A087

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION
This DTC is used to verify the Electronic Brake Control Module (EBCM) has continuity to the red brake warning lamp in case the EBCM must turn it "ON." This will only occur if an ABS malfunction is detected that may degrade base brake operation.

Because ABS is not the only device controlling the red brake warning lamp (parking brake and low fluid sensor may also turn "ON" the lamp) a short to ground in this circuit cannot be detected.

FAILURE CONDITION
DTC A087 can be set after initialization is completed. If the red brake warning lamp circuit voltage is out of specification indicating an open circuit, a malfunction exists.

ACTION TAKEN
A malfunction DTC is stored, ABS is not disabled; however, the ABS indicator lamp will flash to indicate a malfunction exists.

TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This step identifies if the malfunction is currently present.
2. This step indicates if the EBCM and circuitry has the ability to complete the ground to the brake telltale lamp and illuminate it.
3. Because the red brake warning lamp has current supplied to it through the 10 amp INDIC fuse, this step would indicate if the ignition circuit is complete to the lip cluster.
4. This step isolates if the open circuit is due to a EBCM failure or open circuitry to the brake telltale.
5. This step checks for an open in the park brake circuitry.
6. This step determines if the malfunction is intermittent.
7. This step verifies the condition of the INDIC fuse.

DIAGNOSTIC AIDS
An "Intermittent" malfunction may be caused by a poor connection, rubbed through wire insulation, or a wire that is broken inside the insulation.

The frequency of the malfunction can be checked by using the enhanced diagnostic function of the Tech 1. If a Tech 1 or T-100 are not available, the parking brake handle may be lifted to verify proper lamp operation and continuity of CKTs 3 and 39.

Any circuitry, that is suspected as causing the intermittent complaint, should be thoroughly checked for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wiring connections or physical damage to the wiring harness.