Gear Shift Module Communication Circuit Malfunction
The P0860 code indicates a communication failure between the transmission control module (TCM) and the gear shift module (GSM), which may be due to wiring issues, a faulty GSM, or a defective TCM. This can prevent proper gear selection and affect transmission operation.
01. Most Common Causes
- Faulty gear shift module
- Damaged wiring or connectors in the communication circuit
- Defective transmission control module (TCM)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Transmission stuck in one gear or fails to shift
- Inability to shift gears manually
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and check for TCM communication.
Step 2: Inspect wiring and connectors between GSM and TCM for damage or corrosion.
Step 3: Test the gear shift module per manufacturer specifications.
Step 4: If wiring and GSM are okay, test the TCM for proper operation.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
No, driving with this code can lead to unpredictable shifting or transmission damage. It is recommended to have it diagnosed and repaired promptly.
How much does it cost to fix?▼
Diagnosis typically costs $50-$150. Repair costs vary: wiring repair $100-$300, gear shift module replacement $200-$600, TCM replacement $500-$1000.