OBD II Fault Code

  • OBD II P0634

OBD-II Code Transmission Control Module (TCM) failure is defined as a PCM/ECM/TCM Internal Temperature "A" Too High

Some vehicles place the Transmission Control Module (TCM) inside the Transmission. Due to the potential for heat buildup inside the transmission, the TCM is equipped with its own temperature sensor. If the TCM detects that it is getting too hot, it will set P0634. It will also place the vehicle into "Limp Home Mode", limiting the amount of power available, to prevent further damage.

Transmission Control Module (TCM) failure Symptoms

  • Engine may enter limp home mode (reduced performance)

Common Problems That Trigger the P0634 Code

  • Damaged transmission cooler
  • Internal transmission failure
  • Transmission Control Module (TCM) failure
  • Wiring issue
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