Ford 634 Manual lever position sensor voltage higher or lower than expected

How to read it

Code 634 reads as 6 flashes, pause, 3 flashes, pause, 4 flashes on the check-engine light. Jumper the self-test input to signal return at the test connector, then run the key on engine off self test and the running self test, counting the check-engine flashes each time.

What does Ford code 634 mean?

Manual lever position sensor voltage higher or lower than expected

Common causes of 634

• The manual lever position sensor is out of adjustment
• An open or short in the manual lever position sensor circuit
• A failed transmission range sensor
• An internal fault in the PCM manual lever position input

How to fix 634

1. Check the manual lever position sensor adjustment and the shift linkage
2. Check the sensor circuit wiring for an open or short
3. Test the transmission range sensor and replace it only if it fails its own test
4. Test the PCM last, only after every circuit test has passed
5. Clear the code, then retest to confirm the fix holds

Source

Qualified source review