Auxiliary Transmission Fluid Pump Phase U-V-W Circuit High
The P0C22 code indicates a high voltage condition detected in the auxiliary transmission fluid pump's phase U-V-W circuit. This pump is responsible for circulating transmission fluid when the engine is off (e.g., in hybrid vehicles) to maintain lubrication and cooling. A high voltage reading suggests a short to power, faulty pump motor, or a problem with the pump control module.
1. Symptoms You Will Notice
- Transmission overheating or slipping
- Check Engine Light illuminated
- Reduced fuel economy or hybrid system warning
2. Most Common Causes
- Short to battery voltage in the pump wiring or connector
- Faulty auxiliary transmission fluid pump motor
- Malfunctioning transmission control module (TCM) or pump driver circuit
3. Step-by-Step Diagnosis
Step 1: Use a scan tool to retrieve freeze frame data and verify the code.
Step 2: Inspect the auxiliary pump wiring and connector for damage, corrosion, or shorts to power.
Step 3: Measure voltage at the pump connector with the ignition on; compare to specifications.
Step 4: Test the pump motor resistance and check for continuity to ground.
Step 5: If wiring and pump are okay, test the TCM output signals or replace the TCM.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
No, driving with this code can cause transmission damage due to inadequate lubrication and cooling, especially in hybrid vehicles that rely on the auxiliary pump when the engine is off.
How much does it cost to fix?▼
Diagnosis typically costs $50-$150. Repair costs vary: wiring repair $100-$300, pump replacement $200-$500, TCM replacement $500-$1000.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.