Circuit Description

WARNING: This page is about a different car, the 2010 GMC Sierra and 2010 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The internal mode switch (IMS)/transmission range (TR) switch is part of the park/neutral position (PNP) and backup lamp switch assembly, which is internally mounted on the transmission manual shaft. The IMS/TR switch contains four internal switches that indicate the transmission gear range selector lever position. The transmission control module (TCM) or powertrain control module (PCM) supplies ignition voltage to each switch circuit. As the gear range selector lever is moved, the state of each switch may change, causing the circuit to open or close. An open circuit or switch indicates a high voltage signal. A closed circuit or switch indicates a low voltage signal. The TCM/PCM detects the selected gear range by deciphering the combination of the voltage signals. The TCM/PCM compares the actual voltage combination of the switch signals to an IMS/TR switch combination chart stored in memory.

The PNP switch contains one internal switch that indicates the transmission gear range selector lever position when in Park and Neutral. The engine control module (ECM)/PCM supplies ignition voltage to the PNP switch circuit. As the gear range selector lever is moved, the state of the PNP switch changes, causing the circuit to open or close. An open circuit or switch indicates a high voltage signal. A closed circuit or switch indicates a low voltage signal. The ECM/PCM detects the Park and Neutral ranges by voltage signal.