P0865 – TCM Communication Circuit

Description

The ECM detects a malfunction in the TCM communication circuit.

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Symptoms

  • Harsh shifting
  • Limp mode
  • Multiple warning lights

Causes

  • CAN wiring fault
  • Loose connectors
  • TCM failure

Diagnosis

  • Scan for U-codes
  • Inspect CAN wiring
  • Check module power

Repair

  • Repair wiring
  • Clean connectors
  • Replace TCM