Note: To fully clear EThrottle Fault codes the ECU needs to be power cycled, just clearing the fault codes (deliberately) doesn't reset the EThrottle.
Question
The electronic throttle system appears to operate fine in 'ON - Setup' mode, but when changed to the 'ON' mode the system shuts down. Why is this?
Answer
There are several reasons why the system will shut down when switched to the ON mode but not in the ON - Setup mode.
The ON - Setup mode uses the minimal amount of feedback signals to get the system operating, this makes it easier to check the system and manually diagnose faults. The throttle plate moving with the accelerator pedal in a fashion similar to that of a mechanical system in the ON - Setup does not necessarily mean that the e-throttle system is correctly setup.
When the system is set to the ON mode, both of the main and sub signals for each of the throttle position sensor and accelerator position sensor are considered. If the ECU detects an unexpected voltage from any of these signals the system will shut down.
The following images give example typical feedback signals: (examples are true for booth accelerator and throttle position sensors).
Figure 1 - Typical feedback signal showing the Sub signal not changing at high positions, this is normal.
Figure 2 - Typical feedback signal showing the Sub signal changing at a rate less than the Main, this is normal.
Fault codes generated by the ECU will help you determine which signal is causing a fault. Examine both pairs of feedback signals and make sure they produce voltages with similar relationships as shown in either of the previous two examples.
A very common cause of the sensors producing unexpected voltages relates to wiring issues. Incorrect wiring can quite easily produce non linear feedback signals - check your wiring.
Read the safety features section of this help for more information on fault codes.