Electric/Auxiliary Transmission Fluid Pump Phase U-V-W Circuit Low

Where it lives

For P0C21, the circuit described runs through the pump. The description of P0C21 reports a fault at the pump.

Check these first

• Low battery voltage at the pump phase circuit
• An open in the pump phase U-V-W wiring
• A short to ground in the pump phase circuit
• A failing aux transmission fluid pump

What to do next

1. Read the aux fluid pump phase voltage on a scan tool
2. Check battery voltage and charging
3. Test the pump phase U-V-W wiring for an open
4. Test the pump phase circuit for a short to ground
5. Replace the aux fluid pump if the circuit tests good
6. Clear the code and retest

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