Suspected ABS sensor fault

[Lth0ms0n]

On my way home a few weeks ago, I got in the car to find the dash lit like a Christmas tree - with basically every electrical system off…

I’ve had a dodgy calliper (rear-right) which I assumed was the issue and replaced yesterday, but the issue persists…

OBD11 says there are 5 faults on the brake control unit:

• Rear-right ABS wheel speed sensor - incorrect component installed
• Rear-right ABS wheel speed sensor - incorrect component installed
• Tire pressure monitoring display - signal error
• Control module for electro-mechanical parking brake - wheel speed sensor implausible signal

They’re the most important ones…

I’m a bit up against it with this as it’s taken a few weeks to source the calliper. It looks like the rubber protector which covers the back of the handbrake connector has popped off (somehow) which makes me suspect a cable fault but at worst, it’s potentially a new handbrake motor.

I’m inclined to say the motor isn’t the issue. With the handbrake off, the wheel will turn but only just. As the calliper is new, I’m thinking the problem is the lack of clear info coming from that corner to allow the motor to release itself..

It’s more likely, I think, to be the ABS sensor. I’m just wondering if anyone else has encountered the same problem and has experience I can draw from, as I’m a bit short of time to really faff around changing parts unnecessarily.

I can get the cables and sensor in Aberdeen today but I’m hoping to god it’s not a problem with the handbrake motor.

 

[golfdave]

Lubricate the pad ears..they stick in the guides...then with the ignition on foot on the brake press & cycle the handbrake button on & off a couple of times...

Didn't you swap the pads/disc without using VCDS & instead removed the motor??...maybe thats the problem...

 

[Lth0ms0n]

Lubricate the pad ears..they stick in the guides...then with the ignition on foot on the brake press & cycle the handbrake button on & off a couple of times...

Didn't you swap the pads/disc without using VCDS & instead removed the motor??...maybe thats the problem...

I can't confirm what was done to the car when the pads and discs were replaced in 2019, that was done by a mechanic and not by myself. What I can say though, is I didn't have an issue with them at all prior to that - they first started squeaking (tell-tale sign) around 3 months later...

Where I'm at with it now is I've replaced the calliper, thinking it was totally bound on to the disc. It's been problematic for a while now (Assuming it was the issue) but upon removing it and dismantling it (thinking it was f*cked anyway) there are no sign of corrosion inside it. The only thing I noted was that some of the ball bearings appeared to be lying on the bottom of the piston body (and not in the screw-thread, where they belong) which might have been the reason it wasn't rotating correctly.

I had the entire thing off the car and last night, mounted the motor to the new calliper then re-attached with new pads and bled the brakes. I'll be honest, had no idea there was a VCDS programme for reversing it with and I'm kicking myself for not stopping to check, but I am where I am now.. In all honesty, I don't think the calliper was ever the issue and since replacing it hasn't cleared any of the faults (and the only faults listed pertain to the back-right wheel and not all 4, which means I don't think it's the entire ABS system which is the problem) I think it's been left out of sync by the mechanic..

All I can do now is try and figure my way out of the mess I'm in, one piece at a time. I've got the new ABS sensor for it and I'll fit that to it tonight. I want to run the process through my OBD11, BUT, while the part of me that knows it's out of sync with the pads says to take the motor off the calliper, reverse it and then re-fit it before running it forwards again, reading on Ross Tech's website (and the advice from the OBD11 app itself) you need to have it all on the car before proceeding with it, so I'm unsure what to do next as far as that part of it's concerned..

The pads are definitely not relaxed off the disc at the moment, I know that much. A short run at lunchtime today was enough to get it up to piping hot. My concern is, if I leave the calliper as-is then reverse/forward it, am I risking the motor trying to wind itself back beyond where the piston is feasibly going to go and will I break it, or does it have the sav built-in to know when to stop? I haven't been able to find any confirmation online of how it knows where it's position is - if it uses pressure sensors to read the feedback from the disc or if there are hard-wired position markers inside the motor itself, like there are on the ones used by the flaps on the HVAC system?

 

[golfdave]

As I stated before you need to cycle the parking brake on & off for it to adjust the pad clearance & reset itself...the motors have no "stops"..it only measures current draw to determine its "position"..(info from the ERWIN workshop books).

It sounds like the pads are sticking in the guides also..this is a common problem...just remove & re-grease the back plates & the ears..Info here when I did my whole braking system!

Post 85 & 87 here:-

VW Golf MK7 Estate, GT spec, Tungsten Silver, 1.4TSI | Page 6 | GOLFMK7 - VW GTI MKVII Forum / VW Golf R Forum / VW Golf MKVII Forum

 

[Lth0ms0n]

As I stated before you need to cycle the parking brake on & off for it to adjust the pad clearance & reset itself...the motors have no "stops"..it only measures current draw to determine its "position"..(info from the ERWIN workshop books).

It sounds like the pads are sticking in the guides also..this is a common problem...just remove & re-grease the back plates & the ears..Info here when I did my whole braking system!

Post 85 & 87 here:-

VW Golf MK7 Estate, GT spec, Tungsten Silver, 1.4TSI | Page 6 | GOLFMK7 - VW GTI MKVII Forum / VW Golf R Forum / VW Golf MKVII Forum

Thanks Dave, I'll take a read through those later - I've had a quick look now, too much to take in on a sneaky glance when I should probably be working!

I've cycled the parking brake a few times but no dice - will grease the pads as you advise, assuming it's better to get some dedicated brake grease or will "normal" stuff do the trick, also?

 

[golfdave]

Thanks Dave, I'll take a read through those later - I've had a quick look now, too much to take in on a sneaky glance when I should probably be working!

I've cycled the parking brake a few times but no dice - will grease the pads as you advise, assuming it's better to get some dedicated brake grease or will "normal" stuff do the trick, also?

you need the proper stuff as I've used many other types over the years including ceramic greases..& they just calcify....all info in those posts...

if the cycling hasn't helped I reckon that the motor can't properly retract the spindle so either its become disengaged or the as a long shot the piston seals have driven & baked hard causing the piston to stick.....ie the whole caliper is FUBAR.....I'v done caliper strip downs & replaced seals etc...cheap, & requires some time..in your case it might be better to get a whole new caliper & follow the procedure properly..as stated on Ross-Tech

 

[Lth0ms0n]

you need the proper stuff as I've used many other types over the years including ceramic greases..& they just calcify....all info in those posts...

if the cycling hasn't helped I reckon that the motor can't properly retract the spindle so either its become disengaged or the as a long shot the piston seals have driven & baked hard causing the piston to stick.....ie the whole caliper is FUBAR.....I'v done caliper strip downs & replaced seals etc...cheap, & requires some time..in your case it might be better to get a whole new caliper & follow the procedure properly..as stated on Ross-Tech

Ok, will nip out for some of that later then..

It's a new calliper so I doubt there's anything wrong with the seals. If there are no position sensors then I'm free to run through the procedure once I'm done at my desk this afternoon and (hopefully) that will resolve it.

 

[golfdave]

Ok, will nip out for some of that later then..

It's a new calliper so I doubt there's anything wrong with the seals. If there are no position sensors then I'm free to run through the procedure once I'm done at my desk this afternoon and (hopefully) that will resolve it.

I also suggest going for a short drive as some of the fault codes will only clear once the car has been driven around the block so it can self test...regardless of what you try in VCDS etc..

 

[IWMTom]

• Rear-right ABS wheel speed sensor - incorrect component installed

That codes is clear. Has the ABS sensor been swapped at any point? There are two different types, one for with ACC and one for without. One is black, the other is grey.

 

[golfdave]

• Rear-right ABS wheel speed sensor - incorrect component installed

That codes is clear. Has the ABS sensor been swapped at any point? There are two different types, one for with ACC and one for without. One is black, the other is grey.

I passed that...(twat).....thing is this should have thrown it straight away as soon as it was fitted & the car was driven.

I recon somebodies been messing with it & not known WTF they were doing...

 

[Lth0ms0n]

• Rear-right ABS wheel speed sensor - incorrect component installed

That codes is clear. Has the ABS sensor been swapped at any point? There are two different types, one for with ACC and one for without. One is black, the other is grey.

I fixed it

No replacement, that would be the original sensor - which is either caked in shit (from years of trawling up and down to the south coast from Aberdeen) or knackered by excess heat (from the disc the day the fault developed).

In all honesty, in all the scans I’ve done on the car since it happened, I can’t think that this error has come up before but I could be wrong. When I saw it this morning, I suspected this was the issue… I think it’s been slowly giving me grief for a while, I’ve had a few false positives from the types pressure monitoring which, looking back (although there were usually slight variations in the pressure on the corner when I checked it afterwards) was probably the first sign of trouble from it..

That was just before I really started any DIY on the car.

I’m waiting for a new wiring loom for the back-right corner, to replace the one where the rubber thing has popped off before it causes any more problems..

Dave, followed all your advice from earlier - both callipers have been reversed and greased with copper. It could probably use a few more cycles of the parking brake but there’s no noise or excess heat coming from it after a run tonight, as far as I can see.

So that’s a relief - it will make it back down the road this weekend with a boot full of crap, without running the risk of rear-ending someone (no ABS) or my losing my license (no ACC).

 

[golfdave]

I fixed it



No replacement, that would be the original sensor - which is either caked in shit (from years of trawling up and down to the south coast from Aberdeen) or knackered by excess heat (from the disc the day the fault developed).

In all honesty, in all the scans I’ve done on the car since it happened, I can’t think that this error has come up before but I could be wrong. When I saw it this morning, I suspected this was the issue… I think it’s been slowly giving me grief for a while, I’ve had a few false positives from the types pressure monitoring which, looking back (although there were usually slight variations in the pressure on the corner when I checked it afterwards) was probably the first sign of trouble from it..

That was just before I really started any DIY on the car.

I’m waiting for a new wiring loom for the back-right corner, to replace the one where the rubber thing has popped off before it causes any more problems..

Dave, followed all your advice from earlier - both callipers have been reversed and greased with copper. It could probably use a few more cycles of the parking brake but there’s no noise or excess heat coming from it after a run tonight, as far as I can see.

So that’s a relief - it will make it back down the road this weekend with a boot full of crap, without running the risk of rear-ending someone (no ABS) or my losing my license (no ACC).

Glad you sorted it..just remember to use the correct procedure using VCDS OBDII to retract the spindles before dismantling the calipers to get the pads/discs off etc..

I didn't mention copper grease as a recommendation as its not 100% ideal with these sensitive ABS systems IF it gets on to the sensor,...

""TRW make a specific grease for their callipers called PFG-110. - I used the TRW grease on both the guide pins & bush, & then used Loctite LB8009 (in USA it is called “Heavy Duty”) on all pad backing plate to caliper/bracket contact/slide points."