DTC 87: Brake WARING Light Circuit Open Or Shorted To Battery: Description

DTC 87 can be set after vehicle speed exceeds 5 MPH or when EBCM turns on "BRAKE" warning light because of bulb check. A malfunction exists if "BRAKE" warning light circuit voltage is not within specification.

1. Turn ignition on. If "BRAKE" warning light is illuminated, go to next step. If "BRAKE" warning light is not illuminated, go to step 3).
2. If DTC 86 is also set, go to DTC 86: EBCM TURNED ON THE BRAKE WARNING LIGHT. If DTC 86 is not set with DTC 87, inspect brake fluid level. Correct as needed. Inspect parking brake switch. Repair or replace as needed.
3. Turn ignition on. Release parking brake. Using scan tool, select data list function. Monitor "BRAKE" warning light status. If scan tool displays CIRCUIT OPEN, go to next step. If scan tool does not display CIRCUIT OPEN, go to step 7).
4. Using scan tool, select lamp function. Command "BRAKE" warning light on. If "BRAKE" warning light is illuminated, inspect Red/Black wire between EBCM and instrument cluster 13-pin harness connector for poor terminal connections or high resistance. Repair as needed. If "BRAKE" warning light is not illuminated, go to next step.
5. Inspect operation of instrument panel indicator lights. Refer to vehicle owner's manual. If all lights are functioning correctly, go to next step. If lights are not functioning correctly, see INSTRUMENT PANEL article in ACCESSORIES/SAFETY EQUIPMENT section.
6. Turn ignition switch to LOCK position. Disconnect EBCM harness connectors. Turn ignition switch on. Connect jumper wire between ground and terminal No. 17 (Red/Black wire) on EBCM 24-pin harness connector. If "BRAKE" warning light is illuminated, inspect harness connector. Ensure connector is clean and tight. If harness connector is okay, replace EBCM. If "BRAKE" warning light is not illuminated, inspect indicator light bulb. Replace as needed. If bulb is okay, inspect Black/White wire between IG fuse and instrument cluster. Repair as needed.
7. Turn ignition switch to LOCK position. Remove IG fuse. Disconnect EBCM harness connectors. Turn ignition switch on. Release parking brake. Measure voltage between ground and terminal No. 17 (Red/Black wire) on EBCM 24-pin harness connector. If voltage is one volt or less, go to next step. If voltage is greater than one volt, repair Red/Black wire for short to voltage.
8. Turn ignition switch to LOCK position. Install IG fuse. Turn ignition switch on. Apply parking brake. Measure voltage between ground and terminal No. 17 (Red/Black wire) on EBCM 24-pin harness connector. If voltage is one volt or less, go to next step. If voltage is greater than one volt, repair parking brake switch circuit for high resistance.
9. Turn ignition switch to LOCK position. Reconnect EBCM harness connectors. Release parking brake. Turn ignition switch on. Using scan tool, clear DTCs. See CLEARING CODES . If DTC 87 resets, replace brake fluid level switch. If DTC 87 does not reset, system is currently functioning correctly. See DIAGNOSTIC AIDS .