C1291 - Open Brake Lamp Switch Contacts During Deceleration

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CIRCUIT DESCRIPTION
DTC C1291 detects an open brake switch in the non-ABS mode. The EBTCM looks for deceleration rates that may indicate braking action. The EBTCM verifies braking action by repeating the method for finding deceleration rates that indicate braking action several times. In each case, the ABS will not be available because the EBTCM does not see the brake switch input.

CONDITIONS FOR SETTING THE DTC
DTC C1291 can set if three deceleration cycles within the specified rate occur during the current ignition cycle with the brake switch off.

ACTION TAKEN WHEN THE DTC SETS
- A malfunction DTC stores.
- The ABS/ETS disables.
- The amber ABS/ETS warning indicators turns on.

CONDITIONS FOR CLEARING THE DTC
- The condition responsible for setting the DTC no longer exists and the Scan Tool Clear DTCs function is used.
- 100 drive cycles pass with no DTCs detected.

DIAGNOSTIC AIDS
If the malfunction is not current, use wiggle test on the wiring harness to pinpoint an intermittent malfunction in the motor circuitry or connections. Thoroughly inspect any circuitry that may be causing the intermittent complaint for the following conditions:
- Backed out terminals
- Improper mating
- Improperly formed or damaged terminals
- Poor terminal-to-wiring connections
- Physical damage to the wiring harness
- Rubbed-through wire insulation
- A broken wire inside the insulation