Lighting Systems - Interior: Other Jeep Liberty I

COURTESY LAMP CIRCUIT

Depending upon the selected vehicle options the courtesy lamp circuit may include the courtesy lamps located below the instrument panel, the dome or map/reading lamps located in the headliner near the windshield, the cargo lamp located in the headliner near the rear roof header, and the vanity lamps located in the sun visors. The lamps in the courtesy lamp circuit are provided with battery voltage at all times from a fuse in the Junction Block (JB). The Body Control Module (BCM) controls the ground path for these lamps using an internal driver through the courtesy lamp driver circuit based upon hard wired inputs from the door ajar switches, the flip-up glass ajar switch, and the tailgate ajar switch. After all of the ajar switch inputs to the BCM transition to open, the BCM will keep the lamps illuminated for about 27 seconds, then fade the lamps to off (theater dimming) over about three seconds.

The BCM also provides courtesy lamp operation based upon a resistor multiplexed input from the interior lighting control ring on the left control stalk of the multi-function switch through the headlamp switch circuit, and in response to certain inputs from the optional Remote Keyless Entry (RKE) system. A resistor multiplexed courtesy lamp defeat input from the control ring on the left control stalk of the multi-function switch will cause the BCM to override normal courtesy lamp operation based upon inputs from all of the ajar switches. A hard wired input from the courtesy lamp defeat switch in the optional cargo lamp through a rear courtesy lamp control circuit will cause the BCM to override normal courtesy lamp operation based upon inputs from only the flip-up glass and tailgate ajar switches.

For those lamps on the courtesy lamp circuit with independent switching, such as the optional reading lamps and vanity lamps, the BCM provides a ground path to the switches using another internal driver through the courtesy lamp load shed circuit. The BCM provides a battery saver (load shedding) feature for all courtesy lamps, which will automatically turn these lamps off if they are left on for more than about eight minutes with the ignition switch in the Off position.

PANEL LAMPS DIMMER CIRCUIT

The panel lamps dimmer circuit includes the ElectroMechanical Instrument Cluster (EMIC), heater-air conditioner control, hazard switch and, depending upon the selected vehicle options, ash receiver, and automatic transmission range indicator illumination lamps. All lamps in the panel lamps dimmer circuit are provided a path to ground at all times through a hard wired ground circuit. These lamps illuminate based upon inputs to the Body Control Module (BCM) from the exterior lighting control knob and the interior lighting control ring on the left control stalk of the multi-function switch. The control knob on the left control stalk of the multi-function switch selects the exterior lights, while the control ring selects the panel lamps intensity (dimming) level.

When the exterior lighting is turned On, the BCM energizes the park lamp relay and provides an electronic dimming level message to the ElectroMechanical Instrument Cluster (EMIC), the radio, and the Compass Mini-Trip Computer (CMTC) over the Programmable Communications Interface (PCI) data bus. The energized park lamp relay provides a hard wired battery voltage signal input to the EMIC on the park lamp relay output circuit. The EMIC responds to these inputs by supplying a 12-volt Pulse Width Modulated (PWM) output to all of the incandescent lamps in the panel lamps dimmer circuit over the fused panel lamps dimmer switch signal circuit. This shared PWM output synchronizes the selected illumination intensity level of all of the incandescent lamps in the panel lamps dimmer circuit.

The EMIC and the radio each use the electronic dimming level message from the BCM to control and synchronize the illumination intensity of their own Vacuum Fluorescent Display (VFD), while the CMTC uses the dimming level message to control the illumination intensity of both its VFD and its incandescent lighting. In addition, when the control ring on the left control stalk of the multi-function switch is moved to the Parade Mode detent position, all of the VFDs are illuminated at their full intensity levels for increased visibility when the vehicle is driven during daylight hours with the exterior lights turned On.

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