P2639: Torque Management Feedback Signal A Circuit Low
What to do
The engine drives normally; the gearchanges and the traction control behave more cautiously. The quick test worth asking for is to unplug the module at the receiving end and see whether the signal returns to normal — that separates a shorted wire from a failed module input in minutes and decides which of two very different repairs is needed.
What this code means
The torque feedback circuit reads below its valid range — a short to ground, or an input at the receiving end holding the line down.
A signal pinned to the bottom of its range reports minimum torque continuously, which is a plausible value and is therefore acted upon: the effects are P2638's, in their most consistent form.
As with the signal output codes at P2615, an input that has failed inside the receiving module does this to a shared line and is indistinguishable from a shorted wire from the transmitting end. Disconnecting the receiving module and watching whether the line recovers separates the two in a couple of minutes, and decides between a wiring repair and a module.
Likely causes
Start here
- Wiring shorted to ground · moderate
- Faulty receiving module input · specialist
- Damaged wiring harness · moderate
Less common
- Corroded or loose connector · easy
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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