What it means
The control module detects a high electrical level in the shift solenoid A control circuit.
At a glance
- Usually lights the check-engine light
How it works
Shift solenoid A is an electrically operated valve that directs fluid for transmission gear changes. The control module monitors the A control circuit and sets P0974 when its electrical level is higher than expected. A short to battery power can hold the circuit high and prevent the module from controlling the solenoid as intended.
Common causes
Most likely first.
- Short to battery
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
How to diagnose it
- Save freeze-frame data and review live transmission data to identify when the solenoid A circuit went high.
- Inspect solenoid A wiring for pinching or contact with a battery-positive supply, particularly near harness bends and connectors.
- Check the solenoid A connector for corrosion, spread terminals, or incorrect connections that could affect the circuit reading.
- Use the vehicle wiring diagram to test the control circuit for a short to battery voltage and inspect for insulation damage.
- Test solenoid A and its circuit against the manufacturer’s specification to distinguish a component fault from a wiring fault.
- Assess the transmission control module only after the circuit has been isolated from shorts and the solenoid has passed testing.
Common fixes
- Repair a pinched wire or damaged insulation allowing the solenoid A circuit to contact battery power.
- Repair corroded, loose, or damaged terminals at the solenoid A connector.
- Replace shift solenoid A if it fails the specified test.
- Repair or replace the transmission control module if testing verifies an internal control fault.
Can I keep driving?
If shifting becomes harsh, delayed, or unreliable, avoid high loads and long journeys, and stop driving if the transmission slips or loses drive. A circuit stuck high can interfere with gear changes and continued abnormal operation can cause further wear.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.