What does it mean?
P1797 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: A/T Park Neutral Range Switch Circuit Malfunction .
Symptoms
- MIL (check engine lamp) is on and the gear display shows the wrong gear, flashes or goes blank
- The engine will not crank in park but will crank in neutral, or will not crank at all
- Reverse lamps do not work, or come on in the wrong selector position
- Harsh engagement when selecting drive or reverse
- Transmission holds one gear in limp mode
- Shift interlock behaves inconsistently
Likely causes
- Transmission range switch worn internally or out of adjustment on its shaft
- Shift cable stretched or misadjusted, so the selector and the manual valve lever do not line up
- Corroded switch connector, a very exposed location on the side of the transmission
- Open, shorted or crossed wires in the multiple range signal circuits
- Water ingress into the switch itself after driving through standing water
- Loose manual valve lever or worn detent inside the transmission
- Control module input circuit fault
How to fix it
- Watch the range or gear position data while moving the selector slowly through every position, noting any position that does not register
- Check the shift cable adjustment and confirm the manual lever reaches every detent fully
- Loosen and align the range switch to its alignment marks or specified position, then retest
- Inspect the switch connector for corrosion, water and spread terminals
- Test each range circuit for continuity and for shorts to ground and to the neighbouring circuits
- Replace the range switch once wiring and cable adjustment are proven, then readjust and verify crank and reverse lamp operation