Code 45, Idle Switch Circuit Circuit Grounded Or MISADJUSTED

This code sets if ECM sees an open switch or circuit at idle conditions. When properly adjusted, the TPS idle switch pulls ECM circuit low (to ground) when throttle is closed. If idle switch is measured separately, it shows little or no resistance when closed. When throttle is opened, the circuit goes high at the ECM. If idle switch is measured separately, it shows open or infinite resistance.

1. With throttle wide open, TPS idle switch should be open.
2. This checks for TPS harness shorted to ground at throttle body.
3. This checks for short to ground or circuits shorted together on ECM side of TPS connector.

Fig 1: Code 45 Circuit Diagram & Flow Chart