Cruise Control Diagnosis

[alphaVR]

I recently was having issues with my upper limit clutch sensor in that I was getting random CELs for an improbable sensor position. No big deal, I'll order a replacement. OEM Part# on the stock sensor was 8D0911807A and bought a direct replacement from Europaparts. The replacement I got was a bit shorter in overall length but plugs in just fine and far as I can tell works perfectly - when I push the clutch pedal in, the rev rate slows as it normally should. As well, I am no longer getting any intermittent codes or a CEL for the clutch pedal sensor, which is great.

The problem now is the Cruise Control - I can't get it to enable anymore. Now, a few years ago I was having some intermittent issues with Cruise where the buttons on the stalk wouldn't work but after a couple weeks it's been fine for the last couple years until I switched out this sensor the other week. With all that being said, where do I go from here? I am considering putting the old clutch pedal sensor in just to see if that somehow makes a difference, but I am skeptical. My thought is it's the stalk itself but I haven't the slightest clue how to diagnose it. Looking for any and all input on how to get this figured out - I have a 1600 mile road trip coming up in a few weeks and I am not looking forward to not having cruise control available for it.

[Zba]

I haven't been under the dash in a while, but there should be two clutch switches, one on the upper limit and one for the lower limit. If your upper limit switch isn't adjusted properly, the ECU will think you are depressing the clutch which interrupts cruise operation.

Alternatively, you should be able to check the switch positions (clutch and stalk) with VAGCOM.

The fact it started acting up after replacing a clutch switch should give you a clue as to where to look first.

[jbain2]

It’s still possible they are unrelated. I would take some electronic spray cleaner and blast the cruise switch. Hold a Tupperware or something underneath to catch the dripping.




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[alphaVR]

I haven't been under the dash in a while, but there should be two clutch switches, one on the upper limit and one for the lower limit. If your upper limit switch isn't adjusted properly, the ECU will think you are depressing the clutch which interrupts cruise operation.

Alternatively, you should be able to check the switch positions (clutch and stalk) with VAGCOM.

The fact it started acting up after replacing a clutch switch should give you a clue as to where to look first.

Same thoughts I had re: cause/effect. Just didn't add up right away since the RPMs are "held" by the ECU like you'd normally expect when the clutch is depressed. And, as I mentioned, the intermittent CEL for the clutch position went away.

Any idea where the upper limit sensor (the one in question) should be adjusted to? When I installed the new sensor, I let the clutch pedal sit where it normally would and adjusted the sensor until the plunger was fully depressed against the clutch pedal. Should it be adjusted down further?

I'll have to dig into VCDS outputs to see where I can monitor those switches.

[alphaVR]

Found this. I am assuming this is what you were referring to re: checking switch positions:

http://wiki.ross-tech.com/wiki/index...asuring_Values

[christianb5s4]

Another thing I've seen happen besides the clutch position switches are the cruise control stalk itself going bad, likely not your issue but if the switches don't do the trick that could be another place to look.

[CJ_]

Found this. I am assuming this is what you were referring to re: checking switch positions:

http://wiki.ross-tech.com/wiki/index...asuring_Values

That’s the guide I used for hooking back up cruise control after my 6 spd swap. Just go to block 066, push in clutch and see if one of the values changes from 0-1 or 1-0, can’t remember. If nothing changes it’s the switch, if it does, I’d start looking elsewhere

Another test is to see if you have launch control with clutch pressed in. Let off clutch and see if launch control is still enabled

[Zba]

I forgot to mention make sure your brake switch is operating properly. Just because the brake lights aren't on doesn't mean the switch isn't closed. Check MVB for that as well

Found this


Gasoline engines with electronically-operated throttle valve only
Testing cruise control system
- Connect VAG1551 scan tool and use "Address word 01" to select engine control module. Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks", under "Lighting and Horns"
The engine should be idling.
Except for the control lever, there are no system components for the cruise control system. All functions are carried out by the engine control module.
Initiating "Read Measuring Value Block" scan tool function 08
Indicated on display
Rapid data transfer HELP
Select function XX
- Press -0- and -8- to select "Read Measuring Value Block" function 08.
Indicated on display
Rapid data transfer Q
08-Read measuring value block
- Press -Q- button to confirm input.
Indicated on display
Read measuring value block HELP
Input display group number XXX
- Enter display group number 066.
The engine should be idling.
- Press -Q- button to confirm input.
The measured value block which has been selected will appear in the standard format.
Display group overview
Display group number Display fields
066 1 = Actual vehicle speed km/h
2 = Switch positions of brake, clutch and cruise control (open or closed)
3 = Desired vehicle speed km/h
4 = Control lever switch posit ions
Indicated on display
Read Measuring Value Block 66 ->
0 km/h 1000 0 km/h 0000
Checking displays in display fields 2 and 4
Display check, display field 2
Read Measuring Value Block 66 ->
0 km/h 1000 km/h 0000
Test conditions Display field 2
Cruise control released (activated)1000
Brake applied(break pedal switch)1011
Clutch applied 1100
If the nominal value in display field 2 for "cruise control released" (1000) is not attained:
- Check engine control module identification.
- If "G" is not displayed after component name, cruise control is not activated. Activate cruise control system.
Display check, display field 4
Read Measuring Value Block 66 ->
0 km/h 1000 0 km/h 0000
Test conditions Display field
Switch -B- in "OFF" (AUS) position0000
Switch -B- to "ON" (EIN) position0011
Memory set, switch -B- to "OFF"0001
(AUS) before engaging
Button -A- pressed, "SET" (FIX)0111
Switch -B- to "RES" (AUFN) 1011

[alphaVR]

Thanks for the input. I was able to go do some basic "datalogging" of the two measuring values for the switch positions. Unfortunately wasn't able to do a test drive as its really effing cold, snowing, and the car is sitting on band new Michelin Pilot Sport 4s tires. Aka no bueno in freezing temps

Anyways, here's the outputs for the given scenarios:



Cruise switch off, no pedals pushed
1100 0000

Cruise off, clutch pedal pressed
1000 0000

Cruise off, brake pedal depressed
1111 0000

Cruise ON, no pedals depressed
1100 0011

Cruise ON, clutch pedal depressed
1000 0011

Cruise ON, brake pedal depressed
1111 0011

Cruise ON, cruise set button pressed
1100 0111

Cruise ON, Resume button pulled
1100 1011


Of the above, the only one that doesn't make total sense is the first one. 1100 of the 1st group correlates to "Clutch Applied", so I am assuming this to mean "clutch engaged" or in other words "clutch pedal not depressed", but its not abundantly clear. I did also see an intermittent code for the switch stalk which is a good thing. Cleared that. I am hoping to get a test drive in later this week once the weather warms up a bit to see if things have corrected themselves.

[CJ_]

Just checked mine,

Cruise off, no pedals pressed 1000 0000
Cruise off, clutch pressed 1100 0000
Cruise off brake pressed 1011 0000
Cruise off both pressed 1111 0000

Looks like you got a normally closed clutch switch

I’d be willing to bet your anti lag works with the clutch out and disables with the clutch pressed also

[Robsa6]

Do you have a "G" in the software code when you pull the engine module up on VCDS? I just went thru this and had to login with the cc number

Sent from my SM-G930V using Audizine mobile app

[alphaVR]

Just checked mine,

Cruise off, no pedals pressed 1000 0000
Cruise off, clutch pressed 1100 0000
Cruise off brake pressed 1011 0000
Cruise off both pressed 1111 0000

Looks like you got a normally closed clutch switch

I’d be willing to bet your anti lag works with the clutch out and disables with the clutch pressed also

Don't think I have anti-lag/launch control built into my tune. Need to get test pipes first... I paid way too much for my cats so I could pass emissions and don't want to melt them lol

Interesting on the cruise off, no pedals pressed output. Possible the replacement part that I got, even though its a p/n match (it supersedes the stock p/n), isn't correct?

Do you have a "G" in the software code when you pull the engine module up on VCDS? I just went thru this and had to login with the cc number

Sent from my SM-G930V using Audizine mobile app

Can't recall honestly. What was the login for?

[Zba]

Snow? You poor sob

[Robsa6]

Screenshot_20180415-191957.jpg check this out. Fixed my no cruise today with it hope it helps

Sent from my SM-G930V using Audizine mobile app

[alphaVR]

Snow? You poor sob

LOL well, yeah relative to Denver a little snow is nothing. We've already had 130" of snow this year... but its the middle of April. We should be having sunny 70-degree days like we had on Friday, not snowy 30-degree days like today.

Screenshot_20180415-191957.jpg check this out. Fixed my no cruise today with it hope it helps

Thats interesting. I'll check the software code tonight. It was working before I swapped out the switch and I haven't touched the ECU since late Sept so that leads me to believe it should be enabled, and that it may just be the switch is wrong in that it works backwards of what the ECU is expecting.

[Zba]

Just stick your head down there while manually testing all of the switches. Push and pull the plungers and see if the values change. It looks like your switch isn't adjusted properly based on your first set of values, but I'm not sure why your second set acts like "no pedal pressed" does.

The bit on adjustment
After installation, the vent valve must be in the following position:

a - 0-0.7 mm
1 - Pedal stop surface
2 - Pedal bracket
3 - Bracket
4 - Vent valve

[alphaVR]

Just stick your head down there while manually testing all of the switches. Push and pull the plungers and see if the values change. It looks like your switch isn't adjusted properly based on your first set of values, but I'm not sure why your second set acts like "no pedal pressed" does.

The bit on adjustment
After installation, the vent valve must be in the following position:

a - 0-0.7 mm
1 - Pedal stop surface
2 - Pedal bracket
3 - Bracket
4 - Vent valve

Far as I can tell the values are changing as the pedals are moved, so from an ECU perspective its working correctly there. I think the issue is either the adjustment or the sensor operating opposite of what it should. Youre saying that 1000, which im seeing when I push the clutch pedal down, is what i should see when the clutch pedal is NOT depressed?