2888355 - F20 ABS WORKING IRREGULARLY

When the brakes are operated vigorously and suddenly ("panic" braking), the ABS does not work properly, so one or more wheels lock(s).
Results of the tests
0PRELIMINARY CHECKSAll OKProblems metOperation
Turn the ignition on and check that the "ABS fault" warning light comes on for about 4 seconds, and then goes out.Continue to Step 1The "ABS fault" warning light comes on and stays on See table   K60  ABS FAILURE WARNING LIGHT ON
1CHECK WITH DIAGNOSTIC EQUIPMENTAll OKProblems metOperation
Connect the diagnostic equipment (Examiner or other instruments) to the diagnostic socket

Check:

  • that there are no faults in the ABS control unit
  • plausibility of all the parameters
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 unitRestore the connection between the ABS control unit and the diagnostic connector ( See   E7020  ABS )
Fault detected in a front sensorReplace the sensor Op.   3340A30 
Fault detected in a rear sensorReplace the sensor Op.   3340A34 
Fault detected in a front wheel hub Replace the wheel hub Op.   4450C10 
Fault detected in a rear wheel hub Replace the wheel hub Op.   4450D10 
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 
3CHECKING CORRECT OPERATIONAll OKProblems metOperation
Check that the fault is no longer presentEnd of diagnosisFault persistsSearch for the fault starting from another symptom'