Gear Shift Module Communication Circuit
What does P0860 mean?
The P0860 code means the vehicle's onboard diagnostic system has detected: Gear Shift Module Communication Circuit. This is a moderate severity code.
Common Symptoms
- Check Engine Light illuminated
- Transmission does not respond to shift lever inputs
- Vehicle may be stuck in Park or current gear
- Multiple transmission-related warning lights
Probable Causes (Ranked by Likelihood)
- Gear shift module communication failure Very High
- CAN bus wiring fault between shift module and TCM High
- Faulty gear shift module Moderate
- TCM CAN bus input failure Low
Step-by-Step Diagnostic Procedure
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Scan for CAN bus communication DTCs in all modules
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Check CAN bus wiring between the shift module and TCM for opens or shorts
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Verify CAN bus termination resistors are within specification
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Test gear shift module power and ground circuits
Frequently Asked Questions
What is a gear shift module?
In vehicles with electronic shifters (shift-by-wire), a gear shift module converts the driver's gear selection into an electronic signal sent to the TCM over the CAN bus network.
Can P0860 leave me stuck in Park?
Yes, if the TCM cannot communicate with the gear shift module, it may not receive the command to exit Park. Some vehicles have a manual park release for emergencies.
Is this common with electronic shifters?
Electronic shift-by-wire systems can develop communication issues over time, especially with connector corrosion or CAN bus wiring problems. They are more complex than traditional cable-operated shifters.