View Full Version : 2001 audi a4 2.8l 30v - voltage drops/power loss

07-15-2012, 05:32 PM
Hey everyone,
Im going to give a descriptive account of events so the experts know the circumstances.

I bought this audi a few weeks ago. It came with a bad alternator but was about to drive it home, only have to jump once over 85 miles. A few days later, a mechanic friend and i take out the alternator and take it to the auto parts store to test, I was told it doesn't even test to 90 amps and their was coolant corrosion which is indicated it failed from a coolant short. So i then bought a brand new alternator and pop it in. Put the front end back together properly and fire up the car. Everything looked good and the voltage meter held at a steady 13.8 to 14. Three days later i notice a leak, it is from a short hose right next to the alternator. It had a burst with a half inch flap. It was not a vigorous drip so i put gorilla tape around it and zip tied it. (I know not the best but i couldnt fix it that day) Just 3 days later I replace the hose and there is no leak. DURING THE PAST 6 DAYS of dealing with the hose, the voltage was great and holding. So on the 6th day I fix the hose, I start to have voltage drops on my gauge. It ranges from 10 to 13v. 12v average when in gear and driving, but dips to 10 often. BUT, when in park it has a steady 13 (decent). My voltage gauge also dips when i roll down the windows, use the brake, use the gas (accelerate) or use the blinkers (which throbs to the pulse of the blink) or pretty much anything electric. So i wait 3 days and run another diagnostic and clear the computer. After that the voltage RETURNED TO 14v and held for about 10 miles. Then i start to see it dip slowly down to an average of 11-12v. (then back to the drops when using electrics) It has been like that for the past week, my mechanic friend and I are running out of ideas and would like an experts opinion. I have tried swapping the battery with my other car and it does the same. Because the battery already had a nice charge it was good for the day. But the day after it started doing the same thing, so i switched them back. Please list any ideas you have, I have tried a bunch already, too many to remember or list. Knowing i have a good alternator and battery.

Diagnostic scan from when i bought the car:
Chassis Type: 8D - Audi A4 B5
Scan: 01 02 03 08 15 16 17 25 35 37 45 55 56 57 67 75 76 77

Address 01: Engine Labels: 078-907-551-ATQ.lbl
Part No: 3B0 907 551 BQ
Component: 2.8L V6/5V G 0001
Coding: 07551
Shop #: WSC 63351
VCID: 73E564F941AE091

4 Faults Found:
18032 - MIL Request Signal Active (Check TCM for errors too!)
P1624 - 35-00 -
17977 - Cruise Control Switch (E45)
P1569 - 35-10 - Implausible Signal - Intermittent
18010 - Power Supply Terminal 30
P1602 - 35-00 - Voltage too Low
16947 - System Voltage
P0563 - 35-10 - Too High - Intermittent
Readiness: 0000 1000

Address 02: Auto Trans Labels: 01V-927-156.lbl
Part No: 8D0 927 156 AS
Component: AG5 01V 2.8l5V USA 3132
Coding: 00004
Shop #: WSC 63351

2 Faults Found:
17125 - Torque Converter Clutch
P0741 - 35-00 - Stuck OFF / No Power being transferred
18159 - Supply Voltage
P1751 - 35-10 - too High - Intermittent

Address 03: ABS Brakes Labels: 8E0-614-111-ASR.lbl
Part No: 3B0 614 111
Component: ABS/ASR 5.3 FRONT D00
Coding: 00031
Shop #: WSC 06435
VCID: D3A5447921EEE91

No fault code found.

Address 08: Auto HVAC Labels: 8D0-820-043-1D.lbl
Part No: 8D0 820 043 Q
Component: A4 KLIMAAUTOMAT D58
Coding: 00160
Shop #: WSC 63351
VCID: 2E53B58DEA0C649

No fault code found.

Address 15: Airbags Labels: 8D0-959-655-AI8.lbl
Part No: 8D0 959 655 G
Component: Airbag Front+Kopf 1002
Coding: 00304
Shop #: WSC 63351
VCID: 3A7B89DD2644B89

1 Fault Found:
00532 - Supply Voltage B+
07-10 - Signal too Low - Intermittent

Address 17: Instruments Labels: 8D0-920-xxx-17.lbl
Part No: 8D0 920 980 DX
Component: B5-KOMBIINSTR. VDO D13
Coding: 02262
Shop #: WSC 54321
VCID: 8407B7259400BE9

No fault code found.

Address 35: Centr. Locks Labels: 8D0-862-257.lbl
Part No: 8L0 862 257 N
Component: CV-Pump, Alarm, RC D16
Coding: 16140
Shop #: WSC 63351
VCID: 408FFB354098E29

3 Faults Found:
01367 - Central Locking Pump Run Time Exceeded (Likely Leak)
35-00 - -
01370 - Alarm triggered by Interior Monitoring
35-00 - -
00955 - Key 1
09-00 - Adaptation Limit Surpassed

Address 45: Inter. Monitor Labels: 4B0-951-173.lbl
Part No: 4B0 951 173
Component: Innenraumueberw. D03
Coding: 00101
Shop #: WSC 63351
VCID: E0CF9BB56058029

2 Faults Found:
01382 - Alarm triggered by Anti-Theft Sensor; Front Left
35-00 - -
01383 - Alarm triggered by Anti-Theft Sensor; Front Right
35-00 - -

End ---------------------------------------------------------------------

07-17-2012, 08:06 AM
try to disconnect the battery when the car is running and note what happens. Its not impossible for new parts to be defective so maybe your new alternator could be defective or it may have shorted again from getting some coolant on it. I would say fix the coolant leak first before you replace the alternator again. IF you remove your battery and the car shuts off its clear cut your alternator is bad.