P0738 – TCM Engine Speed Output Low

Description

The ECM detects a low voltage condition in the TCM engine speed output circuit.

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Symptoms

  • Harsh shifting
  • Limp mode
  • No upshift

Causes

  • Short to ground
  • TCM failure
  • Wiring issues

Diagnosis

  • Monitor TCM output voltage
  • Inspect wiring
  • Check grounds

Repair

  • Repair wiring
  • Replace TCM