Variable Induction Control Module: Description and Operation

Throttle Valve Control Module J338

The throttle valve control module contains the following components:

• EPC throttle drive (G186)

• EPC throttle drive angle sensor 1 (G187)

• EPC throttle drive angle sensor 2 (G188)

The Engine Control Module (ECM) actuates the Electronic Power Control (EPC) throttle drive to operate the throttle to regulate the air charge to produce the required engine torque. The two EPC throttle drive angle sensors transmit the current throttle valve position to the ECM.

For safety reasons, the two position sensors have opposite resistance curves and are used for continual self-diagnosis. The ECM always cross checks the signal from both sensors for plausibility.

The throttle valve control module has no serviceable components. If an internal component fails, the complete module must be replaced.

- Faults in the electronic throttle control that will adversely effect emission will also illuminate the Malfunction Indicator Lamp (MIL).

- If a fault occurs in the electronic throttle control system, the appropriate emergency running mode will be activated.

Emergency Running Mode

If the throttle drive motor fails, the throttle valve is automatically moved to the emergency running position. Restricted driving operation at an increased idling speed is possible.

If an angle sensor fails, the second sensor maintains the electronic throttle control function via an emergency running mode. Full engine power is not available.

If both angle sensors fail, the throttle drive is disabled and the engine will only run at an increased idling speed.

Although some earlier versions learned the limits when the key was turned ON, the current versions learn their position when the key is turned OFF.