DYI'ing ABS Module Repair

[NonRicer]

B6 A4 1.8T - Failing ABS module:

P0501 Vehicle Speed Sensor Code persists after changing front-left ABS sensor
ABS, ASC, CEL, & Brake warning lights illuminated on dash.
Speedometer does not work, but works temporarily after clearing DTC's with regular OBD scanner.

I was able to pull the ABS module without doing anything ridiculous like going in through the wheel-well. I used torx key set drivers which barely fit in place to remove all 6 T20 fasteners by only moving the PW reservoir to the side and pulling off the top half of the washer fluid reservoir (2003 model). I got the cover off using a razor knife, wasn't too hard but you could easily brick the module during this step if your blade slips and knicks the PCB inside.

Now all the angel hair wires are in view but BARELY visible to the naked eye even with 20/20 vision. Any attempt to solder these seems futile without special tools like a microscope and a precision solder kit. I cant immediately see any broken connections, will most likely buy a microscope and precision tip for my TS100 soldering iron; will be back with updates in a few days.

[Kevin C]

The fine wires are gold and typically have a long fatigue life. The thicker wires are aluminum and are known to break at the heal of the wirebond. You should be able to map out what wire bond to look at by the pin on the connector. The heavy aluminum wire bonds wont solder, you will need to make a jumper from copper to fix it.

[EuroxS4]

Microscope is a must and a good soldering iron the TS100 is a nice budget iron I use mine all the time. Wire that breaks is in the upper right hand corner most of the time. If you have a communication issue that is. Microscope will tell you which wire is broken. Just make sure you have good magnification and room to focus and solder.

[Ted222]

Before you dive head first down this dark rabbit hole..... You might want to have a look at something.
In your first picture, I can see you have a ton of corrosion in the connection socket. You might want to clean all these connection points first and then retest before you go down on the PCB board..
( have a look you see that greenish colored gunk..... "CORROSION")

[Protection]

Before you dive head first down this dark rabbit hole..... You might want to have a look at something.
In your first picture, I can see you have a ton of corrosion in the connection socket. You might want to clean all these connection points first and then retest before you go down on the PCB board..
( have a look you see that greenish colored gunk..... "CORROSION")

He is right!



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[NonRicer]

The fine wires are gold and typically have a long fatigue life. The thicker wires are aluminum and are known to break at the heal of the wirebond. You should be able to map out what wire bond to look at by the pin on the connector. The heavy aluminum wire bonds wont solder, you will need to make a jumper from copper to fix it.

Thanks for the heads up! I would’ve not have known that!


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[NonRicer]

He is right!



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Thanks for pointing that out, but I think the corrosion is not the issue. I had pulled the connector off a few weeks back and it was pristine in there. I had recently powered washed the engine and possibly got water into the connector harness which trickled down into the plug side of the module.
Same issue persisted prior the power washing.

[NonRicer]

So I found at-least 3 bad joints. But to be honest, idk if I can solder something that tiny.
I will still try though, I’m thinking my odds of success are slim to none.
Removing that silicone coating crap is a nightmare and some still stays behind so it will surely cook during soldering.

[Ted222]

WOW, you came this far..
If I have to do this anytime in the near future, I have a small 1080P mico-scope which works like a hot dam !!!!
I usually use it for mother board repairs and such, those wires and SMD ( surface mounted devices ) are not perceptible to the naked eye let alone the solder joints..
You'd be surprised how many broken solder joints I find ...
Keep us informed if your going to retest or replace this ABS controller, I'd like to know how it all turned out
CHeers, Ted

[NonRicer]

Still haven’t started this, I know I’m gonna brick it. I kind of regret not sending it in, but now I have no choice but to just go for it…

IMG_7471.jpg

[NonRicer]

So ended completely savaging the module and so bought new used one(circled red) described as 100% functional by eBay seller:
IMG_7522.jpg

If anyone has VCDS around 92010 I’ll pay


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[Hightekflytech]

So ended completely savaging the module and so bought new used one(circled red) described as 100% functional by eBay seller:
IMG_7522.jpg

If anyone has VCDS around 92010 I’ll pay


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I do, I’m in Ontario

[NonRicer]

So i just plugged in the new (used) ABS module to see what would happen.
Now, car start but cluster is totally dead and fans running on high. Same even when I unplug the module LOL

Would appreciate any input..


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