Displays and Gages
DTC P0503
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.
DTC Descriptors
DTC P0503
- Vehicle Speed Sensor (VSS) Circuit Intermittent
Diagnostic Fault Information
Circuit/System Description
The vehicle speed signal is provided to the engine control module by the vehicle speed sensor (VSS). The ECM provides a 5 V reference, low reference, and signal circuit to the VSS. The VSS provides a frequency signal that is proportional to the vehicle speed.
Conditions for Running the DTC
* Ignition voltage is between 11 V and 18 V.
* Raw output speed is greater than 3000 RPM.
* Output speed change is less than 175 RPM.
Conditions for Setting the DTC
Loop to loop change in TOSS is greater than 3000 RPM.
Action Taken When the DTC Sets
DTC P0503 is a type B DTC.
Conditions for Clearing the DTC
DTC P0503 is a type B DTC.
Reference Information
Schematic Reference
* Automatic Transmission Controls Schematics (Diagrams)
* Manual Transmission Schematics (D16 - Manual Transmission) for the D16 transmission
* Manual Transmission Schematics (Y4M) (Y4M - Manual Transmission) for the Y4M transmission
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
* Electronic Component Description (Electronic Component Description)
* Transmission System Description and Operation (Transmission System Description and Operation) for the D16 transmission
* Transmission System Description and Operation (Description and Operation) for the Y4M transmission
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
1. Operate the vehicle at 16-32 km/h (10-20 mph) while observing the scan tool VSS parameter. The reading should vary with the vehicle speed and not drop out.
2. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observes from the Freeze Frame/Failure Records data.
Circuit/System Testing
1. Ignition OFF, disconnect the VSS harness connector.
2. Test for less than 5 Ohms between the low reference circuit terminal A and ground.
• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal replace the ECM.
3. Ignition ON, test for greater than 4 V between the 5 V reference circuit terminal C and ground.
• If less than the specified value, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal replace the ECM.
4. Ignition ON, test for greater than 4 V between the signal circuit terminal B and ground.
• If less than the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal replace the ECM.
5. If all circuits test normal replace the VSS.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the repair.
Control Module References (Programming and Relearning) for ECM replacement, setup, and programming