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:
| • | Short to ground in CKT 867 |
| • | Open or high resistance in CKT 1899 |
| • | Open or high resistance in CKT 393 |
| • | The ABS indicator lamp relay is faulty |
| • | The EBCM is faulty |
Diagnostic Aids
If the ABS indicator lamp is on always with no DTCs set (never turns off with the vehicle started or with the ignition switch in the RUN position), there is a short to ground in CKT 867 between the instrument cluster and the EBCM, or there is a fault in the ABS indicator lamp relay circuit.
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 off the ABS indicator lamp.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Diagnostic System Check performed? | -- | Go to Step 2 | Go to A Diagnostic System Check |
Does the ABS indicator lamp turn off? | -- | Go to Step 5 | Go to Step 3 | |
Does the ABS indicator lamp turn off? | -- | Go to Step 4 | Go to Step 6 | |
4 | Using a J 39200 , measure the voltage between the ABS indicator relay harness connector terminal 85 and ground. Is the voltage measured equal to or greater than the specified value? | 10V | Go to Step 4 | Go to Step 7 |
5 | Using a J 39200 , measure the resistance between the relay center harness connector terminal 86 and the EBCM harness connector terminal 2. Is the resistance within the specified range? | 0-2ohms | Go to Step 9 | Go to Step 8 |
6 |
Inspect CKT 1899 or CKT 395 for damage that could result in an open circuit. Repair damage if evident. Replace the terminals if poor contact or corrosion exists. Is the ABS indicator lamp on constantly? | -- | Go to Step 7 | Refer to Diagnostic Aids |
7 | Repair the short to ground in CKT 392 or CKT 38. Refer to Wiring Repairs . Is the repair complete? | -- | Go to A Diagnostic System Check | -- |
8 | Repair the open or the high resistance in CKT 393, CKT 145 or a damaged circuit breaker #9. Refer to Wiring Repairs . Is the repair complete? | -- | Go to A Diagnostic System Check | -- |
9 | Repair an open in CKT 395 or CKT 1899. Refer to Wiring Repairs . Is the repair complete? | -- | Go to A Diagnostic System Check | -- |
10 | Replace the ABS indicator relay. Is the repair complete? | -- | Go to A Diagnostic System Check | -- |
