Circuit Description
The electronic brake control module (EBCM) controls the operation of the amber ABS warning lamp by means of a lamp driver module contained within the cluster.
Battery voltage is supplied to the instrument panel (I/P) cluster terminal B9, and the electronic brake control module terminal 4 when the ignition switch is turned ON. EBCM terminals 9 and 25 are hot at all times.
The default state is for the lamp driver module to turn ON the amber ABS warning lamp, by supplying a ground path through the lamp driver module.
When the EBCM commands the ABS lamp OFF, the EBCM will ground the ABS warning lamp control circuit. This causes the lamp driver module to open the path to ground for the bulb.
When the ignition switch is turned to the ON position, the EBCM turns ON the ABS warning lamp for 3 seconds for a bulb check.
Whenever a malfunction is detected within the ABS system, the EBCM turns ON the ABS warning lamp, notifying the driver that the ABS needs to be serviced.
Diagnostic Aids
Typical causes of the ABS warning lamp ON with no DTCs set:
| • | Grounded circuit between the cluster and the EBCM |
| • | Faulty cluster/lamp driver module |
| • | Faulty EBCM |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: Antilock Brake System Schematics Connector End View Reference: Antilock Brake System Connector End Views | ||||
1 | Did you perform a Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
2 |
Did the amber ABS lamp turn OFF? | -- | Go to Step 3 | Go to Step 4 |
3 | Replace the EBCM. Refer to Brake Pressure Modulator Valve Assembly Replacement . Did you complete the replacement? | -- | System OK | -- |
4 |
Was the resistance within the specific value? | OL (open circuit) | Go to Step 6 | Go to Step 5 |
5 | Find and repair the short to ground between the cluster harness and the LDM harness. Did you find and correct the condition? | -- | System OK | -- |
6 |
Was the resistance measured less than the specific value? | 2 Ω | Go to Step 8 | Go to Step 7 |
7 | Repair the open or high resistance between the LDM and the EBCM. Did you find and correct the condition? | -- | System OK | -- |
8 | Replace the LDM. Did you complete the replacement? | -- | System OK | -- |
9 | Replace the cluster assembly. Refer to Instrument Cluster Replacement . Did you complete the replacement? | -- | System OK | -- |
