When the body control module (BCM) is in an active state (awake) it energizes the courtesy lamps supply voltage circuit. The courtesy lamps supply voltage circuit supplies voltage to all of the interior lamps, including the illuminated entry lamps (courtesy lamps). The illuminated entry lamps are turned ON when they receive a battery positive voltage from the courtesy lamp supply voltage circuit of the BCM. When the ignition is in the LOCK position the BCM will apply the courtesy lamp supply voltage circuit under the following conditions:
• The door jamb input transitions to an active state (opening a door).
• The use of the remote keyless entry (RKE) to unlock the side doors.
Do you know how to do automotive electrical circuit testing using a DVOM- digital volt ohm meter and a wiring diagram to pin point testing areas of a circuit ?
Circuit/System Description
The body control module (BCM) applies battery voltage to the courtesy lamps through 2 separately controlled courtesy lamp supply voltage circuits. When any door is opened, the door ajar switch contacts close and the BCM receives a door-ajar input. If the BCM receives a door lock or unlock input or a rear hatch open input, the BCM will activate the courtesy lamp supply voltage circuits, providing battery voltage to all of the instrument panel (I/P) courtesy lamps, dome lamps, rearview mirror lamps, and rear compartment lamps. In the event that any of these lamps were to remain illuminated for more than 20 minutes with the ignition switch in the OFF position, the BCM will deactivate the courtesy lamp control circuits to prevent a total battery discharge condition.
You can view free wiring diagrams here
http://www.bbbind.com/free_tsb.html Enter vehicle info. year , make , model and engine ! Under system click on lighting ,then under subsystem click on interior lighting . Click the search button then the blue link. Looking at the first diagram you will see on the top left a fuse box , this B+ for the BCM ,top right is the BCM .You will see three wires coming out the bottom of the BCM , these go to your courtesy lamps , The thing's that look like a open switch inside the BCM , they are transistors or high side drivers . When commanded these supply B+ voltage to the lights . Finding the BCM an testing output voltage would be my first step , before taking the inside of the vehicle apart to find wiring harness to test .
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