Code 45, Idle Switch Circuit, Circuit Grounded Or MISADJUSTED: Notes

Throttle Position (TP) sensor has an idle switch that sends a signal to ECM. ECM applies 5 volts to idle switch. Idle switch is closed with engine at idle (low voltage signal at ECM) and open with engine off idle (high voltage signal at ECM). When ECM detects a low voltage signal, throttle valve is closed and when ECM detects a high voltage signal, throttle valve is open.

Code 45 will set when low voltage input at ECM is indicated with engine running off idle (greater than 2900 RPM), and MAP sensor reading is greater than 320 mm Hg of vacuum, for at least 5 seconds.

1. By disconnecting TP sensor, ECM should detect a high voltage signal and Tech 1 should indicate OFF. Checks for short to ground in Blue/White wire.
2. Checks for short to B+ in Gray/Red wire, or a misadjusted or faulty TP sensor.