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).

The ECM detects that the vehicle speed is less than 5 km/h (3.1 mph) for more than 3 seconds.

DTC P0501 is a Type A DTC.

DTC P0501 is a Type A DTC.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

1. 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.

2. Support the lower control arms so that the drive axles are in a horizontal position.
3. Start and idle the engine.

Engine Idling. Engage the transmission into 2nd gear.

4. Observe the VSS data parameter with a scan tool. The following should display a vehicle speed once the drive wheels are at a speed above 5 km/h (3 mph):

•	The VSS data parameter

•	The speedometer

5. If the vehicle passes the Circuit/System Verification Test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records Data List.

1. Ignition OFF, disconnect the harness connector at the VSS.
2. Connect a test lamp between the ignition 1 voltage circuit of the VSS and ground.
3. Ignition ON, verify that a test lamp illuminates between the ignition 1 voltage circuit and battery ground.

⇒	If the test lamp does not illuminate, test the ignition 1 voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition 1 voltage circuit fuse is open, test all components connected to the ignition 1 voltage circuit and replace as necessary.

4. Ignition OFF, test for less than 5.0 ohms of resistance between the ground circuit and ground.

⇒	If greater than 5.0 ohms repair the ground circuit for an open/high resistance.

5. Ignition ON, test for 9-11 volts between the signal circuit of the VSS and the negative terminal of the battery.

⇒	If less than 9 volts test the VSS signal circuit for a short to ground or an open/high resistance. If the circuit/connections test normal, replace the ECM.

⇒	If greater than 11 volts, test the VSS signal circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.

6. If the voltage is within the specified range replace the VSS.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.