What does it mean?
P1824 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Internal Mode Switch P Circuit High Voltage .
Symptoms
- Check engine lamp on and the gear display never shows P
- No crank in Park, though the engine may start in Neutral
- Shift interlock behaving oddly and the selector locking or releasing at the wrong time
- Transmission defaults to a fixed gear with harsh engagement
- Limp mode and noticeably reduced drivability
Likely causes
- Open circuit in the Park wire between the mode switch and the module
- High resistance from a corroded terminal in the external case connector
- Park contact inside the switch burnt, worn away or permanently open
- Internal harness broken or its connector partly unlatched after service
- Poor switch ground path so no track can pull low
- Failed mode switch assembly
- Module input circuit open internally
How to fix it
- Read the codes and watch the Park state on the scan tool while the selector sits in Park
- Check the external case connector for corroded, backed-out or loose terminals
- Test the Park wire for continuity from the module connector to the case connector
- Jumper the Park circuit to ground at the case connector and see whether the state changes on the scan tool, which isolates switch from wiring
- If the state changes, the fault is inside the unit: drop the pan and inspect the internal harness and switch
- Verify the switch ground circuit and its alignment to the manual shaft
- Replace the mode switch or repair the harness accordingly, then verify all ranges read correctly