Liftgate Ajar Indicator: Operation

The liftgate ajar indicator gives an indication to the vehicle operator that the passenger compartment liftgate may be open or not completely latched. This indicator is controlled by a transistor on the instrument cluster circuit board based upon cluster programming and electronic messages received by the cluster from the Central Timer Module (CTM) over the Programmable Communications Interface (PCI) data bus. The liftgate ajar indicator Light Emitting Diode (LED) is completely controlled by the instrument cluster logic circuit, and that logic will allow this indicator to operate whenever the instrument cluster receives a battery current input on the fused ignition switch output (run-start) circuit. Therefore, the LED will always be off when the ignition switch is in any position except On or Start. The LED only illuminates when it is provided a path to ground by the instrument cluster transistor. The instrument cluster will turn on the liftgate ajar indicator for the following reasons:

• Bulb Test  - Each time the ignition switch is turned to the On position the liftgate ajar indicator is illuminated for about two seconds as a bulb test.
• Liftgate Ajar Lamp-On Message  - Each time the cluster receives a liftgate ajar lamp-on message from the CTM indicating that the liftgate is open or not completely latched, the liftgate ajar indicator will be illuminated. The indicator remains illuminated until the cluster receives an liftgate ajar lamp-off message from the CTM, or until the ignition switch is turned to the Off position, whichever occurs first.
• Actuator Test  - Each time the cluster is put through the actuator test, the liftgate ajar indicator will be turned on, then off again during the bulb check portion of the test to confirm the functionality of the LED and the cluster control circuitry.

The CTM continually monitors the liftgate ajar switch to determine the status of the liftgate. The CTM then sends the proper liftgate ajar lamp-on and lamp-off messages to the instrument cluster. For further diagnosis of the liftgate ajar indicator or the instrument cluster circuitry that controls the indicator, (Refer to INSTRUMENT CLUSTER - DIAGNOSIS AND TESTING  ). For proper diagnosis of the liftgate ajar switch and circuits, (Refer to LIGHTING - INTERIOR/LIFTGATE AJAR SWITCH - DIAGNOSIS AND TESTING ). For proper diagnosis of the CTM, the PCI data bus, or the electronic message inputs to the instrument cluster that control the liftgate ajar indicator, a DRBIII(R) scan tool is required. Refer to the appropriate diagnostic information.