DTC 94, Brake Switch Contacts Always Closed: Notes

This test checks for proper brake switch operation. This is important because ABS is activated when brake switch is on and turned off when brake switch is off. If brake switch is always on, ABS operation will always be requested, resulting in potential modulator cycling on rough roads. This failure will result in a dead battery, due to brakelights staying on. ABS warning light will flash to indicate malfunction, but ABS will not be disabled.

NOTE: Test numbers refer to numbers on diagnostic chart. To identify circuits and terminals referenced in text and flowcharts, see WIRING DIAGRAM .

Fig 1: DTC 94 Diagnostic Flow Chart

Courtesy of GENERAL MOTORS CORP.

This checks if malfunction is currently present.
Isolates cause of malfunction to either a malfunctioning or misadjusted brake switch, or a short to voltage in brake switch circuitry.
Checks for unwanted voltage on brake switch input circuit.
Ensures fault was not due to poor terminal contact or EBCM.