DP1 - Complete VSS Drive Cycle

Continuous Memory DTC 29 or 452 indicates that sometime during the last 40 or 80 warm-up cycles, the Powertrain Control Module (PCM) detected an error in the vehicle speed sensor output signal.

Possible causes:

- Damaged Vehicle Speed Sensor (VSS).

- Damaged harness circuits.

- Damaged Powertrain Control Module (PCM).

- Perform VSS Drive Cycle at least three times as outlined below.

VEHICLE SPEED SENSOR DRIVE CYCLE:

- Record and clear continuous memory Diagnostic Trouble Codes (DTC). Quick Test Appendix (Detailed Testing Instructions)

- Warm engine to operating temperature.

AUTOMATIC TRANSMISSIONS:

- Place gear selector in Drive range.

- Obey all local traffic laws. Accelerate heavily to 35 mph.

- Coast down to an idle and stop the vehicle.

- Shut the engine "OFF".

- After the drive cycle is completed, run Key On Engine Off (KOEO) Self-Test and record the Continuous Memory DTCs displayed. Quick Test Appendix (Detailed Testing Instructions)

MANUAL TRANSMISSIONS:

- From first gear, shift to second.

- Obey all local traffic laws. Accelerate moderately to 40 mph.

- Coast down to an idle and stop the vehicle.

- Shut the engine "OFF".

- After the drive cycle is completed, run KOEO Self-Test and record the Continuous Memory DTCs displayed. Quick Test Appendix (Detailed Testing Instructions)

- Did Continuous Memory DTC 29 or 452 repeat?

Yes -- Go to DP2. DP2 - Check Continuity of Vehicle Speed Sensor Harness Circuit

No -- Unable to duplicate and/or identify fault at this time. For further diagnosis, refer to Diagnosis by Symptom (Diagnostic Routines). All others, clear continuous memory. Clearing Diagnostic Trouble Codes