P2643: Torque Management Feedback Signal B Circuit Low
What to do
The engine drives normally with more cautious gearchanges and traction control. Ask for the receiving module to be disconnected as a test — if the signal recovers, the wiring is sound and the fault is inside that module, which is a very different repair.
What this code means
The second torque feedback circuit reads below its valid range — a short to ground, or an input holding the line down at the receiving end. The mechanism is at P2637 and the unplug-the-receiver test at P2639.
A line pinned low reports minimum torque continuously, which the receiving modules treat as true because it is a plausible value.
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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