Auto Shift Manual Mode Circuit Malfunction
The P0955 code indicates a problem in the manual mode shift circuit of an automatic transmission. This circuit allows the driver to manually select gears. The Powertrain Control Module (PCM) detects an abnormal voltage or resistance in the circuit, often due to a faulty shift switch, wiring issues, or a malfunctioning transmission control module.
1. Symptoms You Will Notice
- Inability to shift manually using the shift lever or paddles
- Transmission stuck in automatic mode
- Check Engine Light illuminated
- Erratic shifting or limp mode
2. Most Common Causes
- Faulty manual mode shift switch
- Damaged wiring or connectors in the shift circuit
- Malfunctioning transmission control module (TCM)
- Corrosion or loose connections
3. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for related codes.
Step 2: Inspect the manual mode shift switch and its wiring for damage or corrosion.
Step 3: Test the switch and circuit continuity with a multimeter.
Step 4: Check the TCM for proper operation and update software if needed.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is generally safe to drive, but you may lose manual shift capability. If the transmission enters limp mode, drive cautiously to a repair shop.
How much does it cost to fix?▼
Repair costs range from $150 to $400, depending on the cause. A switch replacement is cheaper, while TCM repair or replacement is more expensive.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.