DTC 87

87 RED "BRAKE" WARNING LAMP CIRCUIT OPEN/SHORTED TO BATTERY

DTC 87 Red Brake Warning Lamp Circuit Open Or Shorted To Battery (Part 1 Of 2):

DTC 87 Red Brake Warning Lamp Circuit Open Or Shorted To Battery (Part 2 Of 2):

DTC 87 Red Brake Warning Lamp Circuit Open Or Shorted To Battery:

Circuit Description:
This DTC identifies a open or short to voltage between the EBCM and the red BRAKE warning lamp, or an open driver that does not allow the red BRAKE warning lamp to be illuminated by the EBCM. 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 brake fluid level switch or may also turn "ON" the red BRAKE warning lamp) a short to ground in this circuit cannot be detected.

DTC Will Set When:
DTC 87 can be set during the three second bulb check and after initialization is completed. If the red BRAKE warning lamp circuit voltage is out of specification indicating an open circuit or a short to voltage, a malfunction exists.

Action Taken:
A malfunction DTC is stored, ABS is not disabled, however, if the EBCM commands the red BRAKE warning lamp on due to a ABS malfunction that may degrade base brake operation and cannot do so the ABS warning lamp will flash to indicate the serious nature of the problem.

DTC Chart Test Description:
Number(s) below refer to circled number(s) on the diagnostic chart.
1. Checks whether the BRAKE warning lamp circuitry is open or shorted to voltage.
2. Checks the complete BRAKE warning lamp manually turn
3. Checks for high resistance in park brake circuitry.
4. Checks for a malfunctioning EBCM.
5. Ensures malfunction is not due to poor terminal contact at the brake fluid level switch which may result in an intermittent.
6. Checks the integrity of the "BRAKE" warning lamp.
7. Checks for high resistance in the "BRAKE" warning lamp control circuitry.
8. Identifies if a malfunction is currently present.
9. With the Tech 1 connected, attempts to turn "ON" the "BRAKE" warning lamp.
10. Checks for a short to voltage in CKT 33.
11. Ensures malfunction was not due to physical damage of the circuitry.
12. Checks for DTC 86 also being set.

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 is 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 of 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.