Dakota 2WD V8-4.7L VIN J (2005)
Cargo Lamp: Description and Operation
A cargo lamp indicator is standard equipment on all instrument clusters. The cargo lamp indicator is located below the minor gauge set on the left side of
the cluster.
The cargo lamp indicator consists of a stencil-like cutout of the words "CARGO LAMP" in the opaque layer of the instrument cluster overlay. The dark
outer layer of the overlay prevents the indicator from being clearly visible when it is not illuminated. An amber Light Emitting Diode (LED) behind the
cutout in the opaque layer of the overlay causes the "CARGO LAMP" text to appear in amber through the translucent outer layer of the overlay when the
indicator is illuminated from behind by the LED, which is soldered onto the instrument cluster electronic circuit board. The cargo lamp indicator is
serviced as a unit with the instrument cluster.
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
(SKREEM) module.
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:
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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.
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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 instrument cluster continually monitors the headlamp dimmer switch circuit to determine the proper interior lamps features and panel lamps
illumination levels to provide. The cluster then energizes and de-energizes a low side driver circuit to control the exterior cargo lamp. Each time the
instrument cluster energizes the cargo lamp driver and the ignition switch is in the On or Start positions, the cluster also turns on the cargo lamp
indicator. For further diagnosis of the cargo lamp indicator or the instrument cluster circuitry that controls the LED, refer to testing.
For proper diagnosis of the cargo lamp or the headlamp switch inputs to the instrument cluster that control the cargo lamp indicator, a diagnostic scan
tool is required.
