Shift Solenoid 'A' Control Circuit Low
The P0973 code indicates that the Powertrain Control Module (PCM) has detected a low voltage condition in the control circuit of shift solenoid 'A'. This solenoid is responsible for regulating hydraulic pressure to engage specific gears in the automatic transmission. A low voltage reading suggests a short to ground, open circuit, or faulty solenoid, which can lead to improper transmission operation.
1. Symptoms You Will Notice
- Check Engine Light illuminated
- Harsh or delayed shifting
- Transmission stuck in limp mode or a single gear
- Decreased fuel economy
2. Most Common Causes
- Faulty shift solenoid 'A'
- Short to ground in solenoid control circuit
- Open circuit in wiring or connector
- Damaged PCM (rare)
3. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for additional transmission codes.
Step 2: Inspect the transmission wiring harness and connectors for damage, corrosion, or loose connections.
Step 3: Measure resistance of shift solenoid 'A' (typically 10-30 ohms); compare to specs.
Step 4: Check for voltage at the solenoid connector with the engine running; should see battery voltage.
Step 5: If wiring and solenoid are okay, test the PCM output circuit; replace PCM if necessary.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as the transmission may shift erratically or fail to shift, potentially causing further damage. Limp mode may limit speed.
How much does it cost to fix?▼
Repair costs typically range from $150 to $400, including parts and labor. A solenoid replacement is around $100-$200, plus diagnostic fees.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.