The transmission pump is responsible for turning the rotational force created by the engine, into the hydraulic pressure that operates the transmission and turns your vehicle’s drive wheels. If the hydraulic pump relay circuit is not performing according to the preset parameters programmed into the ECU, a P0946 DTC will be saved.
How Serious is the Code?
A P0946 diagnostic trouble code means that the hydraulic pump relay/transmission pump relay may not be working right, which could impact the performance of the transmission pump itself. This could create a number of drivability issues, as well as cause severe/expensive damage.
Symptoms of a P0946 include:
- Usually harsh gear changes
- Slipping between gears
- Transmission will not change gears
- Dirty transmission fluid/filter
- Low transmission fluid level
- Damaged wiring and/or connectors
- Hydraulic pump relay has failed
- ECU or TCM issues
How to Diagnose the Code?
When diagnosing a P0946 OBDII trouble code, the hydraulic pump relay should be tested to be sure that it is working. If it is, the transmission fluid level and condition should be checked. The wiring and connectors between the relay panel and the transmission panel should also be checked for signs of damage and corrosion.
What Repairs Will Fix P0946?
- Change transmission fluid/filter
- Repair or replace damaged wiring and/or connectors
- Replace hydraulic pump relay
- Reprogram or replace ECU/TCM