D16 - Manual Transmission
DTC P0502 or 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 P0502
- Vehicle Speed Sensor (VSS) Circuit - Low Frequency
DTC P0503
- Vehicle Speed Sensor (VSS) Circuit Intermittent
Diagnostic Fault Information
Diagnostic Fault Information
Circuit/System Description
The vehicle speed sensor is provided to the engine control module (ECM) by the vehicle speed sensor (VSS). The ECM provides a 5 volt circuit, a low reference circuit, and a signal circuit to the VSS. The VSS provides a frequency signal that is proportional to an increase in vehicle speed.
Conditions for Running the DTC
P0502
The ignition is ON.
P0503
* Ignition voltage is between 11-18 volts.
* Engine speed is between 1500-6500 RPMs.
* VSS signal is between 150-200 RPMs for 2 seconds.
Conditions for Setting the DTC
P0502
VSS signal is less than 60 RPMs for 4.5 seconds.
P0503
VSS signal is greater than 350 RPMs for 3.25 seconds.
Action Taken When the DTC Sets
P0502 and P0503 are Type B DTCs.
Conditions for Clearing the DTC
P0502 and P0503 are Type B DTCs.
Diagnostic Aids
The battery must be fully charged. Refer to Battery Inspection/Test (Battery Inspection/Test).
Reference Information
Schematic Reference
Manual Transmission Schematics (D16 - Manual Transmission)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Transmission System Description and Operation (Transmission System Description and Operation)
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
Engine Control Module Scan Tool Information (L95, LV8, LXT) (Scan Tool Testing and Procedures)
Circuit/System Verification
1. Operate the vehicle on the road at various speeds up to 64 km/h (40 mph), with a scan tool. The VSS parameter and the speedometer display on the instrument cluster should match.
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 observed from the Freeze Frame/Failure Records.
Circuit/System Testing
1. Ignition OFF, disconnect the VSS harness connector at the transmission.
2. Test for less than 5 ohms between the low reference circuit at the VSS harness connector terminal A and ground.
• If greater than the specified value, 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 volts between the 5 volt circuit at the VSS harness connector terminal C and ground.
• If less than the specified value, test the 5 volt circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
4. Ignition OFF, test for less than 1 volt on the signal circuit terminal B at the VSS harness connector.
• If greater than the specified value, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
5. Ignition OFF, disconnect the X1 connector at the ECM.
6. Ignition ON, install a 3 A fused jumper wire between B+ and terminal B at the VSS harness connector. Test for greater than 11 volts at X1 terminal 41 at the ECM harness connector.
• If less than the specified value, test the VSS signal circuit for a short to ground, or an open/high resistance. If the circuit tests normal, replace the ECM.
7. If all circuits tests normal, replace the VSS.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Engine Control Module Replacement (Service and Repair)
* (Testing and Inspection)