P2637 means the engine or powertrain control module has detected an unexpected, missing, or out-of-range feedback signal on the torque-management circuit. This signal is used to confirm that a torque-reduction request—often sent during shifting, traction control, or other driveline events—was received and acted upon.
Open, shorted, corroded, or damaged wiring and pins in the torque-management feedback signal path are the most common cause. Intermittent connections can produce the same fault.
Outdated control-module calibration can cause false or persistent torque-management feedback faults. A reflash or module programming update often resolves this.
The transmission control module or another module that requests or confirms torque reduction may fail to send or receive the feedback signal correctly.
A failed PCM or ECM is possible but uncommon for this code. It should only be considered after wiring, connectors, software, and related modules have been ruled out.
Short trips are usually possible, but the vehicle may enter reduced-power or limp mode and shift quality may suffer. It is best to diagnose it promptly to avoid further driveline stress.
Usually no. The PCM is rarely the actual cause. Most instances are due to wiring, connector, or software issues, or a related control module fault.
The engine control module, transmission control module, traction control, and stability control systems can all be involved because they share torque-reduction requests.
Yes, in many cases an updated control-module calibration or reflash corrects erroneous torque-management feedback faults.