P0955
UniversalThe Automatic Shift Manual (ASM) mode circuit has a performance issue or malfunction related to its input for selecting different driving modes (e.g., Performance, Winter, Sport).
Medium SeverityThis code indicates a problem with the circuit responsible for controlling the Automatic Shift Manual Mode feature, which allows drivers to select different transmission settings like Sport or Winter modes. As a result, the driver may be unable to switch between these specific driving modes, potentially impacting vehicle performance and fuel economy.
⚠️ Before You Begin (Safety First)
Always ensure your vehicle is parked on a level surface with the parking brake engaged before performing any repairs. To prevent electrical shock or damage to the vehicle's systems, disconnect the negative battery terminal before working on electrical components.
Common Symptoms
- Check Engine Light illuminated
- Inability to select different driving modes (Sport, Winter, Performance, etc.)
- Transmission may be stuck in a default driving mode
- Dashboard indicator for driving mode may not change
Common Causes
- Faulty automatic shift manual (ASM) mode select switch
- Damaged or corroded wiring in the ASM mode circuit
- Loose electrical connections to the ASM mode switch or relevant module
- Faulty Transmission Control Module (TCM) or Engine Control Module (ECM) (less common)
- Blown fuse related to the ASM mode circuit
Frequently reported on: General/Universal
Diagnostic Steps
- Visually inspect the ASM mode selection switch for any physical damage or stuck buttons.
- Check all fuses related to the transmission control and dashboard functions. Refer to your vehicle's owner's manual for fuse box locations and diagrams.
- Inspect the wiring harness and connectors leading to the ASM mode switch and the Transmission Control Module (TCM) for signs of damage, corrosion, or loose connections.
- If accessible, test the continuity and resistance of the ASM mode switch using a multimeter (refer to service manual specifications).
- Clear the code and retest the system to see if the issue reappears.
👨🔧 When to Call a Professional
If after checking basic wiring and the mode selection switch, the issue persists, or if you are uncomfortable with electrical diagnostics, it is best to consult a professional mechanic. Advanced electrical testing may be required to pinpoint the exact fault.
Commonly Asked Questions
What does the P0955 code specifically mean?
P0955 indicates a fault in the circuit that controls the Automatic Shift Manual (ASM) mode, which allows you to switch between various driving modes like Sport or Winter.
Is it safe to drive my car with a P0955 code?
While it might not be a critical safety issue, your vehicle may be stuck in a default driving mode, affecting performance or fuel economy. It's recommended to address it promptly.
What is the most common cause of a P0955 code?
The most common causes are usually a faulty automatic shift manual mode select switch or issues with its wiring and connectors.
Can I fix the P0955 code myself?
Yes, many DIYers can fix this by checking fuses, inspecting wiring, and potentially replacing the mode select switch, depending on their comfort with electrical work.
How does the ASM mode affect my driving?
The ASM mode allows you to manually select gears or choose different transmission characteristics (e.g., sportier shifts, better traction in winter). A fault means you lose this control.