P0978 code indicates an issue with the performance or range of the Shift Solenoid “C” control circuit in a vehicle’s transmission system.
P0978 Shift Solenoid “C” Control Circuit Range/Performance
Code symptoms P0978.
– Delayed or rough shifting
– Harsh shifting between gears
– Slipping transmission
– Illuminated check engine light
Causes of the code P0978.
1. Faulty shift solenoid “C”: The shift solenoid itself may be defective and not operating properly, causing the circuit to perform out of range or with poor performance.
2. Wiring issues: Problems with the wiring harness such as breaks, frays, or corrosion can interfere with the signal transmission between the shift solenoid and the vehicle’s control module.
3. Poor electrical connections: Loose or poor connections at the shift solenoid or control module can lead to erratic performance of the circuit, triggering the trouble code.
4. Low transmission fluid level: Inadequate transmission fluid can affect the proper functioning of the shift solenoid, causing range or performance issues in the control circuit.
5. Internal transmission problems: Issues within the transmission itself, such as mechanical failures or fluid contamination, can also contribute to the P0978 trouble code.
Code Solutions P0978.
1. Check the wiring and connectors associated with the shift solenoid “C” for any signs of damage or corrosion. Repair or replace as needed.
2. Test the shift solenoid “C” to ensure it is functioning correctly. Replace the solenoid if it is faulty.
3. Inspect the transmission fluid level and condition. Top up or replace the fluid if necessary.
4. Reset the onboard computer by disconnecting the vehicle’s battery for a few minutes. Reconnect and check if the trouble code reoccurs.
5. Perform a thorough diagnostic scan using a professional scan tool to identify any other potential issues within the transmission system.