199000774 - F020 ABS WORKING IRREGULARLY

When the brakes are operated briskly and suddenly (emergency braking) the ABS does not work properly and, as a result, one or more of the wheels is partly locked
Results of the tests
0PRELIMINARY CHECKSAll OKProblems encounteredOperation
Turn the ignition ON and check that the "ABS failure" warning light comes on for around 4 seconds and then goes outMove on to Step 1The "ABS failure" warning light comes on and stays onProceed as instructed,    See table K060 ABS FAILURE WARNING LIGHT ON
1CHECK USING DIAGNOSTIC EQUIPMENTAll OKProblems encounteredOperation
Connect the Examiner diagnostic equipment to the diagnostic socket and check:- that there are no faults in the ABS control unit;- the plausibility of all the parametersMove on to Step 21. Error detected in the control unit2. No communication with the control unit3. Fault detected in one of the front sensors4. Fault detected in one of the rear sensors5. Fault detected in one of the front wheel hubs6. Fault detected in one of the rear wheel hubs.1. Continue following the instructions for the diagnostic equipment2. Restore connection between the ABS control unit and the diagnostic connector see    See E7020 ABS 3. Replace the sensor    Op. 3340A30 RPM SENSOR (ONE) FOR ONE FRONT WHEEL, LEFT OR RIGHT - R.R. 4. Replace the sensor    Op. 3340A34 LEFT OR RIGHT REAR WHEEL RPM SENSOR (ONE) - R.R. 5. Replace the wheel hub    Op. 4450C10 FRONT STEERING KNUCKLE (ONE), L/H OR R/H COMPLETE WITH WHEEL HUB - R+R WITH WHEEL REMOVED - CHECK WHEEL GEOMETRY SEPARATELY 6. Replace the wheel hub    Op. 4450D10 HUB FOR ONE REAR WHEEL, L/H OR R/H - R+R WITH WHEEL REMOVED - CHECK WHEEL GEOMETRY SEPARATELY
2ACTIVE DIAGNOSIS WITH DIAGNOSTIC EQUIPMENTAll OKProblems encounteredOperation
Keeping the diagnostic equipment connected carry out the active diagnosis of:- pump motor;- solenoid valvesMove on to Step 3Fault detected in one of the solenoid valvesReplace the electrohydraulic unit - ABS electronic control unit    Op. 3340A12 ABS HYDRAULIC AND ELECTRONIC CONTROL UNIT - R.R.
3BRAKE CALIPER CHECKAll OKProblems encounteredOperation
Check the sliding of the brake caliper control pistonsMove on to Step 41. Front caliper pistons seized2. Rear caliper pistons seized1. Replace the front brake calipers    Op. 3310A30 FRONT BRAKE CALIPER (ONE) - R.R 2. Replace the rear brake calipers    Op. 3310B36 REAR BRAKE CALIPER (ONE), LEFT OR RIGHT - R.R
4CHECK ON PIPES / HOSES AND BLEED BRAKESAll OKProblems encounteredOperation
Visually inspect that there are no bends or constrictions in the brake pipes, bleed the system and check that the fluid comes out evenly from the bleed screwsEnd of diagnosisBends or constrictions present, the fluid does not come out evenlyReplace the section of pipe affected by the problem