[Warning Light] ABS warning light - possible broken cable???

[benwalk15]

Hi all,

This is my first post so bear with me..

I have a 2015 Berlingo Enterprise B9 panel van which I've owned a couple of months now and am extremely pleased with. However, recently the ABS/traction warning light has been coming on intermittently (once a week at most). So I went ahead and scanned the ABS module with the appropriate equipment and it showed error "C0040 - brake pedal switch fault: coherence with the pressure sensor". So assumed the brake light switch needed changing at some point...

Then all of a sudden the ABS warning light was on permanently, so I thought I best fix and went ahead and bought a new pedal switch. Once I went through all the faff of realising the switch is actually under the glove box in a little box and getting it changed, I was hoping that would be the end of it. Oh no, upon erasing the error codes a NEW code appeared: "C1335 rear RH wheel speed sensor signal fault".

So I thought, I would just get a new sensor and install. Pretty easy task, jack it up, wheel off, take old sensor off and put new one on and connect up, which I did with relatively little bother (have done this stuff before).

Started up and still flashing up with warnings. Erased the fault codes, restarted, still getting ABS warning - rear RH speed sensor!!   

Just to make sure I changed the correct sensor I disconnected the left one, sure enough that threw up rear LH sensor fault. Upon reconnecting it, the fault went away as expected. I then put a multimeter across the socket for the sensor on the right (faulty) side and read no resistance (open circuit), the left read something like 0.866 ohm.

So, is this a common issue? It would present itself to me like a brake in the cable somewhere but could it possibly be a ABS ECU issue? Can anyone offer any advise on where to start looking to resolve such an issue?

Thanks in advance!!

[ntm1275]

I've had this a couple of times on mine and I found the issue was down to rust underneath the sensor. The rust was pushing the sensor out of alignment.
I took the sensor off and then used a centre punch to gently chip of the rust until all the loose flakes were gone and the area was back to being nearly flat.
Refitted the sensor, cleared the error codes and then it was all back to normal.
This may not be the same issue for you, but it's worth checking.

[benwalk15]

Thanks ntm1275. I did think this could be a potential cause as well, as I saw a youtube of someone else having the same problem. But mine wasn’t too rusty really (although there was a little there I scraped off with a flat head screwdriver).

I think the fact it reads open circuit on the failed side and show resistance on the working side, it can only be a cable/connector issue (or at worst abs module).

I saw this page https://www.aaronsautos.co.uk/citroen-be...ing-fault/ when searching online so might get the passenger seats out and have a look under there!

Will keep the post up to date with my findings!
Ben

[benwalk15]

All sorted now. As expected, was a damaged cable close to the connector! Stripped back, soldered, heat shrink and insulated = ABS fault codes gone!!! 

Here was the culprit:

[jj9]

Well done finding the damaged wire, how did you manage to trace it down?


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[benwalk15]

Thank you! I first started by taking the front passenger seats out and lifting the carpet to check all the wiring there (as per link above), but it all looked fine..

Next I removed the passenger wheel arch liner to expose the abs pump/ecu. Again, all looked ok there too.

I then disconnected the multi plug from the abs unit and prized the cover off to reveal what colours went to which pin and put a piece of copper wire between the red/blue cables to effectively short them together.

I went back to the rear wheel and put a meter across the two pins on the abs sensor connector and set the meter to continuity/resistance. I started wiggling the wire and noticed the resistance jumping around when I moved the connector, so stripped back the plastic conduit and the problem revealed itself!

Relieved is putting it mildly haha.. just have to put all the interior back together now.. although by removing the passenger seat bench it has given me a good opportunity to give it a much needed clean under there haha!!

[jj9]

A great bit of fault finding work there,  I like to read of faults being cured using good old detective work combined with common sense.   


Excellent result.


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[digi-tal]

All sorted now. As expected, was a damaged cable close to the connector! Stripped back, soldered, heat shrink and insulated = ABS fault codes gone!!! 

Here was the culprit:

Thanks for this, saved me loads of messing around! Mine had gone in exactly the same place, garage said they couldn’t find the fault and I’d got 2 days left on my MOT!

[benwalk15]

All sorted now. As expected, was a damaged cable close to the connector! Stripped back, soldered, heat shrink and insulated = ABS fault codes gone!!! 

Here was the culprit:

Thanks for this, saved me loads of messing around! Mine had gone in exactly the same place, garage said they couldn’t find the fault and I’d got 2 days left on my MOT!

That's awesome! Really pleased I was able to help someone out with a similar problem 

[djewen]

I would like to thank you for your efforts in finding this issue. I had the same fault and began to notice a pattern of intermittency when hitting bumps in the road so I was sure there was a cable fault.

I too read the above article where the seats were removed etc but went straight to the location where you found the issue and sure enough I had the same fault, although not at first, I missed it on the first pass and didn’t get it until checking closely again. This makes three of us in this thread.

There was a tiny break in the cable at one of the points where it’s secured to the body via cable tie clip, in my case this tie was extremely tight and appears to have been to route cause of the failure, note the  link in the cables, you can see the corrosion where I have stripped back the sheath so this has be a fault developing over time.

I stripped back, repaired, rebuilt, cleared the fault codes then went for a road test. No more fault and my cruise control is back working.