K 1500 Suburban 4WD V8-5.3L VIN Z Flex Fuel (2003)
Neutral Safety Switch: Description and Operation
4L60-E/4L65-E
Transmission Range Switch
The transmission range (TR) switch is part of the park/neutral position (PNP) and backup lamp switch assembly, which is externally mounted on the
transmission manual shaft. The TR switch contains four internal switches that indicate the transmission gear range selector lever position. The 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 PCM detects the
selected gear range by deciphering the combination of the voltage signals. The PCM compares the actual voltage combination of the switch signals to a
TR switch combination chart stored in memory.
