P2546 indicates that the powertrain control module (PCM) is receiving a torque management request input signal from another control module (commonly the transmission control module, ABS/ESC module, or body control module) that is below the expected voltage or data range. The PCM uses this input to coordinate engine torque reduction for transmission shifts, traction/stability events, or cruise control functions. Setting the code means the requesting signal has fallen out of the acceptable parameter window, which can affect torque delivery and shift scheduling.
Open circuits, chafed wires, water ingress, or poor pin contact are the most common cause of a low signal on any input to the PCM. Inspect the harness between the sending module and the PCM carefully.
If the requesting signal originates from a discrete sensor (such as a brake-pressure or pedal-position sensor used for torque management), internal failure of that sensor can pull the voltage low.
Loss of data from the sending module, excessive bus resistance, or a short to ground on the signal wire can all cause the PCM to see a low or missing request.
If the module that originates the torque request has an internal fault or power/ground issue, it may output an out-of-range signal to the PCM.
Voltage drops under load or corroded ground straps can drag a 5-volt reference or signal line below its expected threshold and trigger the code.
Rare. The PCM itself can fail internally or require a reflash, but this is among the least common causes and should only be considered after wiring, sensors, grounds, and the sending module have all been ruled out.
Short trips to a repair facility are usually fine, but the vehicle may enter reduced-power mode, shift harshly, or behave unpredictably if the underlying fault is related to a brake or stability control input. Have it diagnosed promptly.
No. In the vast majority of cases P2546 is caused by wiring, connectors, a sensor, or the module that sends the torque request — not the PCM itself. Replacing the PCM without first verifying the input circuit is a common and expensive mistake.
Yes, if the underlying issue is intermittent (a loose connector or momentary voltage drop) the code may set and then clear. However, the underlying fault usually returns and should be investigated, because intermittent torque-management faults can cause drivability or safety issues.
Generally no. P2546 points to a specific input circuit or the module generating the torque request. Repairs not directed at that circuit or module will not resolve the code.