P0738: Transmission Control Module Engine Speed Output Circuit Low
What to do
Usually no effect on how the vehicle drives. The rev counter may read zero or sit low.
What this code means
The engine speed output from the transmission module is stuck low, normally a short to ground on the output wire. Because the module monitors what it drives, it can tell the difference between commanding a signal and that signal actually appearing — which is what produces this code rather than silence.
Likely causes
Start here
- Wiring shorted to ground · moderate
- Corroded or loose connector · easy
Less common
- Faulty transmission control module · specialist
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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