2888352 - F02 REAR WHEELS LOCK WHILST BRAKING

When the brakes are operated, the distribution between front and rear wheels is not correct: at worst, the rear wheels may lock and the car may skid
Results of the tests
0PRELIMINARY CHECKSAll OKProblems metOperation
Carry out a preliminary check to see whether the ABS and handbrake warning lights come on simultaneously during starting and then go out.Continue to Step 1After starting, the two warning lights remain on See table   K62  ABS AND HANDBRAKE WARNING LIGHTS BOTH ON
1CHECK WITH DIAGNOSTIC EQUIPMENTAll OKProblems metOperation
Connect the diagnostic equipment (Examiner or other instruments) to the diagnostic socketCheck that there are no faults in the ABS control unit.Continue to Step 2An error is detected in the control unitContinue according to the instructions for the diagnostic equipment
Lack of dialogue with the control unit

Restore:

  • the connection between the ABS control unit and the diagnostic connector
  • the ABS control unit supply
See   E7020  ABS
2ACTIVE DIAGNOSIS WITH DIAGNOSTIC EQUIPMENTAll OKProblems metOperation

Using the diagnostic equipment (Examiner or other instruments) carry out the active diagnosis of:

  • pump motor
  • solenoids
Continue to Step 3Fault detected in one solenoidReplace electrohydraulic unit-electronic control unit Op.   3340A12 
3CHECK BRAKE PIPES/HOSES AND BLEEDINGAll OKProblems metOperation
Visually check that there are no kinks or restrictions in the brake pipes, bleed the system Op.   3330A18  and check that fluid emerges from the bleed screws as normalContinue to Step 4There are kinks or restrictions, fluid does not come out normallyReplace the section of pipe affected by the fault (see Assembly 3340B)
4CHECKING CORRECT OPERATIONAll OKProblems metOperation
Check that the fault is no longer presentEnd of diagnosisFault persistsSearch for the fault starting from another symptom'
When the brakes are operated, the distribution between front and rear wheels is not correct: at worst, the rear wheels may lock and the car may skid
Results of the tests
1LOAD PROPORTIONING VALVE CHECKAll OKProblems metOperation
Check that the rear load proportioning valve is correctly calibrated Op.   3330C62  Continue to Step 2Load proportioning valve incorrectly calibratedRestore the calibration Op.   3330C62 
Load proportioning valve faultyReplace the load proportioning valve Op.   3330C60 
2CHECK BRAKE PIPES/HOSES AND BLEEDINGAll OKProblems metOperation
Visually check that there are no kinks or restrictions in the brake pipes, bleed the system Op.   3330A18  and check that fluid emerges from the bleed screws as normalContinue to Step 3There are kinks or restrictions, fluid does not come out normallyReplace the section of pipe which is faulty (see Assembly 3330E)
3CHECKING CORRECT OPERATIONAll OKProblems metOperation
Check that the fault is no longer presentEnd of diagnosisFault persistsSearch for the fault starting from another symptom'