C1257

DTC C1257: G Sensor Faulty (4 Wheel Drive Vehicles Only)






Circuit Description
Battery voltage is supplied to G sensor from switched ignition to E37-1. EBCM is connected to G sensor by a ground circuit and a signal circuit.
G sensor converts forward and rearward motion into a voltage signal used by EBCM for an additional speed reference.
With vehicle in Park, or at steady speed, the voltage signal will range from 2.4 to 2.6 volts.
During forward acceleration voltage will increase, during deceleration voltage will decrease.

DTC Detecting Condition
DTC C1257 can only be set when the vehicle is in 4 Wheel Drive and one of the following occur.
- Voltage signal from G sensor is greater than 4.5 volts or less than 0.5 volts for 3/4 of a second.
- Any wheel speed is at zero and the G sensor signal voltage is between 0.5 and 1.04 volts for 3/4 of a second.

Action Taken When the DTC Sets
- ABS relay open, removing power from pump motor and solenoids.
- DTC C1257 is stored.
- ABS disabled, ABS warning light turns on.

Diagnostic Aids
Typical Causes of DTC C1257.
- Open, short to ground or a short to power on any one of accelerometer circuits.
- Accelerometer not secured to vehicle.
- Faulty Accelerometer.
- Faulty EBCM.

DTC Troubleshooting





NOTE: "ABS Check: Type 1 " must be performed first before using this flow.