Diagnostic Instructions
DTC Descriptor
DTC P0501: Vehicle Speed Sensor (VSS) Circuit
Circuit/System Description
The vehicle speed information is provided to the engine control module (ECM) by the vehicle speed sensor (VSS). The VSS is a permanent magnet generator that is mounted to the transmission and produces a pulsing voltage. The AC voltage amplitude and frequency
increases with vehicle speed. The ECM converts the pulsing voltage into km/h (mph).
Conditions for Running the DTC
European Emissions
| • | The engine speed is more than 2,500 RPM. |
| • | The air flow into the engine is greater than 180 mg/tdc. |
| • | The DTC runs continuously when the above conditions are met. |
Non-European Emissions
| • | High manifold absolute pressure readings. |
| • | The DTC runs continuously when the above conditions are met. |
Conditions for Setting the DTC
European Emissions
The ECM does not detect vehicle speed for more than 25 seconds.
Non-European Emissions
The ECM does not detect vehicle speed for a long period of time.
Action Taken When the DTC Sets
DTC P0501 is a Type A DTC
Conditions for Clearing the DTC
DTC P0501 is a Type A DTC
Diagnostic Aids
| • | Ensure the VSS is correctly torqued to the transmission housing. |
| • | This DTC may be set due to an instrument panel (IP) cluster condition. |
Reference Information
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Component Connector End Views
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Raise the drive wheels.
Notice: Support the lower control arms in the normal horizontal position in
order to avoid damage to the drive axles. Do not operate the vehicle in gear
with the wheels hanging down at full travel.
- Support the lower control arms so that the drive axles are in a horizontal position.
- Engine running, engage the transmission into 2nd gear.
- Observe the scan tool VSS data parameter. The following should display a vehicle speed once the drive wheels are at a speed above 5 km/h (3 mph):
- 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 data.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the VSS.
- Ignition ON, test for less than 0.1 volt between the ground circuit terminal A and ground.
| ⇒ | If greater than the specified range, repair the ground circuit for an open/high resistance. |
- Connect a test lamp between the ignition 1 voltage circuit terminal B and ground circuit terminal A.
- Command the fuel pump relay ON with a scan tool. Test for battery voltage between the ignition 1 voltage circuit and ground.
| ⇒ | If less than B+, repair the ignition 1 voltage circuit for a short to ground or an open/high resistance. |
- Test for 9-11 volts between the signal circuit terminal C and ground.
| ⇒ | If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM. |
| ⇒ | If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM. |
- If the voltage is within the specified range, test or replace the VSS.
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.
