Shift Solenoid "A" Control Circuit Low
The P0973 code indicates that the Powertrain Control Module (PCM) or Transmission Control Module (TCM) has detected a low voltage condition in the control circuit for shift solenoid 'A'. This typically means the circuit is shorted to ground, preventing the solenoid from properly directing transmission fluid pressure to execute gear shifts.
This code is urgent because a malfunctioning shift solenoid can cause erratic shifting, transmission slipping, or force the vehicle into limp mode. Continued driving can lead to internal transmission damage or leave you stranded.
Common symptoms
- Check Engine Light illuminated
- Harsh, delayed, or erratic gear shifts
- Transmission slipping between gears
- Vehicle stuck in a specific gear (limp mode)
- Decreased fuel economy due to inefficient shifting
Likely causes
- Defective shift solenoid 'A'
- Short to ground or damaged wiring in the shift solenoid 'A' circuit
- Corroded or damaged connectors at the transmission or PCM/TCM
- Dirty or contaminated transmission fluid causing solenoid mechanical failure
- Faulty Transmission Control Module (TCM) or Powertrain Control Module (PCM)
What to check before replacing parts
Check the transmission fluid level and condition.
Look for: Low fluid levels or burnt, heavily contaminated fluid that could cause the solenoid to stick or fail.
Visually inspect the wiring harness and connectors for the transmission and shift solenoid 'A'.
Look for: Frayed wires, melted insulation, or corroded pins that could cause a short to ground in the control circuit.
Measure the internal resistance of shift solenoid 'A' using a digital multimeter.
Look for: Resistance readings that fall outside the manufacturer's specified range, indicating an internal short or failure within the solenoid itself.
Test the control circuit wiring for continuity and shorts to ground between the TCM/PCM and the transmission connector.
Look for: Continuity to ground on the control wire when disconnected at both ends, which confirms a short to ground in the harness.
Command shift solenoid 'A' ON and OFF using a bidirectional scan tool.
Look for: A lack of an audible click from the transmission pan or no change in live transmission pressure data, confirming the solenoid is unresponsive.
This page explains the generic P0973 definition and is general reference information, not a diagnosis for your specific vehicle. Actual causes, severity, and repairs vary by make, model, engine, and mileage — always confirm with a scan tool and a qualified technician before replacing parts.
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