B76531.0
ELECTRONICALLY CONTROLLED HYDRAULIC SYSTEMS
Fault finding - Introduction38
ABS BOSCH
5.3
CONDITIONS FOR APPLICATION FOR THE TESTS DEFINED IN THIS FAULT FINDING
The tests described in this fault finding are only to be applied when the wording of the fault corresponds
exactly to the display on the XR25 kit.
If a fault is dealt with because there is a flashing bargraph, the conditions for confirming the existence of an
actual fault (and the need to apply the fault finding ) can be found in the "Notes" or at the beginning of the
bargraph interpretation.
If a bargraph is only interpreted when it is permanently illuminated, the application of the recommended
tests in the fault finding when the bargraph is flashing will not allow you to determine the origin of the
memorisation of this fault. In this case, only a test of the wiring and the connections of the component in
question must be carried out (the fault is simply memorised as it was not present at the time of testing).
NOTE : The ignition must have been switched off before the XR25 kit is used.
INDISPENSABLE TOOLING REQUIRED FOR OPERATIONS ON THE ABS SYSTEM
- XR25 kit.
- XR25 cassette n° 16 minimum.
Reminders :When there is intermittent fault memorisation, the ABS warning light will illuminate the next
time the vehicle is used until the car reaches 7.5mph (12 km/h). When the fault is memorised, a
counter relating to the fault is set at 40 . This value is reduced by one each time the ignition is
turned on if the fault is not present when the vehicle exceeds 7.5mph (12 km/h). When the
reading on the counter is equal to 1, it remains at 1 and the fault is not erased.
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B76531.0
ELECTRONICALLY CONTROLLED HYDRAULIC SYSTEMS
Fault finding - Interpretation of XR25 bargraphs
38
ABS BOSCH
5.3
After replacing the computer, carry out another XR25 test.AFTER REPAIR
Bargraph 1 left hand side illuminated
Power supply/computer
1
None.
NOTES
Fiche n° 53
Erase the computer memory, exit the fault finding (G13*) and switch off the ignition.
Carry out a new XR25 test. If the "power supply / computer" fault persists, replace the ABS computer.
Check the condition and position of the 60A ABS fuse in the engine connection unit (white mounting).
Ensure continuity between this fuse and tracks 17 and 18 of the computer connector (presence of positive
before ignition feed on both tracks). Check the tightness and condition of the battery terminals.
Check the connections on the 31 track connector of the ABS computer.
Check the ABS earths (above the hydraulic assembly) and visually check all the ABS wiring.
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B76531.0
ELECTRONICALLY CONTROLLED HYDRAULIC SYSTEMS
Fault finding - Interpretation of XR25 bargraphs
38
ABS BOSCH
5.3
Erase computer memory(GO**).
Carry out a road test followed by a check with the XR25 kit.AFTER REPAIR
Bargraph 6 left hand side illuminated
Front left wheel sensor circuit
6
None.
NOTES
Fiche n° 53
If the resistance is correct, check and ensure the continuity of the connection between the sensor
connector and the computer connector:
- between one track of the sensor connector and track 7 of the computer connector,
- between the other track of the sensor connector and track 6 of the computer connector.
Also check the insulation between these connections.
Carry out a visual inspection of the sensor wiring and check the quality of the connection on the 31 track
computer connector.
If all the checks are correct, reconnect the computer and the wheel speed sensor then erase the computer
memory.
Exit fault finding mode(G13*) and switch off the ignition.
Switch the ignition on and replace the sensor if the fault reappears.
If the fault reappears after replacing the sensor, replace the computer.
Check the connection and condition of the sensor connections.
If the connector is correct, check the resistance of the sensor at its connector..
Replace the sensor if its resistance is not approximately 1.6 Kohms (1,6 Kohms ± 320 ohms).
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B76531.0
ELECTRONICALLY CONTROLLED HYDRAULIC SYSTEMS
Fault finding - Interpretation of XR25 bargraphs
38
ABS BOSCH
5.3
Erase computer memory(GO**).
Carry out a road test followed by a check with the XR25 kit.AFTER REPAIR
Bargraph 6 Right hand side illuminated
Front right wheel sensor circuit
6
None.
NOTES
Fiche n° 53
If the resistance is correct , check and ensure the continuity of the connections between the sensor
connector and the computer connector :
- between one track of the sensor connector and track 3 of the computer connector,
- between the other track of the sensor connector and track 5 of the computer connector.
Also check the insulation between these connections.
Carry out a visual inspection of the sensor wiring and check the quality of the connections on the 31
track computer connector.
If all the checks are correct, reconnect the computer and the wheel speed sensor, then erase the
computer memory.
Exit the fault finding mode(G13*) and switch off the ignition.
Switch the ignition on and replace the sensor if the fault reappears .
If the fault reappears after replacing the sensor, replace the computer.
Check the connection and condition of the sensor connections.
If the connector is correct, check the resistance of the sensor at its connector.
Replace the sensor if its resistance is not approximately 1.6 Kohms (1.6 Kohms ± 320 ohms).
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B76531.0
ELECTRONICALLY CONTROLLED HYDRAULIC SYSTEMS
Fault finding - Interpretation of XR25 bargraphs
38
ABS BOSCH
5.3
Erase computer memory(GO**).
Carry out a road test followed by a check with the XR25 kit.AFTER REPAIR
Bargraph 7 left hand side illuminated
Rear left wheel sensor circuit
7
None.
NOTES
Fiche n° 53
If all checks are correct, reconnect the computer and wheel speed sensor, then erase the computer
memory.
Exit fault finding mode(G13*) and switch off the ignition.
Switch on the ignition and replace the sensor if the fault reappears.
If the fault reappears after replacing the sensor, replace the computer.
Check the connection and condition of the sensor connections.
Check the connections at the intermediate connection under the body (R101).
If the connector is correct, check the resistance of the sensor at its connector. Replace the sensor if the
resistance is not approximately 1.6 Kohms (1.6 Kohms ± 320 ohms).
If the resistance is correct, check and ensure the continuity of the connections between the sensor
connector and the computer connector :
- between one track of the sensor connector and track 8 of the computer connector (via track B of the
connector under the body R101),
- between the other track of the sensor connector and track 9 of the computer connector (via track A of
the connector under the body R101).
Also check the insulation between these connections.
Carry out a visual inspection of the sensor wiring and check the quality of the connections on the 31 track
computer connector.
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B76531.0
ELECTRONICALLY CONTROLLED HYDRAULIC SYSTEMS
Fault finding - Interpretation of XR25 bargraphs
38
ABS BOSCH
5.3
Erase computer memory(GO**).
Carry out a road test followed by a check with the XR25 kit.AFTER REPAIR
Bargraph 7 Right hand side illuminated
Rear right wheel sensor circuit
7
None.
NOTES
Fiche n° 53
If all checks are correct, reconnect the computer and the wheel speed sensor, then erase the computer
memory.
Exit fault finding mode(G13*) and switch off the ignition.
Switch on the ignition and replace the sensor if the fault reappears.
If the fault reappears after replacing the sensor, replace the computer.
Check the connection and condition of the sensor connections.
Check the connections at the intermediate connector under the body (R101).
If the connector is correct , check the resistance of the sensor at its connector.
Replace the sensor if its resistance is not approximately 1.6 Kohms (1.6 Kohms ± 320 ohms).
If the resistance is correct, check and ensure the continuity of the connections between the sensor
connector and the computer connector :
- between one track of the sensor connector and track 1 of the computer connector (via track D of the
connector under the body R101),
-between the other track of the sensor connector and track 2 of the computer connector (via track C of
the connector under the body R101).
Also check the insulation between these connections.
Carry out a visual inspection of sensor wiring and check the quality of the connections on the 31 track
computer connector.
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B76531.0
ELECTRONICALLY CONTROLLED HYDRAULIC SYSTEMS
Fault finding - Interpretation of XR25 bargraphs
38
ABS BOSCH
5.3
Erase computer memory(GO**).
Carry out a road test followed by a check with the XR25 kit.AFTER REPAIR
Bargraph 8 right or left hand side flashing
Front right or front left wheel sensor signal
Even if they are present at time of testing, these faults will always be declared by
BG 8 flashing on the left or right hand side.
To confirm their presence and therefore the need to apply the fault finding be-
low, carry out a road test. The fault is present if the bargraph illuminates during
the test.
If bargraphs 6 and 8 left hand side are both illuminated, deal with bargraph 6
first.
If bargraphs 6 and 8 right hand side are both illuminated, deal with bargraph 6
first.
NOTES
Fiche n° 53 8
Check the quality of the wheel speed sensor mounting (its position and that it is tightened to
recommended torque).Check the sensor / target air gap over one wheel revolution : 0.13 mm < air
gap< 1.96 mm. Check conformity of the target (condition, number of
teeth=26)
Carry out a visual inspection of the sensor wiring and check the quality of the connections on the 31 track
computer connector.
If all checks are correct, reconnect the computer and the wheel speed sensor, then erase the computer
memory.
Leave fault finding mode(G13*) and carry out a road test. Replace the sensor if the fault reappears.
If the fault reappears after replacing the sensor, it may be caused by an operating fault on a solenoid
valve and it is therefore necessary to carry out the hydraulic check of the solenoid valves with the XR25 kit
with command G03* or G04* (consult the section "Aid"). If the ten unlocking/locking cycles do not occur
on one of the wheels, replace the hydraulic assembly.
If the hydraulic assembly is not at fault, replace the computer.
Check the connection and condition of the sensor connections.
If the connector is correct , check the resistance of the sensor at its connector.
Replace the sensor if its resistance is not approximately 1.6 Kohms (1.6 Kohms ± 320 ohms).
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B76531.0
ELECTRONICALLY CONTROLLED HYDRAULIC SYSTEMS
Fault finding - Interpretation of XR25 bargraphs
38
ABS BOSCH
5.3
Erase computer memory(GO**).
Carry out a road test followed by a check with the XR25 kit.AFTER REPAIR
Bargraph 9 right or left hand side flashing
Signals to rear right or rear left wheel sensor
Even if present at time of test, these faults will always be declared by BG9 flas-
hing on the left or right hand side.
To confirm their presence and therefore the need to apply the fault finding be-
low, carry out a road test.The fault is present if the bargraph illuminates during
the test.
If bargraphs 7 and 9 left hand side are both illuminated, deal with bargraph 7
first.
If bargraphs 7 and 9 right hand side are both illuminated, deal with bargraph 7
first.
NOTES
Fiche n° 53 9
Check the quality of the wheel speed sensor mounting (position and torque tightening).
Check the connection and condition of the sensor connections.
Check the connections at the intermediate connector under the body R101.
If the connector is correct , check the resistance of the sensor at its connector.
Replace the sensor if its resistance is not approximately 1.6 Kohms (1.6 Kohms ± 320 ohms).
Carry out a visual inspection of the sensor wiring and check the quality of the connections on the 31 track
computer connector.
If all checks are correct, reconnect the computer and the wheel speed sensor, then erase the computer
memory. Leave fault finding mode(G13*) and carry out a road test.
If the fault reappears, check the sensor/target air gap over one wheel rotation :
0.03 mm < air gap< 2.4 mm (test only possible on vehicle with 4 bar rear axle).
Check conformity of the target:condition, number of teeth = 26.
If the fault reappears after replacing sensor, it could be caused by a solenoid valve operating fault. It is
therefore necessary to carry out a hydraulic test of the solenoid valves with the XR25 kit with command
G05* or G06* (consult section"Aid"). If the ten unlocking/locking cycles do not occur on one of the
wheels, replace the hydraulic assembly.
If the hydraulic assembly is not at fault, replace the computer.
If all checks are correct, leave fault finding mode(G13*) and carry out a road test.
Replace the sensor if the fault reappears.
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