Circuit Description

WARNING: This page is about a different car, the 2002 GMC Sierra, 2002 GMC Cab & Chassis Sierra, 2002 Chevrolet Silverado, and 2002 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The indicator lamps circuit consist of four individual indicators contained inside the transfer case shift control switch. They are 2HI, 4HI, 4LO and Neutral. The 2HI, 4HI, and 4LO indicators are contained inside their respective range button. When the ignition in ON, the transfer case shift control module illuminates the indicator that corresponds to the current ATC gear position by providing a ground through a current limiting driver.

The transfer case shift control module flashes each indicator after a shift has been requested and will continue to flash until the transfer case shift control module can complete the shift.

A solid state circuit located inside the switch supplies ignition voltage to the indicators. The solid state circuit also receives voltage whenever the headlamp switch is in the parklamp or headlamp position. When the solid state circuit receives voltage from the headlamp switch, the circuit will reduce the voltage supplied to the indicators, dimming the indicators when the headlamps are ON.