DTC 87

DTC 87 Red BRAKE Warning Lamp Circuit Open:

Circuit Description:
This DTC is used to verify the 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.

DTC Will Set When:
DTC 87 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.

DTC Chart Test Description:
Number(s) below refer to circled number(s) on the diagnostic chart.
1. Identifies if the ground circuit to the red "BRAKE" warning lamp is completed by a source other than the EBCM.
2. Checks for high resistance in park brake circuitry.
3. Checks for a malfunctioning EBCM.
4. Checks for high resistance in fluid level switch circuitry.
5. Checks for a malfunctioning warning lamp bulb.
6. Checks for open or high resistance in CKT 33.

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-1OO 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.