P0950
UniversalASM Control Circuit [Up / Down / Auto / etc]
Low SeverityThe P0950 code indicates a fault in the Automatic Shift Manual (ASM) control circuit, which manages the manual gear selection mode in an automatic transmission. This typically means the driver will be unable to manually select gears using the shifter's +/- or paddle shifters, though the vehicle's fully automatic mode often remains operational.
⚠️ Before You Begin (Safety First)
Always exercise caution when working on vehicle electrical systems. Ensure the ignition is off and disconnect the battery's negative terminal before inspecting or repairing wiring and components to prevent electrical shock or damage to the vehicle's computer systems. Be aware of hot engine components and moving parts.
Common Symptoms
- Check Engine Light illuminated
- Inability to shift gears manually (e.g., using +/- or paddle shifters)
- Transmission stuck in automatic mode
Common Causes
- Faulty ASM control switch (shifter or paddle shifter)
- Open or short circuit in the ASM control wiring
- Corroded or loose electrical connections to the ASM switch or transmission control module (TCM)
- Failed Transmission Control Module (TCM) (less common)
Frequently reported on: General/Universal
Diagnostic Steps
- Connect an OBD-II scanner to confirm P0950 and check for other related codes. Clear the code and test drive to see if it returns.
2. Visually inspect the wiring and connectors associated with the shifter assembly and any paddle shifters for damage, corrosion, or loose connections.
3. Using a multimeter, test the continuity and resistance of the ASM control switch circuit according to your vehicle's service manual specifications.
4. If accessible, inspect the TCM connectors for signs of corrosion or damage.
5. If a specific switch is found to be faulty, consider replacing the switch or the entire shifter assembly if the switch is integrated.
👨🔧 When to Call a Professional
If you lack experience with electrical diagnosis or if the automatic transmission mode also begins to malfunction, it is best to consult a professional automotive technician immediately to prevent further transmission damage.
Commonly Asked Questions
Can I still drive with a P0950 code?
Yes, in most cases, you can still drive your vehicle as the fully automatic transmission mode typically remains functional. However, you will lose the ability to manually select gears.
What is the <strong>Automatic Shift Manual (ASM) control circuit</strong>?
It's the electrical system responsible for allowing you to manually shift gears (up or down) in a vehicle equipped with an automatic transmission that has a manual shift mode (often called tiptronic, sport shift, etc.).
Is it expensive to fix a P0950 code?
The cost varies greatly depending on the cause. A simple wiring repair might be inexpensive, while replacing a complex shifter assembly or a Transmission Control Module (TCM) could be costly.
How do I test the ASM control switch?
You'll typically need a multimeter and your vehicle's wiring diagrams. You would test for continuity and resistance across the switch terminals in different gear positions to ensure it's sending the correct signals to the TCM.
Can a low battery cause a P0950 code?
While a severely low battery can cause various electrical gremlins and false codes, it's less likely to directly cause a P0950 unless it's impacting the TCM's ability to communicate or receive proper voltage for the shifter circuit. It's always good to ensure your battery is in good health.