Transmission

P0973 — Shift Solenoid A Control Circuit Low

Severity: medium Drive with care, to a shop

What P0973 means

The transmission control module (TCM) operates shift solenoid A by switching its circuit, which directs hydraulic pressure to the valves that select gears. P0973 sets when the voltage in this control circuit is lower than expected, which points to a short to ground or abnormal resistance. The usual culprits are damaged wiring, a failed solenoid or, less often, the control module itself.

Symptoms

  • Check Engine or transmission warning light on
  • Transmission in limp mode, stuck in one gear
  • Problems or harsh engagement in first gear
  • Harsh, delayed or missing shifts
  • Poor acceleration and worse fuel economy

Possible causes

  1. Chafed wiring shorted to ground in the solenoid circuit
  2. Failed shift solenoid A with a shorted coil
  3. Corroded or damaged connector at the transmission
  4. Transmission fluid or moisture contaminating the connector or internal harness
  5. Faulty TCM or PCM
  6. Dirty or degraded fluid and debris affecting the solenoid

How to diagnose

  1. Scan all codes and freeze-frame data, note any other solenoid codes, then clear and see if P0973 returns
  2. Check transmission fluid level and condition: color, smell, debris
  3. Inspect the harness and transmission connector for chafing, oil intrusion and corrosion
  4. Measure solenoid A coil resistance and compare with the manufacturer spec
  5. Test the control wire for a short to ground with the TCM connector unplugged
  6. Verify power and ground supply at the TCM
  7. Run a scan tool solenoid actuation test if supported
  8. If wiring and solenoid check out, test or reprogram the TCM

Common fixes

  • Repair or replace the damaged section of wiring
  • Replace shift solenoid A or the solenoid pack
  • Clean or replace the connector and terminals
  • Change transmission fluid and filter if contaminated
  • Replace or reflash the TCM once confirmed faulty

Questions and answers

What does P0973 mean?

It means the transmission control module detected low voltage in the shift solenoid A control circuit. This is usually a short to ground in the wiring or a failed solenoid.

Can I drive with P0973?

Only carefully and for a short distance, such as to a repair shop, because the transmission is likely in limp mode. Extended driving can damage the transmission.

How do I fix P0973?

Start with the fluid, wiring and connector, then test the solenoid resistance. Most often the fix is wiring repair or a new solenoid, and only occasionally a new TCM.

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.