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 (IPC) 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 speed 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 both TP sensor inputs, loss of throttle plate control, stuck throttle plate, significant processor concerns, or other major electronic throttle body concern. 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 speed control is disabled. |
| Shutdown | If a significant processor concern is detected, the monitor forces the vehicle to shutdown by disabling engine, generator and traction motor. The powertrain malfunction indicator (wrench), MIL, and hazard indicator may illuminate. |
Electronic Throttle Monitor Operation
| DTCs (1) | Description (Indicator Lamp) | ||
|---|---|---|---|
| P060X, P061X | PCM processor concern (MIL, powertrain malfunction indicator [wrench]) | ||
| U0300 | ETC software version mismatch between processors internal to the PCM (MIL, powertrain malfunction indicator [wrench], hazard light, and vehicle shutdown) | ||
|
|||