P0737: TCM Engine Speed Output Circuit

What does P0737 mean?

Some transmission modules pass an engine speed signal on to other devices such as a tachometer over a wire of their own. CARB requires output circuits to be checked. No manufacturer document available to us uses P0737–P0739 – engine speed is shared over CAN today; the description follows CARB and the engine module's own speed output (P0654), which sends, for example, two pulses per revolution. P0737 is the general circuit fault of this output; low and high are P0738/P0739. Not to be confused with the engine speed input at the transmission module (P0725 ff). A tachometer or dependent display then reads wrong or nothing, while driving is usually unaffected.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

• Tachometer or dependent display not working or wrong
• Warning lamp depending on manufacturer
• Usually no effect on driving

Common causes

• High Wire to the receiver open or shorted
• Medium Receiver (e.g. instrument cluster) shorted internally
• Medium Connector corroded
• Low Driver stage in the transmission module faulty

Likelihood is a general estimate across vehicles; your make and model may differ.