C1203

DTC C1203 Right Front Wheel Speed Sensor Circuit Open or Shorted






Circuit Description
As the wheel is rotated, the speed sensor produces an AC voltage that increases with wheel speed. The EBCM uses the frequency of the AC signal to calculate wheel speed. The speed sensor is connected to the EBCM by a twisted pair of wires. Twisting reduces noise susceptibility that may cause a DTC to set.

Conditions for Setting the DTC
DTC C1203 can be set anytime the key is on and the EBCM has detected an open, short to ground or a short to battery on the right front wheel speed circuit.

Action Taken When the DTC Sets
^ The solenoid relay opens, removing power to the pump motor and solenoids.
^ DTC C1203 is stored.
^ ABS disabled, ABS Warning Lamp turns on.

Conditions for Clearing the DTC
^ If the conditions that set DTC C1203 are no longer present, the DTC may be cleared by using the proper scan tool.
^ The DTC that has not occurred in 100 drive cycles will be cleared from history data.

Diagnostic Aids
Thoroughly inspect the wiring and connectors when diagnosing intermittent DTC(s). This will include the following.
^ Removal of the protective conduit and inspection for wiring for damage, shorts and contamination.
^ Inspection for improperly formed and/or damaged terminals.
^ Checking terminal contact (retention force) by using a spare male/female terminal.
^ Removal of the terminals from the connectors to check for proper terminal to wire crimp.

If the drivers comments reflect that the ABS Warning Lamp is on only during moist environmental changes (rain, snow, vehicle wash), all wheel speed sensor circuitry should be thoroughly inspected for signs of water intrusion. If the DTC is not current, simulate the effects of water intrusion. Use the following procedure. Spray the suspected area with a 5% salt-water solution. Then test-drive the vehicle over various road surfaces such as (bumps, turns, etc.) above 24 kph (15 mph). If the DTC sets then replace the suspected harness and or sensor.

When measuring wheel speed sensor resistance insure the vehicle is at room temperature, since resistance will increase with temperature. Failure to perform the previous steps carefully and fully can result in misdiagnosis, unnecessary component replacement and reoccurrence of DTC C1203.








DTC Troubleshooting