TD10 - Diagnostic Trouble Code 634

Continuous Memory Diagnostic Trouble Code (DTC) 634 indicates that the Powertrain Control Module (PCM) has detected an invalid combination of transmission range switch states.

NOTE: Park/Neutral Position (PNP) switch is considered a transmission range switch in this Pinpoint Test.

- Test drive vehicle with gear selector in both Drive (0) and Overdrive (OD) positions. Check to see if transmission is always in 3rd gear with selector in the D or OD position.

- With the gear selector in D and OD position, is transmission always in 3rd gear?

Yes -- Go to TD11. TD11 - Check For IGN START/RUN Voltage at Transmission

No -- If symptom is "Transmission stays in 3rd gear occasionally," Go to TD20. TD20 - Visually Check EEC-IV Harness to Transmission

For all other symptoms, disregard Continuous DTC 634. Clear continuous memory. Clearing Diagnostic Trouble Codes

Return to Diagnosis by Symptom (Diagnostic Routines) to address symptom/other DTCs as necessary.