Electronic Throttle Control Indicator

The Electronic Throttle Control (ETC) indicator gives an indication to the vehicle operator when the ETC system, or a circuit or component of the system is ineffective. The ETC indicator is controlled by a transistor on the IC circuit board based upon programming and electronic messages received by the IC from the PCM over the CAN data bus. The IC will illuminate the ETC indicator for about fifteen seconds as a bulb test each time the ignition switch status transitions to ON.

The ETC indicator LED is completely controlled by the IC logic circuit, and that logic will only allow this indicator to operate when the IC receives a battery current input on the fused ignition output (run-start) circuit. Therefore, the LED will always be OFF when the ignition switch status is anything except ON or START. The LED only illuminates when it is provided a path to ground by the IC transistor. The IC will turn ON the ETC indicator for the following reasons:

• ETC Indicator Lamp-On Message  - Each time the IC receives an electronic ETC indicator lamp-ON  message from the PCM, the ETC indicator will be illuminated. The indicator can be flashed ON and OFF, or illuminated solid, as dictated by the PCM message. The indicator remains illuminated solid or continues to flash for about 12 seconds or until the IC receives a lamp-OFF message from the PCM, whichever is longer. If the indicator is illuminated solid with the engine running the vehicle will usually remain drivable. If the indicator is flashing with the engine running the vehicle may require towing. A flashing indicator means the ETC system requires immediate service. The indicator will be extinguished when the ignition switch status transitions to OFF.

The PCM continually monitors the ETC system circuits and sensors to decide whether the system is in good operating condition. The PCM then sends the proper lamp-ON or lamp-OFF message to the IC. If the PCM sends a lamp-ON message after the bulb test, it indicates that the PCM has detected an ETC system malfunction or that the ETC system is ineffective. The PCM will store a DTC for any malfunction it detects. Each time the ETC indicator fails to illuminate due to an open or short in the IC ETC indicator circuit, the IC sends a message notifying the PCM of the condition, then the IC and the PCM will each store a DTC.

For proper diagnosis of the ETC system, the PCM, the IC, the CAN data bus or the electronic communication related to ETC indicator operation a diagnostic scan tool is required. Refer to the appropriate diagnostic information.