P0865

TCM Communication Circuit Low

Severity

⚠️ Medium

Can you drive?

Limited driving only, diagnose soon

Approx. repair cost

$56–167 (est.)

Symptoms

Incorrect gear shifting
Transmission transition to emergency mode
Check Engine Light Illuminates
Reduced engine power
Problems with cruise control

Causes

Open or short circuit in the TCM communication circuit
Bad contacts in connectors
TCM module malfunction
Problems with power supply or grounding of the TCM module
Malfunction of other related modules (e.g. engine ECU)

How to Fix

Check the integrity of the TCM communication circuit
Inspect and clean the contacts in the connectors
Check the power supply and grounding of the TCM module
Scan other modules for errors
If necessary, replace the TCM module

Related codes

P0866 P0867 P0868