Transmission Range Switch

WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The Transmission Range (TR) switch is part of the Park/Neutral Position (PNP) and backup light switch assembly, which is externally mounted on the transmission manual shaft. The TR switch contains 4 internal switches that indicate the transmission gear range selector lever position. The ECM 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 ECM detects the selected gear range by deciphering the combination of the voltage signals. ECM compares actual voltage combination of the switch signals to a TR switch combination chart stored in memory.