Code 87 - Red Brake Warning Light Circuit Open: Notes

This test verifies EBCM/EBTCM has continuity to Red BRAKE warning light. Because other systems also use this circuit, a short to ground in this circuit cannot be detected.

Code 87 can set after initialization is completed if warning light circuit voltage is out of specification, indicating an open circuit. Code will be stored but ABS will not be disabled.

NOTE: Test numbers refer to numbers on diagnostic chart. Use only 10-megohm (minimum) DVOM for all voltage and resistance tests. For identification of circuits and terminals referenced in charts and text, see WIRING DIAGRAM .

Fig 1: Code 87 Diagnostic Flow Chart

Courtesy of GENERAL MOTORS CORP.

Checks complete BRAKE warning light ground circuit.
Checks for high resistance in park brake circuit.
Checks for malfunctioning EBCM/EBTCM.
Checks for high resistance in brake fluid level sensor circuit.
Checks integrity of BRAKE warning light bulb.
Check for open or high resistance in brake warning light circuit.