Shift Solenoid C Control Circuit Low
The transmission control computer detects that Shift Solenoid C isn't receiving enough electrical power to operate properly. It's like a water valve that needs electricity to open, but the power supply is too weak.
The ECM monitors the voltage and current supplied to Shift Solenoid C during activation. It compares the measured circuit voltage against expected thresholds to detect low voltage conditions that prevent solenoid operation. If voltage drops below the minimum threshold, the fault is logged.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Solenoid Circuit Voltage | 11-14 volts during activation | Below 8 volts or open circuit |
| Solenoid Control Current | 0.5-2.0 amps | Below 0.3 amps or no current draw |
Code P0979 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P0979 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.