# Seeking advice.. ABS control module might be bad..



## Sam091990 (Dec 19, 2011)

05 A4 1.8 Quattro

My ABS, ESP, and BRAKE lights all turned on the other day. To me it seems like the lights are triggered when my headlights are turned on. Monday - drove about half a mile from work, turned my headlights on and all those lights showed up on the dash. Shut the car off for about 10 seconds and restarted, lights were all gone. Tuesday - cleared all the faults and left work, turned my headlights on after about a mile of driving and the lights showed up on the dash (there was maybe 4-5 key cycles before headlights were turned on). Wednesday (today) - cleared faults again and unplugged the ABS control module connector to make sure everything was good. Started the car up, put the headlights on and the lights appeared.

I installed Xentec 35W HID ballasts for the headlights and fog lights, but that was on January 7th. The only thing I did recently was put the car in service position to replace my power steering pump on Thursday (February 16th). Here's a list of the faults:

01 Engine Electronics | 18057 P1649 008 | Databus drivetrain missing message from ABS control module - intermittent
03 Brake Electronics | 18256 P1848 035 | Read event memory of engine CM - intermittent
03 Brake Electronics | 65535 000 | Control module defective - static
09 Electronic Central Electronics | 01312 079 | Drive train data bus, please read DTC - intermittent
25 Immobilizer | 01316 049 | Brake control module, no communication - intermittent

Part number on my ABS unit is 8E0 614 517 A. Definitely needs a new module? Do I have any options at this point besides paying $700 for a new control module?


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## Anony00GT (Mar 6, 2002)

Can you post a full scan?

Since it's tied into headlight operation and you've got headlights that aren't supposed to be on the car, let's not condemn the module right away. Verify powers and grounds to the ABS module, headlights off and headlights on. Make sure you're not somehow increasing resistance in the ABS module circuit due to the aftermarket headlights.

If all seems OK, then return all the lights to stock and see if the symptoms change.


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## Sam091990 (Dec 19, 2011)

Anony00GT said:


> Can you post a full scan?
> 
> Since it's tied into headlight operation and you've got headlights that aren't supposed to be on the car, let's not condemn the module right away. Verify powers and grounds to the ABS module, headlights off and headlights on. Make sure you're not somehow increasing resistance in the ABS module circuit due to the aftermarket headlights.
> 
> If all seems OK, then return all the lights to stock and see if the symptoms change.


Those were the only error in the full scan. I removed my HID ballasts and put the stock H7 bulbs back in and haven't had the lights pop up on the dash yet, so I'm hoping it's fixed.


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## GTijoejoe (Oct 6, 2001)

Sam091990 said:


> Those were the only error in the full scan. I removed my HID ballasts and put the stock H7 bulbs back in and haven't had the lights pop up on the dash yet, so I'm hoping it's fixed.


yeah, not a coincidence... you're probably having a voltage issue which is declaring a fault code and perhaps disabling the modulator to protect it.


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## oh3gti (Nov 19, 2011)

The control module is bad, the scan tool says it right there. Static faults won't go away, typically intermittent faults are caused by the static fault, or by disconnecting the battery etc. depending on how you wired the HID ballasts that could be the cause of the lights that is definitely an electrical problem, it seems like your headlight relay is grounding the ABS relay.


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## avanti284 (Apr 27, 2012)

*Can anybody help me?*

I have a similar problem with my 02 GTI 1.8T that could be caused by a bad ABS control module. My brake pedal pulsates at slow speeds just before coming to a stop and also in sharp turns. This has been going on since I bought my car 9 months ago but only recently has the pulsing been happening during normal braking time (i.e. it's getting worse) 

I cleaned my wheel speed sensors already with no luck and my OBD has no active or pending fault codes. Another problem that may be related to this is that my car's brake boost is very weak for the first 30 to 45 seconds after I start the engine. I explained both problems to a mechanic and he said to replace the brake booster. I did so but it didn't fix either problem. What's wrong with my brakes?


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## Anony00GT (Mar 6, 2002)

avanti284 said:


> I have a similar problem with my 02 GTI 1.8T that could be caused by a bad ABS control module. My brake pedal pulsates at slow speeds just before coming to a stop and also in sharp turns. This has been going on since I bought my car 9 months ago but only recently has the pulsing been happening during normal braking time (i.e. it's getting worse)
> 
> I cleaned my wheel speed sensors already with no luck and my OBD has no active or pending fault codes. Another problem that may be related to this is that my car's brake boost is very weak for the first 30 to 45 seconds after I start the engine. I explained both problems to a mechanic and he said to replace the brake booster. I did so but it didn't fix either problem. What's wrong with my brakes?


 You should start your own thread.. 

You're not going to see any ABS related faults if you're just using a generic OBDII scanner. You need VCDS to read the ABS module. 

Is this a mechanical brake pulsation, like a warped rotor, or a false ABS engagement? This has to be definitively determined first. If it's mechanical, fix accordingly. 

If it's a false ABS engagement, use VCDS to watch wheel speeds in measuring blocks. When the culprit wheel is identified, check the tone rings as well as the sensor.


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## avanti284 (Apr 27, 2012)

I've got my own thread here with more details as I'm still looking for help... 
http://forums.vwvortex.com/showthre...ne-is-cold-and-pedal-pulsating-at-slow-speeds 

Yes I did use a simple OBDII scanner at first but then I took my car to a "good" mechanic (they should at least be able to detect ABS faults with the appropriate scan tools) and he said that there is nothing wrong with the ABS. The diagnosis was instead a vacuum leak in the diaphragm of the brake booster but that was incorrect because I replaced it and I still have the problem. 

I don't have warped rotors, it's the ABS engaging when it shouldn't. Since the ABS pump definitely works (I can feel the pulsing, and it's quite strong), I suspect a wheel speed sensor but I cleaned all of the sensors and tone rings with brake cleaner with no luck.


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## Anony00GT (Mar 6, 2002)

Answered in your thread.


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