P0501

DTC P0501 Vehicle Speed Sensor Circuit

Circuit Description

The speed sensor circuit consists of a magnetic induction type sensor, a vehicle speed sensor buffer module and wiring. The gear teeth pressed on the output shaft induces an alternating current in the sensor. This signal is transmitted to the buffer. The buffer compensates for various axle ratios and converts the signal into a square wave for use by the speedometer, the cruise control, the antilock brake and the PCM. The buffer sends two different signals to the PCM.

Conditions for Running the DTC

^ The vehicle speed is greater than 20 mph.
^ Four wheel low is not selected.

Conditions for Setting the DTC

^ The VSS buffer calculated speed is greater than the transmission calculated speed by 20 mph.
^ All of the diagnostic set conditions met for 2 seconds

Action Taken When the DTC Sets

^ The PCM will not illuminate the Malfunction Indicator Lamp (MIL).
^ The PCM records the operating conditions at the time the diagnostic fails. This information is stored is stored in Failure Records.

Conditions for Clearing the MIL/DTC

^ A History DTC will clear after forty consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures.
^ Use of a scan tool will clear the DTC codes.

Diagnostic Aids

Check the connections at the VSS buffer and the PCM. Refer to 4L80E Diagnostic Trouble Codes if DTC P0722 or DTC P0723 is set.

Test Description

Number(s) below refer to number(s) on the Diagnostic Table.

3. This tests for 8+ at VSS buffer.
4. This tests for proper ground path for vehicle speed sensor signal buffer.