Electronic Throttle Control (ETC) System Strategy

The torque based ETC strategy was developed to improve fuel economy and to accommodate variable camshaft timing (VCT). This is possible by not coupling the throttle angle to the driver pedal position. Uncoupling the throttle angle (produce engine torque) from the pedal position (driver demand) allows the powertrain control strategy to optimize the fuel control while delivering the requested torque.

The ETC monitor system is distributed across two processors within the PCM: the main powertrain control processor unit (CPU) and a separate monitoring processor. The primary monitoring function is carried out by the independent plausibility check software, which resides on the main processor. It is responsible for determining the driver demanded torque and comparing it to an estimate of the actual torque delivered. If the generated torque exceeds driver demand by a specified amount, appropriate corrective action is taken.

ETC SYSTEM FAILURE MODE EFFECTS MANAGEMENT (FMEM)

Effect	Failure Mode
No Effect On Driveability	A loss of redundancy or loss of a non critical input could result in a concern that does not affect driveability. The powertrain malfunction indicator (wrench) and the malfunction indicator lamp (MIL) do not illuminate, however the cruise control may be disabled. A DTC is set to indicate the component or circuit with the concern.
Delayed APP Sensor Response With Brake Override	This mode is caused by the loss of one APP sensor input due to sensor, wiring, or PCM concerns. The system is unable to verify the APP sensor input and driver demand. The throttle plate response to the APP sensor input is delayed as the accelerator pedal is applied. The engine returns to idle RPM whenever the brake pedal is applied. The powertrain malfunction indicator (wrench) illuminates, but the MIL does not illuminate in this mode. An APP sensor related DTC is set.
LOS Supercreep	This mode is caused by the loss of both APP sensor inputs, internal control mode torque performance, generator speed, crankshaft position (CKP) sensor concerns or other PCM concerns. There is no response when the accelerator pedal is applied, however, when the brake pedal is released, the vehicle will accelerate in a controlled manner up to a maximum vehicle speed of 56 km/h (35 MPH) on a flat surface. The PCM will automatically adjust the torque delivered based on a calibrated torque speed curve. The driver can override this torque by either applying the brake pedal or moving the gear selector to NEUTRAL. The powertrain malfunction indicator (wrench) illuminates, but the MIL does not illuminate in this mode. An internal control module torque performance DTC, internal control module drive motor DTC, generator DTC, engine speed sensor DTC or APP sensor DTC is set.
LOS Creep Mode	Creep mode is caused by the loss of one brake pedal position (BPP) and one APP sensor input. The system is unable to determine driver demand. There is no response when the accelerator pedal is applied. The powertrain malfunction indicator (wrench) illuminates, but the MIL does not illuminate in this mode. An APP and BPP sensor, or harness related DTC is set.
RPM Guard With Default Throttle	In this mode, the throttle plate control is disabled due to the loss of throttle position, the throttle plate position controller, or other major electronic throttle body concern. Depending on the concern detected, the throttle plate is either commanded to the default (limp home) position or the motor is disabled and the spring returns the throttle plate to the default (limp home) position. A maximum allowed RPM is determined based on the position of the accelerator pedal (RPM Guard). If the actual RPM exceeds this limit, spark and fuel are used to bring the RPM below the limit. The powertrain malfunction indicator (wrench) and the MIL illuminate in this mode and a DTC for an ETC related component is set. EGR and VCT outputs are set to default values and cruise control is disabled.
Shutdown	If a significant processor concern is detected, the monitor forces the vehicle to shutdown by disabling the engine, the generator and the traction motor. The powertrain malfunction indicator (wrench), MIL, and hazard indicator may illuminate.
Accelerator Pedal Position (APP) Sensor Check	Correlation and range/performance sensor disagreement between processors internal to the PCM. Monitor execution is continuous. Monitor false detection duration is less than 1 second to register a concern. Refer to DIAGNOSTIC TROUBLE CODE (DTC) CHARTS AND DESCRIPTIONS for additional DTC information. The powertrain malfunction indicator (wrench) illuminates, the MIL does not illuminate in this mode.
Throttle Position (TP) Sensor Check	Correlation and range/performance sensor disagreement between processors internal to the PCM, TP inconsistent with requested throttle plate position. Monitor execution is continuous. Monitor false detection duration is less than 1 second to register a concern. Refer to DIAGNOSTIC TROUBLE CODE (DTC) CHARTS AND DESCRIPTIONS for additional DTC information. The powertrain malfunction indicator (wrench) illuminates, the MIL may illuminate in this mode.