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, which can prevent manual mode operation and may cause the transmission to default to automatic mode or a fail-safe state.
01. Most Common Causes
- Faulty manual shift mode switch
- Short to ground in the manual shift mode circuit wiring
- Open circuit or damaged wiring/connectors
- Corroded or loose electrical connections
- Failed PCM (rare)
02. Symptoms You Will Notice
- Inability to shift manually using paddles or shift lever
- Transmission stuck in automatic mode
- Check Engine Light illuminated
- Transmission may enter limp mode or fail-safe mode
- Erratic shifting or harsh engagement
03. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for related codes.
Step 2: Visually inspect the manual shift mode switch and wiring for damage, corrosion, or loose connections.
Step 3: Test the manual shift mode switch resistance and voltage with a multimeter per manufacturer specs.
Step 4: Check for shorts to ground or opens in the circuit between the switch and PCM.
Step 5: If wiring and switch are good, test PCM output signals; replace PCM if necessary.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is generally safe to drive, but manual shift mode will be unavailable. The transmission will operate in automatic mode. However, if the transmission enters limp mode, limit driving and 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 the cause. Replacing a shift mode switch may cost $80-$120, while wiring repairs are usually less.