Circuit/System Description

WARNING: This page is about a different car, the 2016 Cadillac ATS. However, it is still accessible from the selected car via links, so may be relevant.

The park/neutral position switch is internal to and part of the internal mode switch. The park/neutral switch indicates to the engine control module (ECM) if the vehicle is in park/neutral or in a drive gear range. With the ignition On, the ECM provides 12 V on the park/neutral signal to the park/neutral position switch. A separate ground wire from the park/neutral position switch to the Transmission Control Module (TCM) completes the path to ground. When the gear shift lever in park or neutral, the switch closes and drops the voltage on the signal circuit to 0 V. In this state the engine will start and run. In reverse or drive range the park/neutral switch opens, 12 V is then present on the signal circuit which will inhibit engine starting.