Auto Shift Manual Mode Circuit Low
The P0957 code indicates that the Powertrain Control Module (PCM) has detected a low voltage condition in the manual shift mode circuit of an automatic transmission. This circuit allows the driver to manually select gears via the shift lever or paddles. A low voltage reading suggests a short to ground, open circuit, or faulty component in the manual shift mode switch or wiring.
1. Symptoms You Will Notice
- Check Engine Light illuminated
- Inability to manually shift gears
- Transmission stuck in automatic mode
- Harsh or erratic shifting
- Reduced fuel economy
2. Most Common Causes
- Faulty manual shift mode switch
- Short to ground in the manual shift mode circuit wiring
- Open circuit in the manual shift mode circuit
- Corroded or damaged connector at the shift lever or PCM
- Failed PCM (rare)
3. Step-by-Step Diagnosis
Step 1: Scan for additional codes and record freeze frame data.
Step 2: Visually inspect the shift lever assembly and wiring for damage or corrosion.
Step 3: Test the manual shift mode switch resistance and compare to specifications.
Step 4: Check for voltage and ground at the switch connector using a multimeter.
Step 5: If wiring and switch are okay, test the PCM input/output for the manual shift circuit.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is generally safe to drive, but you will lose manual shift capability. The transmission will operate in automatic mode. However, if shifting becomes erratic, have it inspected promptly.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for diagnosis and repair, depending on whether the switch or wiring needs replacement. Parts are usually inexpensive.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.