Operation

OPERATION

The cargo lamp indicator gives an indication to the vehicle operator when the exterior cargo lamp is illuminated. This indicator is controlled by a transistor on the instrument cluster circuit board based upon cluster programming, a hard wired multiplex input received by the cluster from the cargo lamp switch on the headlamp dimmer switch mux circuit, and electronic unlock request messages received from the optional Sentry Key REmote Entry Module (SKREEM) (also known as the Wireless Control Module/WCM).

The cargo lamp indicator Light Emitting Diode (LED) is completely controlled by the instrument cluster logic circuit, and that logic will only allow this indicator to operate when 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 cargo lamp indicator for the following reasons:

- Cargo Lamp-On Input - Each time the cluster detects a cargo lamp-ON input from the headlamp switch on the headlamp dimmer switch mux circuit, the cargo lamp and the cargo lamp indicator will be illuminated. The cargo lamp and indicator remain illuminated until the cluster receives a cargo lamp-OFF input from the headlamp switch, until the cluster has completed an interior lamps load shed (about five minutes), 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 cargo lamp 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 ElectroMechanical Instrument Cluster (EMIC) continually monitors the headlamp dimmer switch circuit to determine the proper interior lamps features and panel lamps illumination levels to provide. The EMIC then energizes and de-energizes a low side driver circuit to control the exterior cargo lamp. Each time the EMIC energizes the cargo lamp driver and the ignition switch is in the ON or START positions, the EMIC also turns ON the cargo lamp indicator.

The hard wired headlamp switch input and circuit related to cargo lamp indicator operation may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information.