Deceleration Sensor Diagnostics
NOTE:
During deceleration sensor diagnosis, ABS functions like a standard brake system.
- Ensure battery is fully charged. Turn ignition on. ABS warning light should illuminate, then turn off after 3 seconds. If ABS warning light does not illuminate, check fuse, bulb, and wiring harness. See ABS WARNING LIGHT CIRCUIT under CIRCUIT TESTS.
- Turn ignition off. DO NOT remove short pin from DLC1. Connect a fused jumper wire between DLC1 terminals E1 and Ts. See Figure. Apply parking brake. Depress and hold brake pedal. Start engine.
- ABS warning light should flash 4 times per second. If ABS warning light flashes, go to next step. If ABS warning light does not flash, go to ABS WARNING LIGHT CIRCUIT under CIRCUIT TESTS. A deceleration sensor malfunction will cause ABS warning light to flash DTC 79.
- To inspect deceleration sensor detection point, slowly raise rear of vehicle and measure height from center of lower body of vehicle to ground. See Fig 1. Verify ABS warning light is off. If light is on, inspect deceleration sensor installation. Repair if necessary. If deceleration sensor installation is okay, replace deceleration sensor.
- Slowly lower rear of vehicle. Slowly raise front of vehicle and measure height from center of lower body of vehicle to ground. Verify ABS warning light is off. If ABS warning light is on, inspect deceleration sensor installation. Repair if necessary. If deceleration sensor installation is okay, replace deceleration sensor.
- Slowly lower vehicle. To inspect sensor operation, drive vehicle at speeds of 12 MPH or greater. Depress brake pedal lightly. ABS warning light should flash 4 times per second with no change in pattern.
- Drive vehicle at speeds of 12 MPH or greater. Using moderate force, depress brake pedal. ABS warning light should remain on during braking and return to normal pattern when released.
- Drive vehicle at speeds of 12 MPH or greater. Depress brake pedal firmly, then release it. During braking, ABS warning light should illuminate briefly, start to flash 4 times per second, then illuminate briefly once more. After brake pedal is released, ABS warning light returns to normal pattern.
- If ABS warning light does not function as described, check deceleration sensor installation. If sensor installation is okay, replace deceleration sensor. Turn engine off. Remove jumper wire from DLC1.