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 harsh shifting, gear slippage, or transmission stuck in a single gear.
1. Symptoms You Will Notice
- Check Engine Light illuminated
- Harsh or erratic shifting
- Transmission stuck in gear or limp mode
- Decreased fuel economy
2. Most Common Causes
- Short to power in the wiring harness or connector
- Faulty shift solenoid 'A'
- Corroded or damaged connector pins
- Internal PCM failure
3. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Visually inspect wiring and connectors for damage, corrosion, or shorts.
Step 3: Test 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, suspect PCM failure.
4. 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 leave you stranded. Limp mode may limit speed.
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.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.