Shift Solenoid 'A' Control Circuit High
The P0974 code indicates that the Powertrain Control Module (PCM) has detected a high 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 high voltage reading typically points to a short to power, a faulty solenoid, or an internal PCM issue. This can cause erratic shifting, transmission slippage, or failure to shift, potentially leading to transmission damage if ignored.
01. Most Common Causes
- Short to power in the wiring or connector of shift solenoid 'A'
- Faulty shift solenoid 'A' (internal short)
- Corroded or damaged connector pins
- Failed PCM (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Harsh or erratic shifting
- Transmission stuck in gear or fails to shift
- Reduced fuel economy
03. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Inspect wiring and connector for damage, corrosion, or shorts to power.
Step 3: Test shift solenoid resistance with a multimeter (typically 20-30 ohms).
Step 4: Check for voltage at solenoid connector with key on (should be battery voltage).
Step 5: If wiring and solenoid are good, test PCM output or replace PCM.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended. Driving with a high voltage condition can cause further transmission damage or sudden loss of gear engagement.
How much does it cost to fix?▼
Repair costs range from $150 to $400, depending on whether the solenoid, wiring, or PCM needs replacement. Labor is typically 1-2 hours.