P0503

P0503-VEHICLE SPEED SENSOR 1 ERRATIC

For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

The vehicle speed sensor rationality is a continuous test that monitors the vehicle speed sensor for lack of activity. The rationality will not run if a limp-in exists for MAP, Throttle Position, Crankshaft Sensor, Camshaft Sensor, and Engine Coolant Temperature. If vehicle speed sensor is below a minimum threshold for a period of time after the vehicle is operated at a sufficient load, a failure will be indicated.

- When Monitored:
Ignition on and battery voltage greater than 10 volts. Transmission in Drive or Reverse.

- Set Condition:
This code will set if no vehicle speed signal is received from the ABS Module up to 120 seconds for 2 consecutive trips. One Trip Fault. Three good trips to turn off the MIL.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

Diagnostic Test

1. ACTIVE DTC
1. Start the engine.
2. Test drive the vehicle.
3. With a scan tool, select View DTCs.

Are there any Active or Pending DTCs related to vehicle or wheel speed in any other module?

Yes

- Refer to the Diagnosis and Testing section of the module with active DTC and perform the diagnostic test procedure.

No

- Go To 2

2. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Vehicle Speed Sensors, ABS Module, and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched, or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the Vehicle Speed Sensors, ABS Module, and Powertrain Control Module connectors.
4. Perform any Technical Service Bulletins that may apply.

Were there any problems found?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Replace and program the Powertrain Control Module (PCM). Powertrain Control Module - Removal.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.