Shift Solenoid A Control Circuit High
The transmission control computer detects that Shift Solenoid A is receiving too much electrical voltage, like a light switch stuck in the 'on' position. This prevents the solenoid from properly controlling gear shifts.
The ECM monitors the control voltage sent to Shift Solenoid A through its dedicated circuit. It expects a specific voltage pattern to activate and deactivate the solenoid for smooth shifting. When the voltage stays abnormally high or doesn't drop as expected, the ECM logs this fault.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Solenoid Control Voltage | 0V to 12V (pulsed PWM signal) | Voltage remains above normal threshold or fails to modulate properly |
| Circuit Resistance | 4-14 ohms | Below 4 ohms (short to power) |
Code P0974 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, P0974 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.