Cargo Lamp Indicator

WARNING: This page is about a different car, the 2013 RAM 3500 HD and 2013 RAM 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.

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 hardwired multiplex input received by the cluster from the cargo lamp switch on the headlamp dimmer switch mux circuit.

The cargo lamp indicator Light Emitting Diode (LED) is completely controlled by the instrument cluster logic circuit and is only on when the cargo lamp is on. The cargo lamp indicator also remains active when the key is out of the ignition. 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 exterior lamps load shed (about fifteen minutes).

The Instrument Panel Cluster (IPC) continually monitors the headlamp dimmer switch circuit to determine the proper interior lamps features and panel lamps illumination levels to provide. The IPC then energizes and de-energizes a low side driver circuit to control the exterior cargo lamp. Each time the IPC energizes the cargo lamp driver and the ignition switch is in the ON or START positions, the IPC also turns ON the cargo lamp indicator. For further diagnosis of the cargo lamp indicator or the IPC circuitry that controls the indicator. Refer to DIAGNOSIS AND TESTING .