Code 42251 or 22251

Cause Of Fault
The fault may be caused by the following:
- Break in continuity/short-circuit in any of the + 30 power supply circuits via the main relay, pins 3 and 33
- Break in continuity/short-circuit to + 12 V in the control circuit, pin 34
Activated = 0 Volts
Non-activated = 12 Volts

NOTE:
- The following faults do not trigger any trouble code and no contact can be established between the ISAT and the system.
- The warning light is lit.

- Break in continuity in the circuit for + 54 supply to pin 53
- Short-circuit to earth in the circuit for + 54 supply to pin 53 (Antilock Brake System (ABS) 10 amp fuse has blown)

Symptom
The ANTI LOCK light is lit

Action





NOTE:
- If there is any other trouble code in addition to trouble code 42251, this must be dealt with first.
- All measurements are to be carried out using the breakout box (part No. 86 11 006) connected between the connector and the Electronic Control Unit (ECU) (see Fault Tracing (Connecting The BOB)).

1. With the ignition switch in the Drive position, check that there is battery voltage at pins 3 and 33.
- If there is no voltage at either pin, check the ABS 30 amp fuse for the + 30 supply in the main fuse box on the bulkhead and the red wire from the fuse to the main relay and to the distribution block on the battery tray.
2. If there is no voltage at any of the pins, check the wire from the ECU to the main relay from the pin concerned.
3. With 0 Volts on pin 34 and no voltage at pins 3 and 33, check that the 10 amp fuse (ABS) is intact.
a. If the fuse is intact, check the power supply to pin 53.
If there is no voltage, continue from step e).
b. If there is voltage at pin 53, check the green wire between pin 85 of the system relay and pin 34 of the ECU.
c. Check that there is voltage at pin 86 of the system relay.
If not, continue from f).
d. If there is voltage, try a new system relay.
e. If there is no voltage at pin 53 either, check the red and white wire as far as the fuse.
Also check that power is supplied from pin 54 of the ignition switch in the grey and white wire as far as the supply side of the ABS fuse.
f. Check the red and white wire between 86 on the system relay via the pump relay to the 10 A fuse.
4. If there is battery voltage on pin 34 but no voltage on pins 3 and 33, the control circuit is correct but the ECU has not grounded the circuit due to a different fault in the ABS system.