Component Tests and General Diagnostics
CAUTION:- USE ONLY a multi-meter with compatible male blades to match female spring sockets. Damaged female sockets will necessitate unnecessary component replacement.
- To avoid damage to the contacts of the 35 way connector, the manufacturers recommend the use of the adaptor plug.
- When this adaptor is fully engaged with the 35 way connector, multimeter probes can be inserted into the numbered contacts on the face of the adaptor. The adaptor plug is supplied as a spares item from Land Rover. If the adaptor is not available, carefully back-probe the connector.
- Ensure the multi-meter is correctly set to volts or ohms, dependant on which test is being carried out. Ensure ignition is switched ON or OFF as test requires.
SETUP
1. Disconnect 35 way connector from ECU.
2. Connect adaptor plug. Commence check at appropriate pin on 35 way on wiring harness.
3. Check harness wires for continuity, check fuses and relays.
4. Test related components.
5. If intermittent contact is suspected, attempt to locate the fault by flexing the harness and cables or moving contacts.
The following tests are intended as a guide to locating a fault within a circuit. Refer to the ABS circuit diagram for full circuit information.
Key to symbols
NOTE: If the correct reading is obtained at the component connector and NOT at the 35 way connector, the harness is at fault.
TEST PROCEDURE
1. Check battery voltage.
Results/Checks
Correct result: 10V
Incorrect result: Check fuse AB11, wiring from ignition switch and ground.
2a. Check valve relay AB14.
Correct result: 0 Volts If voltage reading obtained check relay.
2b. Check valve relay power supply.
Correct result: 10 Volts
Incorrect result: Check wiring to relay, pins 8, 9 and 27 to ground.
TEST PROCEDURE
3a. Check front left wheel speed sensor resistance.
Results/Checks
Correct result: 1.5-2 kOhm
Incorrect result at sensor plug: Fit new sensor.
3b. Check front left wheel speed sensor insulation.
Correct result: 1OO kOhm
Incorrect result at sensor plug: Fit new sensor.
4a. Check front right wheel speed sensor resistance.
Correct result: 1.5-2 kOhm
Incorrect result at sensor plug: Fit new sensor.
TEST PROCEDURE
4b. Check front right wheel speed sensor insulation.
Results/Checks
Correct result: 100 kOhm
Incorrect result at sensor plug: Fit new sensor.
5a. Check rear left wheel speed sensor resistance.
Correct result: 1.5-2 kOhm
Incorrect result at sensor plug: Fit new sensor.
5b. Check rear left wheel speed sensor insulation.
Correct result: 100 kOhm
Incorrect result at sensor plug: Fit new sensor.
TEST PROCEDURE
6a. Check rear right wheel speed sensor resistance.
Results/Checks
Correct result: 1.5-2 kOhm
Incorrect result at sensor plug: Fit new sensor.
6b. Check rear right wheel speed sensor insulation.
Correct result: 100 kOhm
Incorrect result at sensor plug: Fit new sensor.
7a. Check isolation valve outlet.
(1) Remove booster harness plug, carry out check at booster.
(2) Refit booster harness plug, carry out check at 35 way.
Correct result: 5-7 Ohm
Incorrect result at booster: Fit new booster.
TEST PROCEDURE
7a. Check isolation valve, inlet.
(1) Remove booster harness plug, carry out check at booster.
(2) Refit booster harness plug, carry out check at 35 way. Incorrect result at booster: Fit new booster.
Results/Checks
Correct result: 5-7 Ohm
8a. Check ABS solenoid valve front left, outlet.
(1) Remove booster harness plug, carry out check at booster.
(2) Refit booster harness plug, carry out check at 35 way.
Correct result: 2.5-4.5 Ohm
Incorrect result at booster: Fit new booster.
TEST PROCEDURE
8b. Check ABS solenoid valve front left, inlet.
(1) Remove booster harness plug, carry out check at booster.
(2) Refit booster harness plug, carry out check at 35 way.
Results/Checks
Correct result: 5-7 Ohm
Incorrect result at booster: Fit new booster.
9a. Check ABS solenoid valve front right, outlet.
(1) Remove booster harness plug,carry out check at booster.
(2) Refit booster harness plug, carry out check at 35 way.
Correct result: 2.5-4.5 Ohm
Incorrect result at booster: Fit new booster.
9b. Check ABS solenoid valve front right, inlet.
(1) Remove booster harness plug,carry out check at booster.
(2) Refit booster harness plug, carry out check at 35 way.
Correct result: 5-7 Ohm
Incorrect result at booster: Fit new booster.
TEST PROCEDURE
10a. Check ABS solenoid valve rear left, outlet.
(1) Remove booster harness plug,carry out check at booster.
(2) Refit booster harness plug, carry out check at 35 way.
Results/Checks
Correct result: 2.5-4.5 Ohm
Incorrect result at booster: Fit new booster.
10b. Check ABS solenoid valve rear left, inlet.
(1) Remove booster harness plug,carry, out check at booster.
(2) Refit booster hamess plug, carry out check at 35 way.
Correct result: 5-7 Ohm
Incorrect result at booster: Fit new booster.
TEST PROCEDURE
11a. Check ABS solenoid valve rear right, outlet.
(1) Remove booster harness plug, carry out check at booster.
(2) Refit booster harness plug, carry out check at 35 way.
Results/Checks
Correct result: 2.5-4.5 Ohm
Incorrect result at booster: Fit new booster.
11b. Check ABS solenoid valve rear right, inlet.
(1) Remove booster harness plug, carry out check at booster.
(2) Refit booster harness plug, carry out check at 35 way.
Correct result: 5-7 Ohm
Incorrect result at booster: Fit new booster.
12a. Check brake light switch - pedal down.
Correct result: 10 Volts
This contact must operate first and switch the brake lights.
Incorrect reading: Fit new brake light switch and recheck. Check cable if fault persists.
TEST PROCEDURE
12. Check brake light switch - pedal down.
Results/Checks
Correct result: 10 Volts
Incorrect reading: Fit new brake light switch and recheck. Check cable if fault persists.