Auxiliary Transmission Fluid Pump Motor Phase U has High Current
What it means
The pump control circuit reports high current in phase U of the auxiliary transmission fluid pump motor. This electric pump keeps fluid moving when the engine is off, such as at stop-start stops. High current usually means a short or a pump that is binding.
Can I keep driving? Usually yes in the short term, but the transmission may get too little fluid at stops, so get it read soon.
What this part does
The auxiliary electric transmission fluid pump supplies transmission fluid pressure when the engine is stopped, such as during an engine start-stop event or while a hybrid runs on electric power. The transmission control module switches it on so clutches stay filled and shifts stay smooth. Some designs work with high voltage, where service is for trained people. A fault can cause delayed engagement or rough starts from rest.
Common symptoms
What you'll notice
- Hybrid or transmission warning light on
- Engine stop-start not working
- Delayed or rough take-off after a stop
Common causes
Most likely first
- Wiring or connector fault between the pump control unit and the motor
- Worn or failing pump motor
- Low or contaminated transmission fluid
- Pump control module fault
How to diagnose & fix
Work through it in order
- Read all codes, including other pump-phase codes.
- Check transmission fluid level and condition.
- Inspect the pump connector and wiring for corrosion or damage.
- With a scan tool that supports it, run the pump test and listen for the motor.
- Do not open the battery pack or touch orange high-voltage cables; leave any high-voltage testing to a trained technician.
Related codes
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