Shift Solenoid C Intermittent
Diagnostic Trouble Code P0764 indicates that the Powertrain Control Module (PCM) or Transmission Control Module (TCM) has detected an intermittent electrical issue or erratic performance from Shift Solenoid 'C'. The module sets this code when the voltage or resistance in the shift solenoid 'C' circuit fluctuates outside of the expected parameters intermittently.
While the vehicle may still be drivable, an intermittent shift solenoid issue can cause erratic shifting and potentially lead to internal transmission damage if ignored. It should be diagnosed and repaired as soon as possible to prevent being stranded or causing further damage.
Common symptoms
- Check Engine Light is illuminated
- Harsh, delayed, or erratic transmission shifting
- Transmission slipping between gears
- Vehicle stuck in a specific gear (limp mode)
- Decreased fuel economy
Likely causes
- Low or dirty transmission fluid
- Faulty or failing Shift Solenoid 'C'
- Corroded, damaged, or loose wiring and connectors in the solenoid circuit
- Clogged transmission filter or internal fluid passages
- Faulty Transmission Control Module (TCM) or Powertrain Control Module (PCM)
What to check before replacing parts
Check the transmission fluid level and condition.
Look for: Fluid that is low, burnt, or heavily contaminated with debris indicates a fluid issue that could cause erratic solenoid operation or internal transmission problems.
Inspect the wiring harness and connectors for Shift Solenoid 'C'.
Look for: Look for frayed wires, melted insulation, corrosion in the connector pins, or loose connections that could cause an intermittent electrical fault.
Test the resistance of Shift Solenoid 'C' using a digital multimeter.
Look for: Compare the measured resistance to the manufacturer's specifications. An out-of-spec or fluctuating reading indicates a faulty solenoid.
Check the solenoid circuit for continuity and shorts to ground.
Look for: A lack of continuity or a short to ground in the wiring between the TCM/PCM and the solenoid indicates a wiring harness failure.
Command the solenoid on and off using a bi-directional scan tool.
Look for: Listen for a definitive 'click' from the transmission pan area and monitor the scan tool data to see if the TCM recognizes the state change. No click or erratic data suggests a failed solenoid or TCM issue.
This page explains the generic P0764 definition and is general reference information, not a diagnosis for your specific vehicle. Actual causes, severity, and repairs vary by make, model, engine, and mileage — always confirm with a scan tool and a qualified technician before replacing parts.
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