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ESP/ASR system, ABS braking system, parking brake, tyre under inflation faults

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lima71   
Wed Sep 14 2022, 07:16am
Member No: #60098
Joined: Sep 14 2022
Location: Slovenia
Citroguy wrote ...

Forgive me if this post is in too much detail as some will know how to do what I’m explaining already and some may need more info.
So I had the exact same faults as this one on my 2015 gc4p,

ESP/ASR system
ABS braking system
parking brake
tyre under inflation fault
Anti roll back failed
Cruise control will not work
Sat nav frozen.

at first it was intermittent, and would reset after I switched off and restarted the car. After a couple of months it then showed these faults all the time Then COVID hit and I just dealt with it annoying me all the time. Once I could get it booked in for its service the garage hooked it up for me and told me it was showing a fault on the rear offside ABS sensor which they then tested and showed 0v. I done a bit more research and found something on the auto handbrake unit which the guy showed you where the cable had broken (different circuit, but I thought maybe the same area) so I stripped the back wheel off and proceeded to check the voltage (pin 1 is 11v supply) on the ABS connector - sure enough 0v, I then removed the clips on the plastic conduit leading from the rear wheel to just before the fuel tank. Then pulled the conduit off and checked the cables, the twisted pair is for the ABS sensor, the yellow in the twisted pair should show 11v dc when the car is on (press the start button without pressing the brake pedal and leave on while testing) there is another yellow cable which is for the auto brake unit - this is NOT twisted and you don’t need to touch that one. Once you have the twisted pair showing, check along the twisted yellow cable for any green spots (Copper oxidisation), it may not look overly obvious, but if it’s there you should see it. If you find it you will know by pulling on that little bit - mine just separated once the rest of the insulation broke. Once found strip a little of the insulation back on the cable coming from the front of the car and test, if you have 11v then you know the rest of the cable is ok then you can strip and connect using a shrink connector or personally I just twisted the cable the correct way and soldered and used heat shrink to cover the joint and then tested the connector - 11v was there. I recovered the cable with the conduit and connected everything back together etc using electrical tape where the fabric material had been, (I'll keep checking this and get something longer lasting if needed). Tested the car and all faults are gone. Happy days! 😀



lima71   
Wed Sep 14 2022, 07:25am
Member No: #60098
Joined: Sep 14 2022
Location: Slovenia
Great information! Same problem! Solved in 1/2 hour! Sincere THANK YOU! i give for beer!
Wutang   
Wed Sep 14 2022, 09:54am
Member No: #46858
Joined: Nov 24 2016
Location: London
Get the wiring to the sensor checked, I and many others have had this fault. normally the wiring at fault not the sensor but the diagnostics read it as a sensor failure.
vimes   
Sun Feb 19 2023, 06:10am
Member No: #60511
Joined: Feb 19 2023
Location: Essex
Citroguy wrote ...

Forgive me if this post is in too much detail as some will know how to do what I’m explaining already and some may need more info.
So I had the exact same faults as this one on my 2015 gc4p,

ESP/ASR system
ABS braking system
parking brake
tyre under inflation fault
Anti roll back failed
Cruise control will not work
Sat nav frozen.

at first it was intermittent, and would reset after I switched off and restarted the car. After a couple of months it then showed these faults all the time Then COVID hit and I just dealt with it annoying me all the time. Once I could get it booked in for its service the garage hooked it up for me and told me it was showing a fault on the rear offside ABS sensor which they then tested and showed 0v. I done a bit more research and found something on the auto handbrake unit which the guy showed you where the cable had broken (different circuit, but I thought maybe the same area) so I stripped the back wheel off and proceeded to check the voltage (pin 1 is 11v supply) on the ABS connector - sure enough 0v, I then removed the clips on the plastic conduit leading from the rear wheel to just before the fuel tank. Then pulled the conduit off and checked the cables, the twisted pair is for the ABS sensor, the yellow in the twisted pair should show 11v dc when the car is on (press the start button without pressing the brake pedal and leave on while testing) there is another yellow cable which is for the auto brake unit - this is NOT twisted and you don’t need to touch that one. Once you have the twisted pair showing, check along the twisted yellow cable for any green spots (Copper oxidisation), it may not look overly obvious, but if it’s there you should see it. If you find it you will know by pulling on that little bit - mine just separated once the rest of the insulation broke. Once found strip a little of the insulation back on the cable coming from the front of the car and test, if you have 11v then you know the rest of the cable is ok then you can strip and connect using a shrink connector or personally I just twisted the cable the correct way and soldered and used heat shrink to cover the joint and then tested the connector - 11v was there. I recovered the cable with the conduit and connected everything back together etc using electrical tape where the fabric material had been, (I'll keep checking this and get something longer lasting if needed). Tested the car and all faults are gone. Happy days! 😀


Thank you.

This weekend while visiting family we got the list of faults above. It got worse at one point as it decided to throw an engine fault, we got the red STOP message, lost power steering, no speedo reading and wouldn't go above 3rd gear etc.

The codes were related to the ABS ( P0500 - Vehicle speed malfunction and U0415 - Invalid data from the ABS control system). To get going again e we disconnected the battery and reconnected it. Fortunately, this reset the car, cleared the red STOP light and allowed us to drive again.

So back home today, followed the above guidance and found the green spots on the twisted yellow wire. They're really not obvious and I would have been chasing this for hours/days if it wasn't for this forum.

Needless to say, the wire was corroded internally but not fully broken - had super high resistance and fell apart when I pulled it.

New bit of wire and everything is sorted, all error codes/warnings gone and car back to usual.

Just wanted to say thank you!
texaspetey   
Fri Apr 14 2023, 04:26am
Member No: #60676
Joined: Apr 14 2023
Location: Suffolk
Thank you so much - exactly the same issue on the same rear offside abs yellow wire. Stumped a garage I took it to who said the ABS sensor was fine, and said they had looked at the wires they could access and gave me contact details for a specialist electronics garage. When I found and followed your solution it was clear the garage hadn't looked at the wires at all as the conduit was untouched from the day it left the factory. Only difference to you is I used cable ties to secure the conduit back in place of the the original material tape.

Thanks once again!

Citroguy wrote ...

Forgive me if this post is in too much detail as some will know how to do what I’m explaining already and some may need more info.
So I had the exact same faults as this one on my 2015 gc4p,

ESP/ASR system
ABS braking system
parking brake
tyre under inflation fault
Anti roll back failed
Cruise control will not work
Sat nav frozen.

at first it was intermittent, and would reset after I switched off and restarted the car. After a couple of months it then showed these faults all the time Then COVID hit and I just dealt with it annoying me all the time. Once I could get it booked in for its service the garage hooked it up for me and told me it was showing a fault on the rear offside ABS sensor which they then tested and showed 0v. I done a bit more research and found something on the auto handbrake unit which the guy showed you where the cable had broken (different circuit, but I thought maybe the same area) so I stripped the back wheel off and proceeded to check the voltage (pin 1 is 11v supply) on the ABS connector - sure enough 0v, I then removed the clips on the plastic conduit leading from the rear wheel to just before the fuel tank. Then pulled the conduit off and checked the cables, the twisted pair is for the ABS sensor, the yellow in the twisted pair should show 11v dc when the car is on (press the start button without pressing the brake pedal and leave on while testing) there is another yellow cable which is for the auto brake unit - this is NOT twisted and you don’t need to touch that one. Once you have the twisted pair showing, check along the twisted yellow cable for any green spots (Copper oxidisation), it may not look overly obvious, but if it’s there you should see it. If you find it you will know by pulling on that little bit - mine just separated once the rest of the insulation broke. Once found strip a little of the insulation back on the cable coming from the front of the car and test, if you have 11v then you know the rest of the cable is ok then you can strip and connect using a shrink connector or personally I just twisted the cable the correct way and soldered and used heat shrink to cover the joint and then tested the connector - 11v was there. I recovered the cable with the conduit and connected everything back together etc using electrical tape where the fabric material had been, (I'll keep checking this and get something longer lasting if needed). Tested the car and all faults are gone. Happy days! 😀

Farmerguy   
Fri Apr 14 2023, 06:26am
Member No: #59597
Joined: Apr 10 2022
Location: Denmark west part
Twisted wires are can-bus wires.
Hard to check without oscilloscope.
Why do this happen?
Well there is one signal, the speed signal, this is used by esp, abs, electronic handbrake and of course cruise control, it tells the car if it is moving, and how fast it is moving, if it does not have this signal, it need to decouple these systems, so it dont get into a dangerous situation.

Eks: my Saab had a abs fault, then i could not communicate with abs module, i removed the connector at the abs module, put it back in, then there was no problem.

Ok the c4 gp b58 the abs module sits right in front of left front wheel, not exactly a great position if salt water managed to get to the connector.

What i have understood though about this, if that if the can bus becomes damaged, corrosed at one point in the ring, what is on this bus wont really work properly.
routemaster1   
Fri Apr 14 2023, 06:45am
Member No: #574
Joined: Jul 08 2007
Location: Dorset
The tyre pressure system also works fromthe ABS sensors. After initiallisation the car's system knows the relative wheel rotation speeds from the information the abs sensors obtain. If one tyre loses pressure the rolling diameter decreases and the rotation speed increases. After a time the system will start throwing warnings. If one sensor is supplying odd inf, I guess the system understands and gives an error message.

Note that the system does not detect a tyre which has deflated completely overnight, or a sudden deflation; it is useful to detect relatively slow punctures. Also it doesn't tell you which tyre is deflating. However, this type of system can do so if the manufacturers cared to put in the effort to write the software.
Farmerguy   
Fri Apr 14 2023, 09:04am
Member No: #59597
Joined: Apr 10 2022
Location: Denmark west part
routemaster1 wrote ...

The tyre pressure system also works fromthe ABS sensors. After initiallisation the car's system knows the relative wheel rotation speeds from the information the abs sensors obtain. If one tyre loses pressure the rolling diameter decreases and the rotation speed increases. After a time the system will start throwing warnings. If one sensor is supplying odd inf, I guess the system understands and gives an error message.

Note that the system does not detect a tyre which has deflated completely overnight, or a sudden deflation; it is useful to detect relatively slow punctures. Also it doesn't tell you which tyre is deflating. However, this type of system can do so if the manufacturers cared to put in the effort to write the software.


Do you know if the 2006-2013 c4 gp use such system? I wonder if that can be activated on mine, i have not found an antenna for the tpms valves so i assumed it didnt have this system.
routemaster1   
Fri Apr 14 2023, 12:34pm
Member No: #574
Joined: Jul 08 2007
Location: Dorset
Farmerguy wrote ...

routemaster1 wrote ...

The tyre pressure system also works fromthe ABS sensors. After initiallisation the car's system knows the relative wheel rotation speeds from the information the abs sensors obtain. If one tyre loses pressure the rolling diameter decreases and the rotation speed increases. After a time the system will start throwing warnings. If one sensor is supplying odd inf, I guess the system understands and gives an error message.

Note that the system does not detect a tyre which has deflated completely overnight, or a sudden deflation; it is useful to detect relatively slow punctures. Also it doesn't tell you which tyre is deflating. However, this type of system can do so if the manufacturers cared to put in the effort to write the software.


Do you know if the 2006-2013 c4 gp use such system? I wonder if that can be activated on mine, i have not found an antenna for the tpms valves so i assumed it didnt have this system.


The system with the sensors in each wheel is the 'direct' system and will be very difficult to retro-fit. The 'indirect' system uses the abs sensors. I can't remember whether my 2011 C4GP had it or not. Again, if it isn't present it would probably be difficult to amend the software.
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