The gear shift lock solenoid is a little device that sends a signal to release the transmission from Park when you press the gear shift lock button. If there is an unusually high-voltage signal on the circuit that this solenoid operates on, a P0931 DTC will be saved.
How Serious is the Code?
A P0931 diagnostic trouble code is actually pretty serious, because if the gear shift lock solenoid is not working properly, may not be able to shift out of Park.
Symptoms of a P0931 include:
- It becomes difficult or impossible to shift the transmission into or out of reverse
- Transmission fluid has gotten too low or too dirty
- The battery voltage is too low
- Bad fuse(s) or fusible link(s)
- Connector or wiring damage
- Gear shift lock solenoid has failed
- Brake light switch has failed
How to Diagnose the Code?
Believe it or not, low/dirty transmission fluid and low battery voltage can actually cause a P0931 OBDII trouble code, so the diagnostic procedure should begin with checking both of those areas. Any fuses or fusible links related to the shifter mechanism should also be checked, along with the wiring and connectors around the shift mechanism. The gear shift lock solenoid itself may also have to be tested, along with possibly the brake light switch.
What Repairs Will Fix P0931?
- Change the transmission fluid/filter
- Charge or replace the battery
- Replace any blown fuses or fusible links
- Replace any damage wiring or connectors
- Replace gear shift interlock solenoid
- Replace brake light switch