Circuit/System Description

The S45B Liftgate Release Switch has a push button switch to command the liftgate to open and close. The K9 Body Control Module monitors the voltage level on the open/close signal circuit 4652, when the switch is not being pressed the voltage level is at 7.5 volts. When the switch is pressed a contact within the S45B Liftgate Release Switch closes providing a ground path for the signal circuit causing the voltage level to drop to near zero volts. The K9 Body Control Module will detect the voltage drop and will send a serial data message to the K194 Rear Gate Module to command the liftgate to open or close depending upon the current state of the liftgate at the time the switch is pressed.

The S45B Liftgate Release Switch contains 3 resistors which are in series for the liftgate mode, depending upon which position is selected will determine which combination of resistors are used. The K194 Rear Gate Module monitors the voltage level in the Rear Closure Actuation On/Off Switch Signal circuit 4653, as each mode is selected, the voltage within the signal circuit incrementally drops. It is this method the K194 Rear Gate Module will determine if mode switch is in the manual mode, garage mode or the maximum open mode.

The unlatch, primary, and neutral switches are part of the liftgate latch and are used by the rear gate module to determine the state of the latch during the process of cinching or unlatching. The unlatch and primary switches will be inactive when the primary and secondary latches are latched, and the neutral switch will be active during the power cinch function. Each of the latch switch signal circuits are supplied signal through a resistor and monitored within the rear gate module. The latch switches share a common low reference circuit from the rear gate module and when the switch contacts close, the signal circuit goes low and the rear gate module determines the switch to be active.

The rear gate module continuously monitors power liftgate operation and calculates its location and direction of travel using 2 Hall effect sensors that are part of the liftgate motor. The Hall effect sensors are 12 V 3-wire sensors and are supplied with a 12 V reference, ground and signal circuits from the rear gate module. The Hall effect sensor signal circuits are referenced from voltage within the rear gate module and pulsed low by the Hall effect sensors.