B8 3.0tdi abs/suspension/parking brake warnings

[bhodgkiss]

Hi All

When my B8 3.0tdi gets wet (driving through heavy water) the esp/parking brake/suspension fault lights comes on.

Originally VCDS said front left abs sensor, so I swapped it for another Bosch item and cleared it for a few months.

It’s now happened again after driving in heavy rain.

When I plug in VCDS I get the LH front abs sensor fault again (implausible signal, G47) and also ‘control module for elec park/handbrake - J540 - check dtc memory’

I’d be surprised if it was the abs sensor again already.

Any ideas please, as it definitely coincides with driving in the wet.

It normally corrects itself but hasn’t this time.

I don’t have an undertray, which is obviously not ideal.

I’ll also check the battery voltage....

Thanks
Ben

 

[bhodgkiss]

Items i've written down to check so far, based on forum searches:

- Corrosion on ESP module in passenger footwell, below opening from cabin air filter
- Check for blown fuses
- Try braking hard to clear it!
- Loose connector in passenger footwell, possibly kicked by accident
- Brake light switch
- ABS wiring to control module (looked last time and found nothing). Its the Front left shown in VCDS but ABS sensor has been swapped recently
- ABS sensor connector wet from driving through puddles (it does only happen when its wet.....). Not at shrouded as it could be, especially with undertray not being fitted
- Debris build up end of ABS sensor.... bit of a faff to check
- Check battery voltage and connections
- Steering angle sensor check (I'll check VCDS first)
- Water ingress into ECU box - checked this last time and was dry.....

 

[desertstorm]

Just out of interest have you tried looking at the measuring blocks in the ABS module for the wheel speed sensors. You can monitor all 4 at the same time and they should all be pretty much the same. Check the sensor is still mounted in the correct place and the correct distance from the back of the bearing.

 

[bhodgkiss]

Thanks Karl

Will do, I guess checking the sensor position isn't easy - but provided it's fully home with the nut clamping it against the upright, it can't be in the wrong place? I'll try removing it (without breaking it) to check the end is still ok. It wasn't installed long ago.

Anyone else had similar problems please? It does seem to be wet weather related ...

 

[Ginge247]

Thanks Karl

Will do, I guess checking the sensor position isn't easy - but provided it's fully home with the nut clamping it against the upright, it can't be in the wrong place? I'll try removing it (without breaking it) to check the end is still ok. It wasn't installed long ago.

Anyone else had similar problems please? It does seem to be wet weather related ...

I'd say there is probably water either getting into the connection point or you may have a nick in the wiring letting water in. As you seem to have covered everything else.

Sent from my JSN-L21 using Tapatalk

 

[bhodgkiss]

Many thanks
I still need to check that big list above, I'll tackle it over the weekend!

 

[bhodgkiss]

Ok so the end of the abs sensor was machined through. Down to the metalwork inside

I'd post a pic but photobucket says my storage is full

Anyway I'll get it swapped

Obviously I need to understand what's rubbed - when I removed the original sensor I had to drill it out, so perhaps some swarf etc fell into the cavity and has been whizzing round and jamming between sensor head and the ring on the cv joint...

Tried hoovering it out as best I can with a tube poked down the hole

Hmmm not ideal.

All connectors look fine otherwise so not fully sure why it seems to give up when wet.

At this rate I'll fit a new sensor and the same will happen again? Possibly it just all needs taking apart properly...

 

[youngy93]

whenever i have replaced my wheel speed sensors, i snap the top off and put a self tapper down the middle of the sensor then pull it out with a claw hammer

 

[bhodgkiss]

Many thanks
Yes after the drill didn't seem to work as well as expected I did exactly that with a self tapper - just not sure if anything fell in.

I don't believe I had the wrong sensor But seems odd it's rubbed