Brake System Indicator Circuit Troubleshooting

Brake system indicator does not come on


1.Turn the ignition switch ON (II).

Does the ABS indicator come on?


YES - Go to 2.


NO - Repair open in the indicator power source circuit:n

  • Blown No. 3 (7.5 A) fuse in the under-dash fuse/relay box.
  • Open in the wire between the No. 3 (7.5 A) fuse and the gauge assembly.
  • Open circuit inside the fuse box.

2.Turn the ignition switch OFF.

3.Disconnect the negative cable from the battery.

4.Disconnect the ABS control unit 25P connector.

5.Reconnect the battery cable.

6.Connect ABS control unit 25P connector terminal No. 16 and body ground with a jumper wire.

7.Turn the ignitions switch ON (II).

 

Does the brake system indicator come on?


YES - Check for loose terminals in the ABS control unit 25P connector. If necessary substitute a known-good  ABS modulator-control unit, and recheck.n


NO - Go to 8.

8.Apply parking brake.

Does the brake system indicator come on?


YES - The system is OK at this time.n


NO - Go to 9.


9.Check the parking brake switch.

Is the switch OK?


YES - Go to 10.


NO - Replace the parking brake switch.n


10.Remove the gauge assembly.

11.Connect the gauge assembly connector C (30P) terminal No. 7 and body ground with a jumper.

12.Turn the ignition switch ON (II).

 

Does the brake system indicator come on?


YES - Repair open in the wire between the parking brake switch and the gauge assembly.n


NO - Replace the gauge assembly.n

Brake system indicator does not go off


1.Release the parking brake.

Does the brake system indicator go off?


YES - The system is OK at this time.n


NO - Go to 2.


2.Check the parking brake switch.

Is the switch OK?


YES - Go to 3.


NO - Refill the  brake fluid level switch.n


3.Check the brake fluid level.

Is the level OK?


YES - Go to 4.


NO - Replace the parking brake switch.n


4.Check the brake fluid level switch.

Is the switch OK?


YES - Go to 5.


NO - Replace the  brake fluid level switch.n


5.Turn the ignition switch OFF.

6.Disconnect the negative cable from the battery.

7.Disconnect the ABS control unit 25P connector.

8.Reconnect the battery cable.

9.Turn the ignition switch ON (II).

Does the brake system indicator go off?


YES - Replace the  ABS modulator-control unit.n


NO - Go to 10.


10.Turn the ignition switch OFF.

11.Turn the ignition switch OFF.

12.Disconnect the negative cable from the battery.

13.Remove the gauge assembly.

14.Disconnect the gauge assembly connector C (30P).

15.Check for continuity between the gauge assembly connector C (30P) terminals No. 6 and body ground.

 

Is there continuity?


YES - Repair short to body ground in the wire between the gauge assembly and the ABS modulator-control unit.n


NO - Repair short to body ground in the wire between the brake system indicator and the parking brake switch or between the brake system indicator and the  brake fluid level switch.n