P0958
UniversalAutomatic Shift Manual (ASM) Mode Circuit High
Medium SeverityThe Powertrain Control Module (PCM) or Transmission Control Module (TCM) has detected a voltage signal higher than expected in the circuit for the Automated Shift Manual (ASM) Mode. This typically means there's an electrical fault preventing the transmission's manual shift function from operating correctly.
⚠️ Before You Begin (Safety First)
Always practice caution when working on vehicles. Ensure the vehicle is safely supported on jack stands if working underneath. Always disconnect the battery's negative terminal before performing electrical work to prevent accidental shorts or shocks. Wear appropriate eye protection.
Common Symptoms
- Check Engine Light illuminated
- Inability to manually shift gears (e.g., using paddle shifters or console shifter)
- Transmission stuck in 'D' or default automatic mode
- Erratic shifting in automatic mode (less common)
Common Causes
- Faulty ASM mode switch or sensor
- Short to voltage in the ASM mode circuit wiring
- Corroded or loose electrical connectors
- Faulty Transmission Control Module (TCM) or Powertrain Control Module (PCM)
Frequently reported on: General/Universal
Diagnostic Steps
- Inspect the wiring and connectors related to the ASM mode switch for any visible damage, corrosion, or looseness.
- Using a multimeter, test the voltage at the ASM mode switch circuit to confirm a high voltage reading.
- Check the continuity of the circuit wiring for any shorts to power.
- If the wiring and connections appear sound, consider testing or replacing the ASM mode switch/sensor.
- If all external components check out, a professional diagnosis for a potential internal TCM/PCM fault may be necessary.
👨🔧 When to Call a Professional
If you are not comfortable performing electrical diagnostic work or if the problem persists after checking basic components, it is best to consult a professional technician. Complex wiring issues or an internal transmission control module fault will require specialized diagnostic tools.
Commonly Asked Questions
Can I drive with a P0958 code?
Yes, typically you can still drive your vehicle with a P0958 code, but you will likely lose the ability to manually shift gears. The automatic transmission should still function.
What is 'ASM Mode'?
ASM Mode, or Automatic Shift Manual Mode, refers to a feature in some automatic transmissions that allows the driver to manually select gears, often using paddle shifters on the steering wheel or a specific shift gate on the console.
Is a P0958 repair expensive?
The cost of repair varies. If it's a simple faulty switch or a damaged wire, it could be relatively inexpensive. If the Transmission Control Module (TCM) is at fault, the repair can be significantly more costly.
How do I clear the P0958 code?
You can clear the P0958 code using an OBD-II scanner. However, clearing the code without fixing the underlying issue will only cause the Check Engine Light to return after a short period of driving.
Does this code affect automatic shifting?
While P0958 primarily impacts the manual shift function, in some rare cases or if the fault is severe, it could potentially cause erratic behavior in automatic shifting, though this is not its primary symptom.