Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Diagnostic Test
- CHECK IF DTC IS CURRENT
- CHECK THE (T78) BANK 1 SOLENOID POWER CIRCUIT FOR A SHORT TO VOLTAGE
- Turn the ignition off to the lock position.
- Disconnect the Transmission C1 harness connectors.
- Disconnect the TCM C1 harness connector.
- Turn the ignition on.
- Measure the voltage of the (T78) Bank 1 Solenoid Power circuit between ground and the Transmission C1 harness connector.
Is the voltage above 0.5 of a volt?
Yes
- Repair the (T78) Bank 1 Solenoid Power circuit for a short to voltage.
- Perform TRANSMISSION VERIFICATION TEST. Refer to 6F24 TRANSMISSION VERIFICATION TEST .
No
- Go To 3
- CHECK THE (T812) TORQUE CONVERTER CLUTCH PRESSURE CONTROL SOLENOID CONTROL CIRCUIT FOR A SHORT TO VOLTAGE
- Measure the voltage of the (T812) Torque Converter Clutch Pressure Control Solenoid Control circuit between ground and the Transmission C1 harness connector.
Is the voltage above 0.5 of a volt?
Yes
- Repair the (T812) Torque Converter Clutch Pressure Control Solenoid Control circuit for a short to voltage.
- Perform TRANSMISSION VERIFICATION TEST. Refer to 6F24 TRANSMISSION VERIFICATION TEST .
No
- Go To 4
- Measure the voltage of the (T812) Torque Converter Clutch Pressure Control Solenoid Control circuit between ground and the Transmission C1 harness connector.
- CHECK THE TORQUE CONVERTER CLUTCH PRESSURE CONTROL SOLENOID A (1)
- Turn the ignition off to the lock position.
- Measure the resistance of the Torque Converter Clutch Pressure Control Solenoid between the appropriate terminals of the Transmission C1 harness connector.
Is the resistance of the Torque Converter Clutch Pressure Control Solenoid 5.1 Ohms (± 0.3 Ohm) at 25° C (77° F)?
Yes
- Using the schematics as a guide, check the Transmission Control Module (TCM) pins, terminals, and connectors for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace and program the TCM in accordance with the Service Information. Refer to REMOVAL .
- Perform TRANSMISSION VERIFICATION TEST. Refer to 6F24 TRANSMISSION VERIFICATION TEST .
No
- Remove the transmission side cover and inspect the internal lead frame. If there are no problems found with the lead frame, replace the Torque Converter Clutch Pressure Control Solenoid in accordance with the Service Information.
- Perform TRANSMISSION VERIFICATION TEST. Refer to 6F24 TRANSMISSION VERIFICATION TEST .
- CHECK WIRING AND CONNECTORS
- The conditions necessary to set the DTC are not present at this time.
- Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.
- Wiggle the wires while checking for shorted and open circuits.
- Check for any Service Bulletins that may apply.
Were there any problems found?
Yes
- Repair as necessary.
- Perform TRANSMISSION VERIFICATION TEST. Refer to 6F24 TRANSMISSION VERIFICATION TEST .
No
- Test Complete.
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.