Gear Shift Module Communication Circuit Failure
The P0860 code indicates a communication failure between the transmission control module (TCM) and the gear shift module (GSM), which may be due to a faulty GSM, wiring issues, or a TCM problem. This can prevent the vehicle from shifting properly or recognizing the selected gear.
1. Symptoms You Will Notice
- Check Engine Light illuminated
- Transmission stuck in one gear or fails to shift
- No response when shifting gears
- Erratic or delayed shifting
2. Most Common Causes
- Faulty gear shift module
- Damaged wiring or connectors in the communication circuit
- Failed transmission control module (TCM)
3. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm P0860 and check for related codes.
Step 2: Inspect the gear shift module and its wiring for damage, corrosion, or loose connections.
Step 3: Test communication between TCM and GSM using a multimeter or oscilloscope.
Step 4: If wiring is intact, replace the gear shift module and clear codes.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
No, driving with P0860 can cause unpredictable shifting or loss of gear selection, leading to unsafe driving conditions. Have it diagnosed and repaired promptly.
How much does it cost to fix?▼
Diagnosis typically costs $50-$150. Replacing the gear shift module can range from $200-$500 including parts and labor, depending on the vehicle.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.