW: 8K0 907 064 GM HW: 8K0 907 064 FM
Component: BCM2 2.0 H12 0633
Revision: 00002001 Serial number: 0311562430
Coding: 0106023A00FA400580B0013200000000
Shop #: WSC 02391 785 00200
VCID: 015F8519310AF4D258D-8054

Subsystem 1 - Part No SW: 8K0 959 719 B HW: 8K0 959 719
Component: GTO BF H01 0080
Serial number: 00000000000000700897

Subsystem 2 - Part No: 1K0 951 605 C
Component: LIN BACKUP HO H05 1501

Subsystem 3 - Part No SW: 8K0 959 591 B HW: 8K0 959 591
Component: J245 PS050 H08 0043

3 Faults Found
02616 - Fuel Tank Cap; Unlock
009 - Open or Short to Ground - Intermittent
Freeze Frame:
Fault Status: 00101001
Fault Priority: 2
Fault Frequency: 2
Reset counter: 147
Mileage: 291842 km
Time Indication: 0
Date: 2025.02.28
Time: 18:04:07

02615 - Fuel Tank Cap; Lock
009 - Open or Short to Ground
Freeze Frame:
Fault Status: 01101001
Fault Priority: 2
Fault Frequency: 1
Reset counter: 107
Mileage: 291842 km
Time Indication: 0
Date: 2025.02.28
Time: 18:05:05

01333 - Door Control Module; Rear Left (J388)
004 - No Signal/Communication - Intermittent
Freeze Frame:
Fault Status: 00100100
Fault Priority: 6
Fault Frequency: 12
Reset counter: 147
Mileage: 291842 km
Time Indication: 0
Date: 2025.02.28
Time: 18:07:04


-------------------------------------------------------------------------------
Address 47: Sound System (J525) Labels: Redir Fail!
Part No SW: 8T1 035 223 A HW: 8T1 035 223 A
Component: DSP Prem H05 0030
Revision: 00005001 Serial number: 94813017055703
VCID: 2D0709A9DD12C0B2CC5-8078

No fault code found.

-------------------------------------------------------------------------------
Address 52: Door Elect, Pass. (J387) Labels:. 8K0-959-792.clb
Part No SW: 8T0 959 792 P HW: 8T0 959 792 G
Component: TSG BF H09 0305
Revision: -------- Serial number: --------------
Coding: 011C13204E00410001
Shop #: WSC 02391 785 00200
VCID: 55F781499502A872545-8000

No fault code found.

-------------------------------------------------------------------------------
Address 53: Parking Brake (----) Labels: 8K0-907-801-V2.clb
Part No SW: 8K0 907 801 M HW: 8K0 907 801 J
Component: EPB-4 H01 0004
Revision: -------- Serial number: 20000000306351
ASAM Dataset: EV_ParkiBrake 001028
ROD: EV_ParkiBrake_AU48.rod
VCID: 392F2DF919DA6C1250D-806C

No fault code found.

-------------------------------------------------------------------------------
Address 56: Radio (R) Labels:. 4F0-035-0xx-56.clb
Part No SW: 4G0 035 082 G HW: 4G0 035 082
Component: Radio U SIRIU H60 0133
Revision: AB001007 Serial number: 156G10D7828056
Coding: 020007010000000001
Shop #: WSC 02391 785 00200
VCID: 2411EC8D8ED801FA13B-8070

No fault code found.

-------------------------------------------------------------------------------
Address 5F: Information Electr. (J794) Labels:. 4E0-035-6xx-5F.clb
Part No SW: 8R1 035 746 D HW: 8R1 035 746 D
Component: H-BNT-NA H40 0738
Revision: -------- Serial number: 204G50D7589926
Coding: 0F0200000006A1EF41028B4E00000403140000000000000000
Shop #: WSC 02391 785 00200
VCID: 382928FD2250751AAF3-806C

Subsystem 1 - Part No: 8R0 060 884 BD
Component: NAR 2013/2014 0802

Subsystem 2 - Part No SW: 8R0 919 604 A HW: 8R0 919 604 A
Component: DU7 High H42 0104
Serial number: A130G+0D2779376

Subsystem 3 - Part No SW: 8T0 919 611 L HW: 8T0 919 611 C
Component: E0380 Bedient H02 0030
Serial number: 00000001561275

Subsystem 4 - Part No: 8R0 060 961 F
Component: CD-Database 5298

No fault code found.

-------------------------------------------------------------------------------
Address 62: Door, Rear Left (J388) Labels:. 8K0-959-795.clb
Part No SW: 8T0 959 795 Q HW: 8T0 959 795 H
Component: TSG HL H07 0305
Revision: -------- Serial number: --------------
Coding: 010C13204000210001
Shop #: WSC 02391 785 00200
VCID: 59EF8D79F91A8C1270D-800C

2 Faults Found
02115 - Locking Unit for Central Locking
008 - Implausible Signal - Intermittent
Freeze Frame:
Fault Status: 00101000
Fault Priority: 3
Fault Frequency: 3
Reset counter: 107
Mileage: 291842 km
Time Indication: 0
Date: 2025.02.27
Time: 20:03:31

00532 - Supply Voltage B+
002 - Lower Limit Exceeded - Intermittent
Freeze Frame:
Fault Status: 00100010
Fault Priority: 2
Fault Frequency: 3
Reset counter: 40
Time Indication: 0
Date: 2025.02.28
Time: 18:10:00


-------------------------------------------------------------------------------
Address 6C: Back-up Cam. Labels: None
Part No SW: 8T0 907 441 C HW: 4L0 907 441 B
Component: J772__Rearview 0040
Revision: --H08--- Serial number: 525PA8-J3690VR
Coding: 1000006
Shop #: WSC 02391 785 00200
VCID: 382928FD2E50751AAF3-806C

No fault code found.

-------------------------------------------------------------------------------
Address 72: Door, Rear Right (J389) Labels:. 8K0-959-794.clb
Part No SW: 8T0 959 795 Q HW: 8T0 959 795 H
Component: TSG HR H07 0305
Revision: -------- Serial number: --------------
Coding: 010C13204000210001
Shop #: WSC 02391 785 00200
VCID: 59EF8D79F91A8C1270D-800C

No fault code found.

[Zackattack]

IMG_2017.jpg

I found and repaired the issue with the rear left door. Now troubleshooting the fuel pump control module.

I tried to run a test thru vcds but it says "refused by control module" 7F 2F 00 whatever that means. I'm using the troubleshooting guide on alldata. The only fault code i'm getting now is P025A (14627 in VCDS) fuel pump control module electrical fault. I bought another module off ebay and I get the same fault. The guy says he "tested" it by driving the car around but I think he just owns a junk yard and is full of bs. What's the odds the one I get is no good either?

[Smac770]

This is a B8.5, meaning the 3-phase pump. You should lift the pump out and check the terminal pins at the flange connector to see if any have burned out. Not unheard of for the B8.5.

You also have fuel level sensor codes, or are those from playing around with the connectors at the fuel pump? The level sensors are on a different connector plug than the pump.

Voltage terminal 30: 11.591 V
That's never a good thing.

There's not much you can do with testing the pump controller, but you need to try and isolate is it actually the controller, or the pump itself.

4-pin on the pump, pin 4 is ground and pins 1-3 are the three motor phases. The ground line is not a large wire since it shouldn't be carrying current normally.
6-pin on the J538 (pump controller), pins 1-3 are the three motor phases, 4 is ground (pump and J538 ground lines splice together), 5 is 12v from the fuse, 6 is the PWM signal from the ECM

Does 5>4 measure "12v" when ignition on?
6>4 should measure "up to 12v" when the ECM is trying to run the pump. You'd need to confirm the fuel pump duty cycle in the measuring values to know what you should be expecting on 6.

[Zackattack]

All of the other codes related to the fuel system were from unplugging the harnesses. I only have the P025A remaining.

For some reason I can't attach the test plan from alldata that I've done. So I'll try to explain it.

- When the ignition is on I can hear the pump prime - verified
- At J538 (control module) harness terminals 5(white/black) to 4(brown) I have 12.5V with a charger hooked up to the battery
- Terminal 4 (brown) to battery + is 13.6 (charger attached)
- Plug J538 module back in and unplug GX1 (fuel pump) harness, check terminals 3(white) to 4(brown) for voltage while cranking. Look for 7-11V, I do not get this I get .5VDC and 1VAC (not sure if its AC or DC I'm looking for doesn't say)
- ring out all module to pump wires (Yellow, Red, White & Brown) all 0 ohms
- GX1 harness ground (pin 4) to chassis ground at 0 ohms
- Check J538 harness pin 6 (red/violet) to ECU T94 pin 76 - 0 Ohms

Basically it says if all this occurs replace the fuel pump control module J538.

However....The red/violet pin 6 on the J538 to ECU pin 76 wire. This is obviously some control signal coming from the ECU to tell the module how much power to give the pump. I'm not sure what that signal is supposed to be or what the input is for that output. So what input to the ECU makes the output go up or down?

The Pin 6 wire for J538 at back probe during cranking flashes open for a second and then comes back with 6V. At prime (KOEO) its 5.5-6 and then if I continue to crank its staying around 6V. Again not sure if this is good or bad?

I'm about to just buy a new control unit for sanity.

Zach

[Zackattack]

Maybe this is the issue. I thought any 4G0906093J module would do but looking at ECS tuning some of the same model numbers say they do not fit? Could that be the issue? The one I got from ebay was for a 2016 A6. Has the same part number on it, I figured a part number is a part number. Now I'm thinking there's specific firmware.

[Smac770]

The original pump controller for the US B8.5 was 4G0 906 093 G, later replaced by 4G0 906 093 J. There's no color codes or other differentiators beyond the basic part number for that unit. So any 4G0 906 093 J is the same as any other 4G0 906 093 J.

G/J is for US spec vehicles (A8U). F/H is for not-US spec vehicles (A8S). Why are there different units; what's actually different? No idea.

So it's not a wrong controller p/n issue.


Back up to your measurements. Presuming red and black probes on the multimeter,
red on harness connector pin 5, black on harness connector pin 4, you got 12.5V
red on battery +, black on harness connector pin 4, you got 13.6V
that's a large loss somewhere
what did you get for red on harness connector pin 5, black on battery - ?
and what's the baseline voltage, red on battery +. black on battery - ?

(I have the Audi workshop manual Generic Scan Tool for CPM, so I can see the process it's stepping you through)


I already mentioned "6 is the PWM signal from the ECM". So PWM, pulse width modulation. Not sure what the base frequency is for the three-phase pump in the B8.5. Only doc I find that specs a frequency is 20 Hz, but that's an old doc.

P025A, Fuel Pump - Open circuit, Signal voltage > 5.05 ± 0.35 V
P025C, Fuel Pump - Short to ground, Signal voltage < 3.0 ± 0.26 V

So when you measure a PWM signal with a meter, you get basically an averaged value. Say I want to run a 12v bulb at 50% output. I could send it 6V. Or I could send it 12v, 50% of the time. A computer system would see flickering at whatever the PWM signal frequency was, but a human just sees 50% averaged. This is the flicker thing with old florescents on 60 Hz AC. The pump is a physical object with momentum. And the electric pump in it runs most efficiently at 100% powered. So instead of running it at some reduced power level, you run it at a reduced duty cycle.

For a 12.5V power level, 6V would be just under 50%.

The CPM engine has a low pressure line pressure sensor. So the ECM knows if it needs to drive the fuel pump more or less to deliver the pressure level expected. There should be a specified spec in the measuring values as well. Probably 6 bar (600 kPa).


Did you check any of the other phases on the pump? 3 to 4, but what about 1 to 4 and 2 to 4? Could be the issue is with pin 3.

The signal from the controller to the pump phases will be PWM as well. That'll look like AC, particularly near 50% duty cycle. DC will give you an averaged value. Yeah, that 7-11V is not well qualified.


Unfortunately, I don't own a B8.5, so I can't do any counter testing on a known good for you.

[Zackattack]

Back at it. The voltage drop from Brown pin 4 to batt + vs brown to white/black pin 5 had me thinking.

I traced Pin 6 red/violet back to the ECU at 0ohms. Check it to ground and was open. So all good on that wire.

Now to pin 5 white/black. Checked to ground and have about 350K. (all wire continuity is done w battery - disconnected).

Traced this wire back to SC3 (drivers fuse panel 3) pulled the fuse and measured from module to fuse panel for ground and circuit was open.
Traced the incoming side of the fuse panel to ground and have 350K.
Pulled both connectors and pulled ECU
Traced the wire thru plug T17q pin16 (red plug inside ECU fuse panel B) disconnected it and again open circuit for ground.
Traced wire from male pin 16 back to J271 motronic engine control module power supply relay pin 5. Removed relay and pin 5 to ground is 8K. Removed J575 ECU relay and still 8K. There are a lot of sensors tied into the tree for that branch and I'm certain this is where the resistance to ground is coming. I think this is normal.
After plugging everything back in I'm at 1K from the white/blk pin 3 to brown pin 4 on the fuel pump controller harness.
B+ to B- (at the battery) 12.4V
White/black pin 5 to pin 4 brown 12.33V KOEO
Hooked up my fuel pressure gauge. Absolutely 0 pressure.

Checked the red/viotet PWM signal pin 6 from the ecu and getting 105-110Hz AC at prime, thats at 1VAC.

Checked all 3 phases output from controller all are 1VAC @18Hz; .5VDC

Back probed white/black pin 5 to pin 4 ground on fuel pump controller and still got batt V while under load.

So I ordered a new controller. At this point what else can I troubleshoot. The wiring system seems fine, the ECU seems to be giving "A" signal to the inverter. No idea what that signal is supposed to be. The only thing left is the controller or the ECU. It can't be anything else.

[Zackattack]

Was there any coding I was supposed to do for the module or is it plug and play?

[Smac770]

There's nothing to code or adapt; the p/n sets the software load and that sets everything for the application.

The pump controller 12v on pin 5 comes through fuse 3 in column brown on the driver's end of the dash. The 12v to this fuse comes from the J271 relay in the ECM box. This relay powers pretty much everything related to engine operation. This relay is powered directly from the battery (the threaded post with the large red wire in the ECM box is the junction point of the feed line from the battery).

You can't use resistance measurement really on the supply side of that pump fuse. There's far too many connection points. What matters is the voltage level. I'd check the voltage from that threaded post to the negative jump start post. It should measure the same as from the battery + to the battery -. But 12.0v-15.0v is enough for the J538 to operate correctly, so long as the voltage isn't sagging under operation (it will a bit while cranking, but that's not our focus).

If you're only getting 1 Vac from the ECM, that the controller is passing that along as 1 Vac to the pump doesn't seem too odd. Based on the P codes, I'd think normal operation would see 3 to 5 Vdc on the PWM signal pin. I was going to try some measurements, but the J538 is buried and can't pull it out with the pump installed.

So the leading "that doesn't look good" is actually the PWM signal from the ECM. Unfortunately, multimeters are not great tools for a voltage waveform; one really needs a proper scope tool for such things. But in this instance, a DC voltage reading should be sufficient to convey there is or isn't the expected signal. And it seems like the signal from the ECM is not as expected.

The signal frequency to the motor is 20 Hz; that looks good. But looking around, it appears the PWM from the ECM is actually a 20 kHz signal. That you're getting 100 Hz, might be a limit of the meter. But a Vdc measurement, relative to "12v" as 100%, would be reliable enough to convey the PWM duty cycle. What duty cycle is shown in the fuel pump measuring value? Multiple that by the current B+ voltage (higher when engine running, etc) and that should be the Vdc measurement on pin 6.

[Zackattack]

I cant get to that measuring value because I cannot communicate with the module thru VCDS. It just will not allow me to do anything.

[Smac770]

Not the J538, look at the measuring values of the J623 ECM, 01-engine. It's giving the order to the J538; it knows what it is commanding. And the signal measured should resemble the command.

IDE00202 Low fuel pressure: specified value	600.0 kPa
IDE00186 Fuel low pressure: actual value	601.9 kPa
IDE01893 Fuel pump: specified value		26.057 %

So we see low pressure line target, low pressure line measured, and the duty cycle of the in-tank pump which drives the low pressure line. Those are from a blockmap of an idling CPMB that someone had posted. It was idling at 815 rpm with system voltage at 14.5 V. So I'd expect a Vdc measurement of the signal on pin 6 to be maybe around 3.6 V.

I take it was running on normal gasoline:

IDE00555 Alcohol content in fuel	10 %
IDE04818 Ethanol content in fuel	10.2 %

If you're using the output test to command the ECM to invoke the in-tank pump, I believe that's always at 100% (or max) duty cycle? Cranking, don't know what you might see; wouldn't surprise me if the engine was saying "go all out" until the engine is fired. The line can't overpressure; the relief valve in the flange opens at just over 8 bar (800 kPa), iirc.

[Zackattack]

Attached are the measuring values.

The picture with the higher fuel pump % is during the prime cycle KOEO. The 10% is after the prime cycle no cranking.

I use E85 as this is a flex fuel engine. Have used E85 for the past 3 years only premium when doing a mpg test on the two fuels for efficiency reasons.

[Smac770]

The 10% is probably a minimal reported value, like the 10% for the fan activation.

When cranking, we see 62%, so we'd expect the PWM signal to measure something like 7.x Vdc on a meter. And we see the low line pressure is not building at all, not even 100 kPa. It's still curious that the P code is for >5.0 Vdc.

If you go back to the red/violet wire. Disconnect it from both ends (J623 ECM and J538 pump controller). You said it measured "0" ohms end to end. But also do a voltage measurement between it and the battery (or jump start post) + and -. Does it have any reading to either B+ or chassis? If the wire is good, must be one of the electronic units on either end. Hopefully the alternative J538 will fix it up. Having to replace the J623 is a not cheap consideration.


Heh, youtu.be/LwxjO9plAQ4?t=638 particular point in a video from this thread (where the eventual solve was a replacement J538), https://www.audizine.com/forum/showt...-getting-power

And that seems to emulate the P codes, where the Vdc on the signal line seems to be a very small range (3-5V for the CPM). For the Gen3 CYMC, that range is only 2-3V. It seems to be much more a current source scenario rather than voltage source scenario. Very hard to really assess with a meter, in that case.

youtu.be/kGsLW7_4h68 A better video showing using a scope to assess 3-phase pump. But it also shows that an ammeter is an almost necessary tool for accessing the 3-phase AC side of the pump controller.


The thing I've wondered as well is if a problem in the pump can feed back through the J538 circuit design to cause a input signal issue. So could it be the pump itself. 8K0919051AN, holy hell, those things got expensive. Maybe lift one from a junker as an A/B test, if an alternative J538 doesn't sort it.

The J538 dying isn't unheard of, but usually it's from heat, so that it's in the winter is different. The pump developing electrical issues at the connector pins is not unheard of, for that 3-phase pump. And people have had ECM failures, but don't think I recall anyone posting of one for the fuel pump duty cycle signal.

[Zackattack]

The red/violet wire was open to ground. However as you mentioned a multimeter isn't going to find insulation deficiencies. I have a megger but I'm not going to use that because the odds of an insulation issue on a low current signal wire is low. I can get an oscilloscope but in all honesty the module comes tomorrow. If that doesn't work I have a bead on a used ECM for $70. This is all low cost compared to the value of my time. I've currently wasted about 10 hrs troubleshooting the entire circuit in the vehicle. The ECM didn't seem to have any sign of water ingress, there were no damaged wires or anything and all the pins looked good. I can't imagine the only output that dies on the ecm is the pump activation but I've seen crazier things. I always say, if it's possible then it will happen to me!

[Smac770]

And it being the pump or the pump controller would be much more in line with what's come up in the threads here over the years. Than it being that wire or the ECM. The pump controller seemed to be common in early B8, particularly in connection with hot environments. For the B8.5, the most common thing that I recall being posted was the connector pins in the pump flange itself burning out. Bad crimp/solder job I presume.

[Zackattack]

Ok new J538 didn't work, but we already knew it wasn't going to.

Measured the control wire red/violet again during prime & crank and now it's 2.2VDC about 1.7VAC both when priming and cranking. The signal coming in is too low and seems to be all over the map. When I first started I was getting open for a few seconds and then jumping to 6+VDC. Then two days ago I was getting .5VDC and now today I'm getting 2.2VDC. I did a system scan, cleared all DTCs and then rescanned. The rescan says all systems are ok. Even when I go into the engine module there's no DTC but yet the EPC light is still on the dash. It doesn't go away even when I clear DTC or take the negative off the battery.

So here's some interesting info:

I took red/violet wire and measured it to the white/black B+ wire in the harness and then hit the ignition (KOEO) and got 10.5VDC during the prime cycle and battery voltage after. The battery voltage stayed for 30 seconds after ignition shut off.

The 2+ VDC I'm measuring from that wire to ground during the prime cycle is being subtracted when I measure the red/violet wire to B+. I'm assuming there's a short inside the ECM? ECM is my next move here I'm going to return the J538.

Even more interesting if I leave the meter hooked up once it drops out of battery voltage (this is with ignition off btw) if I open or close any door it jumps back to battery voltage. If I measure white/black to brown ground wires it does the same. Need to check the schematic but looks like the red/violet is def offering a ground path.

Edit: The ground path is coming from the PWM AC signal. Believe this to be normal. Ordered ECM. Will try that.

[Zackattack]

Well....

Removed the ECU and left the connectors on. Left the fuel pump controller plugged in and the GX1 connector attached to the pump. Back probed the red/violet there. 6.8VDC and 5.6VAC. Went to the fuel pump and back probed all 3 phases to ground. Getting 3.8VAC & 3.6VDC from all 3 phases. I'm not sure what the actual voltage is supposed to be at the pump! I can't find it anywhere.

When I measured the outputs previously it was with the module and fuel pump unplugged. I was getting 2V on the signal and about 1V on the pump side when plugging in the module. With everything plugged in and back probing I'm getting much better values. Something tells me 3.8V should be able to generate fuel moving out of this pump but there's physically no fuel coming out. I can hear the pump spinning however.

So my options are:

Used fuel pump for $60 (says its tested) and try that
Send my ECU for repair $125 if its NTF and $228 if it needs repaired.

Which way to go?

[Smac770]

I'd try the pump before I'd try the ECM. It's simply more likely to have gone out, imo. Then again, maybe you got the short straw this time.

[Zackattack]

Smac770 - thank you for all the support you're a great troubleshooter indeed. However, I am an idiot.

I removed the pump 2x to check wiring connections and only realized when I was looking for a replacement pump that the filter was on the output side not on the suction side and therefore the way the filter was on my pump was not normal. It had popped off the flange and was at the bottom of the tank still attached by the hose. No wonder I wasn't getting any pressure. I re-attached it and the car runs now.

On another note I did measure the phases at idle and at prime.

Red/violet - Runs about 4.5VAC at prime, 3.5VAC at idle
All 3 phases run about 3.8VAC at prime and 2.2VAC at idle.

Using these numbers with the pump duty cycle we can infer:
No more that 6VAC on the red/violet and no less than 3VAC
No more than 4.5VAC on each phase and no less than 2.2VAC

It doesn't take much AC to run this pump. The alldata troubleshooting guide was incorrect when it asked to look for 7-11v from phase to ground. Basically the VDC and VAC numbers are very close because pwm is a pulsed DC signal but can be read more efficiently as AC. You're never going to get 7-11VAC out of this controller.

[Smac770]

Doh! So do you feel the original issue was the filter falling out of place for whatever reason? Or it got knocked out of place by all the movement, and the original issue was a toast J538?

I suspect the 7-11V was copied over from the B8.0 era, with the single phase pump. Would not be the first time, at all, that the documentation was guilty of errant copy/pasting.

Thanks for the updating of first hand measurements of a known good. Yeah, the more I looked, the more it looked like the voltage range really is very small for the three-phase, and so the P code trigger values now do make sense.

[Zackattack]

I’ve been driving it, seems to be fine. That filter is clipped in there really good I can’t imagine how it fell out? Only thing I can think is we had a really bad winter and the roads were very rough for a while. That plus my subwoofer may have had a hand in it? Still seems crazy to me.