Steve-V6-D61
New Member
Clio ABS INFO found and gathered from the inter web that may help others.
I have two faults, which show how serial data should be interpreted with care and lateral thinking.
The first problem involved is about a month ago the ABS light would illuminate intermittently when driving. When checking the DTC register, the error code (0203 - instrument panel circuit error) was present when the ABS MIL lamp was on.
The ABS system in question is Bosch 5.3 TCS. The system employs an integrated hydraulic modulator, or valve block, containing the solenoids, the ABS PCM, including the pump, and PCM relays. The key issues to keep in mind with this and many other vehicles produced today is that they contain several systems which share sensor in¬puts and control functionality. My vehicle does not, however, have a CAN interface, which would normally broadcast all relevant information to be shared with the relevant PCMs.
The systems that would have control functionality sharing are the ABS traction control system, and engine management, which require wheel speed in-puts ¬the engine management requires wheel speed in-puts for the DBW (Drive by Wire) Throttle control.
Hence the speed interface unit in the boot for speedometer and injection control signal splitting..
The DTC 0203 seems to suggest an error on the ABS pins 10/21, both of which go to the instrument panel. Removing the instrument binnacle was relatively easy and checking continually on both circuits revealed no problems. I also checked for short to ground on the ABS bulb circuit.
So far so good, though I did notice that when back probing the ABS modulator socket (which, incidentally, has to be stripped to gain access to the pins), the relays could be heard clicking, suggesting a poor connection in either the socket or PCM. I also confirmed that the MIL lamp could be induced on or off by the same process. After inspection of the pins suggested that there was no poor contact or corrosion, my conclusion was that of an internal PCM error/dry joint, as all power and ground references were excellent. Not wishing to replace the ABS unit at a cost of £1600, I bypassed the error, providing an independent ground to pin 21. The ABS system now appeared to operate normally, though the self check lamp did not go through its self test function correctly - a MOT failure issue.
Finally getting my brain back into gear, we attached a code reader to the serial port and checked all data/DTCs in all systems. The result: ABS DTC 0203, navigation system - no errors; engine management -:- no errors. Not much good really, so we decided to check the fidelity of the ABS wheel sensors, i.e. the correct signal profile and amplitude. All wheel speed in-puts were excellent, so the next test was to check live data using the laptop.
The ABS system was fine apart from
Biting the bullet, I replaced the ABS modulator including bleeding the brakes.
I have also learned a hell of a lot about integrated signal plausibility and the value of comparing live serial data
So what have I learned?
1) Don't expect the dealerships to know more than you.
2) Fix known faults first before looking for others.
3) Don't bodge repairs.
4) Don't rely on serial DTCs.
Don't judge a repair based on cost
This vehicle is fitted with a BOSCH 5.3 ABS of the four channel additional type; the conventional braking equipment and the ABS equipment are separate.
SPECIAL NOTES
The system comprises four speed sensors. Each hydraulic braking channel is associated with a sensor at each wheel. The front wheels are therefore regulated separately. The rear wheels however are regulated at the same time and in the same way according to the select low principle (the first wheel tending to lock causes immediate regulation on the complete axle assembly). On this vehicle, the brake limiter is not fitted and its role is performed by a specific program located in the ABS unit computer called EBD (Electronic Braking
Distribution.
The system equipping this vehicle has neither the electronic stability program (ESP) function nor the antispin (Traction Control) regulation (ASR) function.
WARNING
If the ABS fuse is removed or the ABS light is ON, do not brake sharply during driving as the electronic braking distribution function is no longer active (the brake pressure is the same in the front and rear) and there is a high risk of skidding and or crashing due to unbalanced braking effect.
A new ABS unit from Renault is £1600, yes twice the price of other cars, no surprise there, but there are many companies on the web that offer a repair service for the ABS unit on the back of the pump unit, there are a lot of problems with these units so be warned.
ABS pump module removal:
We normally only ever need the electronic part of the ABS pump, this is atatched to the side of the pump with six torx screws and can be removed easily. The best way to access the module is to first remove the passenger side front wheel and the inner wheel arch plastic liner, then the washer bottle can be unbolted and moved out of the way giving access to the six torx screws. Remember you can still drive the car with the module removed - you will have conventional braking but with no ABS function and the light will remain on untill the remanufactured module is refitted.
I have two faults, which show how serial data should be interpreted with care and lateral thinking.
The first problem involved is about a month ago the ABS light would illuminate intermittently when driving. When checking the DTC register, the error code (0203 - instrument panel circuit error) was present when the ABS MIL lamp was on.
The ABS system in question is Bosch 5.3 TCS. The system employs an integrated hydraulic modulator, or valve block, containing the solenoids, the ABS PCM, including the pump, and PCM relays. The key issues to keep in mind with this and many other vehicles produced today is that they contain several systems which share sensor in¬puts and control functionality. My vehicle does not, however, have a CAN interface, which would normally broadcast all relevant information to be shared with the relevant PCMs.
The systems that would have control functionality sharing are the ABS traction control system, and engine management, which require wheel speed in-puts ¬the engine management requires wheel speed in-puts for the DBW (Drive by Wire) Throttle control.
Hence the speed interface unit in the boot for speedometer and injection control signal splitting..
The DTC 0203 seems to suggest an error on the ABS pins 10/21, both of which go to the instrument panel. Removing the instrument binnacle was relatively easy and checking continually on both circuits revealed no problems. I also checked for short to ground on the ABS bulb circuit.
So far so good, though I did notice that when back probing the ABS modulator socket (which, incidentally, has to be stripped to gain access to the pins), the relays could be heard clicking, suggesting a poor connection in either the socket or PCM. I also confirmed that the MIL lamp could be induced on or off by the same process. After inspection of the pins suggested that there was no poor contact or corrosion, my conclusion was that of an internal PCM error/dry joint, as all power and ground references were excellent. Not wishing to replace the ABS unit at a cost of £1600, I bypassed the error, providing an independent ground to pin 21. The ABS system now appeared to operate normally, though the self check lamp did not go through its self test function correctly - a MOT failure issue.
Finally getting my brain back into gear, we attached a code reader to the serial port and checked all data/DTCs in all systems. The result: ABS DTC 0203, navigation system - no errors; engine management -:- no errors. Not much good really, so we decided to check the fidelity of the ABS wheel sensors, i.e. the correct signal profile and amplitude. All wheel speed in-puts were excellent, so the next test was to check live data using the laptop.
The ABS system was fine apart from
Biting the bullet, I replaced the ABS modulator including bleeding the brakes.
I have also learned a hell of a lot about integrated signal plausibility and the value of comparing live serial data
So what have I learned?
1) Don't expect the dealerships to know more than you.
2) Fix known faults first before looking for others.
3) Don't bodge repairs.
4) Don't rely on serial DTCs.
Don't judge a repair based on cost
This vehicle is fitted with a BOSCH 5.3 ABS of the four channel additional type; the conventional braking equipment and the ABS equipment are separate.
SPECIAL NOTES
The system comprises four speed sensors. Each hydraulic braking channel is associated with a sensor at each wheel. The front wheels are therefore regulated separately. The rear wheels however are regulated at the same time and in the same way according to the select low principle (the first wheel tending to lock causes immediate regulation on the complete axle assembly). On this vehicle, the brake limiter is not fitted and its role is performed by a specific program located in the ABS unit computer called EBD (Electronic Braking
Distribution.
The system equipping this vehicle has neither the electronic stability program (ESP) function nor the antispin (Traction Control) regulation (ASR) function.
WARNING
If the ABS fuse is removed or the ABS light is ON, do not brake sharply during driving as the electronic braking distribution function is no longer active (the brake pressure is the same in the front and rear) and there is a high risk of skidding and or crashing due to unbalanced braking effect.
A new ABS unit from Renault is £1600, yes twice the price of other cars, no surprise there, but there are many companies on the web that offer a repair service for the ABS unit on the back of the pump unit, there are a lot of problems with these units so be warned.
ABS pump module removal:
We normally only ever need the electronic part of the ABS pump, this is atatched to the side of the pump with six torx screws and can be removed easily. The best way to access the module is to first remove the passenger side front wheel and the inner wheel arch plastic liner, then the washer bottle can be unbolted and moved out of the way giving access to the six torx screws. Remember you can still drive the car with the module removed - you will have conventional braking but with no ABS function and the light will remain on untill the remanufactured module is refitted.
