Circuit Description
The amber ABS indicator lamp operates in two modes; normal and backup. In the normal mode, ignition voltage is supplied to the ABS indicator light bulb in the instrument cluster through the IGN SW fuse. The indicator is normally on unless the EBCM switches the indicator off, by energizing the ABS indicator lamp relay and opening the circuit. If the EBCM senses that a fault has occurred, it will set a DTC and light the ABS indicator lamp by grounding the ABS indicator lamp circuit. In the backup mode, the ABS indicator lamp relay circuit (normally closed) will ensure that the ABS indicator lamp is illuminated if the 24-way connector is disconnected or poorly seated, or if the EBCM has failed during normal operation. If either of these fault conditions occur, the ABS indicator lamp will be illuminated. if the following conditions exist:
| • | Open or high resistance in CKT 867 |
| • | The EBCM is faulty |
Diagnostic Aids
If the ABS indicator lamp is off always with no DTCs set (never turns on at bulb check, with the vehicle started or with the ignition switch in the RUN position), an open or high resistance in the lamp circuit is present between the instrument panel and the EBCM. Also check for an open instrument panel fuse or an open bulb.
Test Description
The numbers below refer to the steps in the diagnostic table:
-
This step checks for normal operation of the ABS indicator lamp.
-
This step manually (with fused jumper) turns on the ABS indicator lamp by bypassing the ABS indicator relay.
-
This step checks for a short to ground in CKT 1899.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Diagnostic System Check performed? | -- | Go to Step 2 | |
Does the ABS indicator lamp turn on? | -- | Go to Step 3 | Go to Step 4 | |
Using a J 39200 , measure the resistance between the relay center harness connector terminal 87A and ground. Is the resistance within the specified range? | 0-2 ohms | Go to Step 9 | Go to Step 7 | |
4 | Inspect the jumper fuse wire. Is the fuse open? | -- | Go to Step 6 | Go to Step 5 |
Is the resistance within the specified range? | 0-2 ohms | Go to Instrument Panel for ABS indicator light repair. | Go to Step 8 | |
6 | Repair a short to voltage in CKT 392, CKT 38, CKT 391 or CKT 867. Refer to Wiring Repairs . Is the repair complete? | -- | -- | |
7 | Repair an open in CKT 394. Refer to Wiring Repairs . Is the repair complete? | -- | -- | |
8 | Repair an open in CKT 392 or CKT 38. Refer to Wiring Repairs . Is the repair complete? | -- | -- | |
9 | Repair the open or the high resistance in CKT 867. Refer to Wiring Repairs . Is the repair complete? | -- | -- |
