Circuit Description

WARNING: This page is about a different car, the 2002 Buick Regal, 2002 Buick Century, 2001 Buick Regal, and 2001 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.

The Transaxle Range (TR) switch is part of the Park/Neutral Position (PNP) and back-up lamp switch assembly, which is externally mounted on the transaxle manual shaft. The TR switch contains four internal switches that indicate the 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 table stored in memory. See TRANSAXLE RANGE SWITCH LOGIC table.

TRANSAXLE RANGE SWITCH LOGIC

Gear Selector Position	Signal "A"	Signal "B"	Signal "C"	Signal "P"
"P"	LOW	HI	HI	LOW
"R"	LOW	LOW	HI	HI
"N"	HI	LOW	HI	LOW
"D4"	HI	LOW	LOW	HI
"D3"	LOW	LOW	LOW	LOW
"D2"	LOW	HI	LOW	HI
"D1"	HI	HI	LOW	LOW