P2544: Transmission torque-request messages fail validity checks

P2544 indicates that the ECM considers a transmission-controller torque request invalid in the reviewed GM strategy. It is a message-content and sequence diagnosis, not a direct measurement of the transmission's actual output torque.

Several different errors can set the same code

The monitor checks message protection, rolling-count progression, requested torque range and rapid changes in intervention type. The documented protection check requires 16 failures out of 20 messages. A rolling-count error or a requested torque increase above 450 Nm uses six errors out of ten. Excessive intervention-type transitions use three failures out of five samples at 200-millisecond intervals.

Those independent paths change what a useful recording needs to contain. A plausible torque-request value does not rule out a protection or sequence error, and a valid message sequence does not prove the requested value stayed within range.

Communication must exist for content to be judged

The source requires no loss of TCM communication associated with U0101. Other prerequisites include run power mode, a running engine, ignition voltage above 6.41 V and run/crank active for more than half a second.

Distinguish a missing message stream from a present stream carrying invalid information. Treating both as the same fault can obscure the monitor's actual evidence.

Verification should confirm valid torque-request messaging under the applicable operating conditions, using appropriate module diagnostic information. The table lists Type B, two-trip behavior but does not prove a mechanical transmission defect or authorize replacement of either controller.

Source and applicability

Confirm the reporting module, system and calibration before applying these diagnostic limits. GM diagnostic table, PDF page 658.