TAC System Default Actions/Limp Home

There are two limp home modes that the ECM can default to if an error is detected in the TAC system. If an APP sensor 1 or sensor 2 circuit fault, TP sensor 2 circuit fault OR if a TP sensor 1 circuit fault is detected with some APP angle, the ECM will go into one of the two limp home modes. In this mode, the maximum accelerator pedal angle value is set to 10% and the rate at which the rise in pedal angle is severely slowed. The ECM will remain in this limp home mode during the entire ignition cycle even if the fault is corrected.

If a throttle actuator circuit fault, throttle actuator command vs. actual position fault, return spring check fault or a TP sensor 1 circuit fault (below 50 mph with no accelerator pedal angle) occurs, the ECM will go into the other limp home mode. In this mode, the engine speed is limited to 2600 rpm and the # 3 through # 6 fuel injectors are randomly turned Off. At this time the REDUCED POWER telltale will be commanded On. The ECM will remain in this limp home mode during the entire ignition cycle even if the fault is corrected.

IMPORTANT: If a TP sensor 1 or throttle actuator circuit fault is present at the time the vehicle is an idle, with no accelerator pedal angle, the engine may stall.