P0501

DTC P0501 (Diesel Only)








Refer to the VSS Circuit part of Engine Controls Schematics.

Circuit Description
The speed sensor circuit consists of a magnetic induction type sensor, a vehicle speed sensor buffer module and wiring. Gear teeth pressed on the output shaft induce 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, cruise control, antilock brake and PCM. The buffer sends two different signals to the PCM.

Conditions for Setting the DTC
^ The PCM performs this DTC diagnostic continuously.
^ The vehicle speed is greater than 32 km/h (20 mph).
^ The four wheel low is not selected.
^ The VSS buffer calculated speed is less than half the transmission calculated speed.
^ All of the Conditions for Setting the DTC are met for 2 seconds
^ The PCM performs this DTC diagnostic continuously.
^ The VSS buffer calculated speed is greater than transmission calculated speed by 32 km/h (20 mph).
^ All of the diagnostic set conditions met for 2 seconds.

Action Taken When the DTC Sets
^ The PCM disallows all cruise control inputs.
^ The PCM will not illuminate the Malfunction Indicator Lamp (MIL).
^ The PCM records the operating conditions at the time the diagnostic fails. This information stores in the Failure Records.

Conditions for Clearing the MIL/DTC
^ A History DTC will clear when 40 consecutive warm-up cycles, during which the diagnostic does not fail, coolant temperature has risen 5°C (40°F) from the start up coolant temperature, and the engine coolant temperature exceeds 71°C (160°F) during that same ignition cycle.
^ A scan tool can clear the MIL/DTC.

Test Description
The numbers below refer to the step numbers on the Diagnostic Table.
3. This tests for B+ at VSS buffer.
4. This tests for proper ground path for vehicle speed sensor signal buffer.