For vehicles equipped with 4 Wheel Drive and an automatic transmission, a park/neutral sensor is used to notify the ECU when the transmission is shifted out of gear. If it does not have this information, the transmission may not shift right, and the ECU can prevent the 4WD system from engaging. If the ECU detects an unusually high voltage signal coming from the input circuit, a P0852 DTC will be stored.
How Serious is the Code?
A P0852 diagnostic trouble code is fairly serious, because the computer has to know the selected gear in order to shift gears properly. The transmission also has to be in park or neutral in order for the four-wheel-drive system to engage.
Symptoms of a P0852 include:
- Unable to engage four wheel drive
- Hard shifts
- Failure to shift
- Damaged wiring and connectors
- Sensor retaining bolts not installed correctly
- Failed park/neutral sensor
- Transfer case range sensor out of adjustment
- Faulty transmission range sensor
How to Diagnose the Code?
In order to diagnose a P0852 OBDII trouble code, the technician will need to inspect the wiring and connectors. The park/neutral switch itself will also need to be tested for proper voltage flow and ground. If no problems have been found, then the transmission range sensor and transfer case range sensor will need to be tested.
What Repairs Will Fix P0852?
- Repair or replace damaged wiring and connectors
- Replace Park/Neutral switch
- Adjust transfer case range sensor
- Replace transmission range sensor
- Install new sensor retaining bolts
- P0850 – Park/Neutral Switch Input Circuit
P0851 – Park/Neutral Switch Input Circuit Low
P0853 – Drive Switch Input Circuit
P0854 – Drive Switch Input Circuit Low