Transmission

P0974 — Shift Solenoid A Control Circuit High

Severity: medium Drive with care, to a shop

What P0974 means

The transmission control unit (TCM or PCM) switches shift solenoid A on and off to control gear changes, and it monitors the voltage in that circuit. P0974 sets when the voltage is higher than expected, which points to an open circuit, a short to power or a failing driver in the module. As a result, shifts may become incorrect.

Symptoms

  • Check Engine light on
  • Missed or delayed shifts
  • Harsh or jerky gear changes
  • Transmission stuck in one gear (limp mode)
  • Worse fuel economy
  • No overdrive engagement

Possible causes

  1. Open circuit or poor connection in the solenoid wiring
  2. Failed shift solenoid A (open winding)
  3. Damaged wiring harness or connector at the transmission
  4. Control wire shorted to battery positive
  5. Corroded or pushed-out connector terminals
  6. Faulty TCM/PCM (solenoid driver)

How to diagnose

  1. Scan all codes and freeze frame data and note any other transmission codes.
  2. Check transmission fluid level and condition.
  3. Inspect the harness and transmission connector for chafing, corrosion, oil intrusion and bent pins.
  4. Measure the resistance of solenoid A and compare it with the spec for your vehicle.
  5. Test the wire from the module to the solenoid for opens and shorts to power or ground.
  6. Command the solenoid with a scan tool and verify voltage and signal at the connector.
  7. If the wiring and solenoid are good, test the control module and reprogram or replace it as needed.

Common fixes

  • Repair or replace the damaged section of wiring
  • Clean or replace the transmission connector
  • Replace shift solenoid A (or the solenoid pack)
  • Change dirty fluid and filter
  • Reprogram or replace the TCM/PCM

Questions and answers

What does P0974 mean?

The transmission control unit detected high voltage in the shift solenoid A circuit. The usual causes are an open wire, a short to power or a bad solenoid.

Can I drive with P0974?

Only briefly and carefully, for example to a repair shop. The transmission may enter limp mode, and continued driving raises the risk of internal damage.

How much does it cost to fix P0974?

It depends on the cause. A connector or wire repair is usually cheaper than a new solenoid, and a control module is typically the most expensive. Only a proper diagnosis will tell.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.