Part 1 of 3

CIRCUIT DESCRIPTION:
This DTC is used to verify the EBCM has continuity to the "BRAKE" warning light in case the EBCM must turn it on. And also, this DTC identifies a short to battery between the EBCM and the "BRAKE" warning light or an open driver that does not allow the "BRAKE" warning light 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 "BRAKE" warning light (parking brake switch and brake fluid level switch may also turn it on), a short to ground in this circuit cannot be detected.

FAILURE CONDITION:
DTC 87 can be set after vehicle speed exceeds 8 km/h (5 mph) or when the EBCM turns on the "BRAKE" warning light because of bulb check and another DTC. If the "BRAKE" warning light circuit voltage is out of specification (indicating an open circuit and shorted to battery), a malfunction exists.

ACTION TAKEN:
A DTC 87 is stored, ABS is not disabled and the "ABS" warning light will not be illuminated.

TEST DESCRIPTION:
Number(s) below refer to circled Number(s) on the diagnostic chart.
1. This step identifies if the ground circuit to the "BRAKE" warning light is being completed by a source other than the EBCM.
2. This step checks whether the malfunction is due to open in "BRAKE" warning light circuit.
3. This step indicates if the EBCM and circuitry has the ability to complete the ground to the "BRAKE" warning light and illuminate it.
4. This step checks for DTC 86 also being set.

DIAGNOSTIC AIDS:
Refer to DTC 76.