Circuit Description
The Electronic Brake Control Module (EBCM) controls the operation of the amber ABS indicator lamp by means of a lamp driver relay.
The amber ABS indicator lamp is connected to the IG-COIL METER fuse through CKT 8B01. This circuit is hot in ON and START ignition switch positions.
When the lamp driver relay is in the OFF state (CKT 9U01 is open), the lamp driver relay grounds the amber ABS indicator lamp through CKT 6B01. This turns ON the amber ABS warning indicator.
When the EBCM commands OFF the ABS warning indicator, the EBCM turns ON the lamp driver relay by grounding CKT 9U01. This causes the lamp driver relay to open the path to ground in CKT 6B01, turning OFF the amber ABS warning indicator.
When the ignition switch is turned to the ON position, the EBCM turns ON the ABS indicator for 3 seconds for a bulb check. Whenever a malfunction is detected within the ABS system, the EBCM tuns ON the ABS indicator, notifying the driver that ABS needs to be serviced. If the EBCM commands the red BRAKE warning indicator ON due to an ABS malfunction that may degrade base braking operation and cannot do so, the ABS indicator will flash to indicate the serious nature of the problem.
Diagnostic Aids
Thoroughly inspect any circuitry that may cause the intermittent complaint for the following conditions:
| • | Backed out terminals |
| • | Improper mating |
| • | Broken locks |
| • | Improperly formed or damaged terminals |
| • | Poor terminal-to-wiring connections |
| • | Physical damage to the wiring harness |
| • | Short to ground between the lamp driver relay and the amber ABS indicator lamp (CKT 6B01) |
| • | Open circuit or high resistance between the EBCM and the lamp driver relay (CKT 9U01) |
| • | Open coil or constantly closed contacts of the lamp driver relay |
Important: Zero the J 39200 test leads before making any resistance measurements. Refer to the J 39200 user's manual.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Diagnostic System Check performed? | -- | Go to Diagnostic System Check | |
2 |
Do not start the engine. Did the amber ABS warning indicator toggle ON and OFF? | -- | ||
3 |
Is the amber ABS warning indicator ON? | -- | ||
4 | Check CKT 6B01 for a short to ground and repair as necessary. Was there a problem found and corrected? | -- | ||
5 | Repair the Instrument Panel Cluster. Refer to Instrument Cluster, Cell 81, in Electrical Diagnosis. Is the repair complete? | -- | -- | |
6 |
Did the test light turn ON? | -- | ||
7 |
Did the test light toggle ON and OFF? | -- | ||
8 | Inspect for proper terminal contact at the lamp driver relay. Was there a problem found and corrected? | -- | ||
9 | Replace the lamp driver relay. Is the repair complete? | -- | -- | |
10 | Check CKT 9U01 for an open or high resistance condition. Was there a problem found and corrected? | -- | ||
11 | Replace the EBCM. Refer to Electronic Brake Control Module Replacement . Is the repair complete? | -- | -- | |
12 | Check CKT 8B01 for an open or high resistance condition. Was there a problem found and corrected? | -- | -- | |
13 |
Did the amber ABS warning indicator turn ON for 3 seconds and then turn OFF? | -- | System OK | Go to Diagnostic System Check |
