Left rear door when opened, does not activate the interior lights

Principles of Operation
Interior Lighting The interior lighting is broken down into two groups: the courtesy lamps and the illuminated entry lamps. Both lighting features interact with the courtesy light arbitrator. The battery saver is also listed in this section.
Courtesy Lighting The courtesy lamps consist of the dome lamp and/or map lights. The courtesy lamps can be activated by the GEM using the panel dimmer switch, or by any ajar door. The courtesy lamps will shut off when the doors are closed and the illuminated entry feature is not active, or when the vehicle speed is greater than 8 kph (5 mph). The interior lamps will not be reactivated until the vehicle speed is less than 5 kph (3 mph) and a new door open warning lamp switch signal is received. The inputs are:

• ignition switch position

• driver door ajar switch

• front passenger door ajar switch

• rear left door ajar switch

• rear right door ajar switch

• vehicle speed switch (VSS)

The outputs are:

• battery saver relay

• interior lamp relay

Interior lights and the power door locks are controlled by a electronic control module . Hooking up a factory or some other type professional scan tool an checking for codes an viewing input data to these control modules would be the first thing to do.
The interior lighting system consists of the following:

• lighting control module (LCM)
• driver door module (DDM)
• instrument panel
• dome/map combination
• courtesy/reading lamps
• orientation light
• door lamps
• footwell lamps
• luggage compartment lamp
• glove compartment lamp
• vanity mirrors
• door ajar switches
• viewing wiring diagrams an checking power and ground circuits for these modules would be the next step if no codes were found . Principles of Operation
  Lighting Control Module This vehicle uses a lighting control module (LCM). The LCM is a microprocessor-based module that controls several vehicle subsystems, responds to electrical input signals from various switches, sensors, and external modules and is located on the LH side of the instrument panel. LCM subsystem functions include:
  
  • headlamps with autolamps
  • turn signal lamps/hazard flasher lamps
  • cornering lamps
  • parking lamps
  • daytime running lamps
  • interior lamps
  • demand lamps
  • battery saver
  The LCM interfaces with the driver door module (DDM) via the standard corporate protocol (SCP) network for the illuminated entry feature.
  The interior lamp is illuminated by pressing the individual interior lamp switch. The interior lamp is also illuminated by door ajar switches located in the door latches, when any door is opened. A theater lighting feature gradually increases or decreases the light intensity when switched by opening or closing a door.
  The dome/map lamp combination are located on each side of the interior lamp. The map lamps are operated independently of the interior lamp by two switches located on the interior lamps.
  The interior lamps are illuminated by holding the panel dim switch in the UP position until the dome lamps turn on. The interior lamp also illuminates when a door is opened and actuates the door ajar warning lamp switch in the door latch.
  The front map lamps are powered by the demand lighting circuit and the interior lighting circuit.
  The rear passenger reading lamps are incorporated into the rear seat assist handle and are located over the rear door openings. These lamps are illuminated through power supplied by the LCM demand lighting circuit.
  Interior lamps (controlled by the LCM) are activated by using the dome lamp switch (instant ON/OFF response) or when a door is ajar. The following lamps illuminate for interior lighting:
  
  • instrument panel interior lamps
  • front map lamps
  • rear reading lamps
  • door lamps
  Demand lighting includes lamps that are illuminated by the customer by directly actuating a switch. The front dome/map lamps are located in the overhead console. Each lamp is controlled by its own switch.
  The following demand lamps are powered by the demand lighting output of the LCM:
  
  • glove compartment lamp
  • vanity mirror lamp
  • luggage compartment lamp
  Each lamp has a dedicated switch that closes to ground to illuminate the lamp.
  The front map lamps are powered by either the demand lighting circuit or the interior lighting circuit, depending upon the position of the switch associated with each lamp. When the customer turns the front map lamp switch ON, the front map lamp is illuminated through power supplied by the LCM demand lighting circuit. If the customer moves the map lamp switch to the OFF position, the power from the LCM demand lighting circuit is interrupted and the lamp is reconnected to the interior lighting circuit.
  The rear reading lamps are powered by either the interior lighting circuit or the demand lighting circuit.
  The luggage compartment lamp is controlled by the trunk ajar switch, and is powered by the demand lighting output from the LCM, and is mounted near the center of the upper rear panel.
  The glove compartment lamp system consists of a glove compartment lamp switch and wire and miniature bulb assembly. Opening the glove compartment door closes the switch which provides power to the glove compartment lamp switch and wire. The glove compartment lamp switch is grounded to the body sheet metal.
  The vanity mirror lamp system consists of a switch and bulb assembly in the RH inside visor and the LH inside visor. Lifting the vanity mirror cover closes the vanity mirror lamp switch and provides power to the lamps.
  The illuminated entry system is controlled by the LCM and provides interior lighting upon entry to the vehicle.
  Interior lamps will be illuminated for 25 (±1) seconds which includes a theater lighting ramp-up time (0.5 seconds). This time interval does not include the theater lighting ramp-down time. Interior lamps will be turned off before the 25 (±1)-second timeout if the ignition switch is turned to the RUN or ACC position.
  The illuminated entry system has the following additions to accommodate the remote entry system: pressing the unlock button on the remote transmitter will activate the illuminated entry system (with theater ramp-up). When the driver door module detects a button press, it sends a signal on the J1850 communication network activating the interior lamps. The lighting control module will turn off the lamps by sensing the all doors lock signal.
  The battery saver feature prevents excessive drain from loads inadvertently left on. When the ignition switch is turned OFF, power is interrupted to the interior lamps and headlamps (after a 10-minute timeout) and the demand lamps (after a 30-minute timeout).
  The battery saver has the following inputs:
  
  • luggage compartment door ajar switch
  • dome lamp switch
  • ignition switch status
  • illuminated entry signal
  • headlamp switch
  • driver/passenger door ajar entry switch
  • keyless entry remote transmitter
  • door unlock, luggage compartment door release

The BCM receives battery voltage from the CTSY/RF TRN fuse in order to supply power to the courtesy lamps. The BCM applies this voltage to the courtesy lamps through the courtesy lamp supply voltage circuits. When any door is opened, the door open switch contacts close and the BCM receives a door-open signal. If the BCM receives a door lock or unlock signal, the BCM will activate the courtesy lamp supply voltage circuit, providing battery voltage to the dome lamps and the left and right footwell courtesy lamps. The courtesy lamps can be manually activated by placing the interior lamp switch in the DOME position. For more detailed information concerning courtesy lamp operation refer to Interior Lighting Systems Description and Operation.
The BCM receives battery voltage from the INT LAMPS fuse in order to supply power to the inadvertent courtesy lamps. Inadvertent power courtesy lamp feature provides a similar function for the interior lamps as a retained accessory power feature. The BCM will energize the courtesy lamps supply voltage circuit when the BCM is in the active state (awake). When the inadvertent power courtesy lamps supply voltage circuit is energized, it supplies voltage to all the interior lights listed below. The BCM will continue to supply voltage to the interior lamps after the ignition is turned OFF so that the interior lamps may be operated.

courtesy light switch , is door ajar switch an it's part of the door lock actuator . Light on coming on ? Not going off ? The ajar switch is a input to the GEM module , fords BCM - body control module . The GEM will energize a relay to turn on the lights .
The GEM will illuminate the interior lamps when any door is open or ajar. The interior lamps are; the dome lamp, the rear cargo lamp, the door courtesy lamp and the side rail lamps. The courtesy lamps will shut off when the doors are closed and the illuminated entry feature is not active or when the vehicle speed is greater than 5 mph (8 km/h). The interior lamps will not be reactivated until the vehicle speed is less than 3 mph (5 km/h) and a new door open warning lamp switch is received.
The GEM controls the interior lamps illuminated entry function by activating the interior lamp relay.
Mite be a good idea to have it check for DTC'S - diagnostic trouble codes .

B1322 Driver Door Ajar Circuit Short to Ground GEM GO to Pinpoint Test B . B1323 Door Ajar Lamp Circuit Failure GEM REFER to Section 413-01 . B1325 Door Ajar Lamp Circuit Short to Battery GEM REFER to Section 413-01 . B1330 Passenger Door Ajar Circuit Short to Ground GEM REFER to Section 417-02 . B1334 Decklid Ajar Rear Door Circuit Short to Ground GEM GO to Pinpoint Test C . B1338 Door Ajar RR Circuit Short to Ground

Overhead Console Lamp and Roof Rail Courtesy/Reading Lamps
The courtesy/reading lamp is a duel purpose lamp that can be illuminated two different ways. First, the lamp can be turned ON during courtesy lamp operation as described above. Second, the lamps can be turned ON individually for reading lamp operation by the lamp switch. The BCM supplies battery voltage from the INT LAMPS fuse through the inadvertent power courtesy lamps circuit to the courtesy/reading lamps for reading lamp operation only. Ground for the courtesy lamp module or the roof/rail reading lamps is provided at G402

Courtesy Lamps
When either one of the front doors is opened, ground is applied through the door latch door open switch and the door open switch signal circuit to the door module indicting the door open position. In response to this signal, the door module sends a GMLAN serial data message to the BCM of the door open position. Or, when either one of the rear doors is opened, ground is applied through the door latch door open switch and the rear door open switch signal circuit to the BCM is indicating the rear door open position. Once a door open message or signal received, the BCM will then apply battery voltage from the CTSY/RF TRN fuse through the courtesy lamp supply voltage circuits illuminating the lamps listed below:
• Overhead console lamp
• Roof rail courtesy lamps
• Footwell courtesy lamps The BCM receives battery voltage from the INT LAMPS fuse in order to supply power to the inadvertent courtesy lamps. Inadvertent power courtesy lamp feature provides a similar function for the interior lamps as a retained accessory power feature. The BCM will energize the courtesy lamps supply voltage circuit when the BCM is in the active state (awake). When the inadvertent power courtesy lamps supply voltage circuit is energized, it supplies voltage to all the interior lights listed below. The BCM will continue to supply voltage to the interior lamps after the ignition is turned OFF so that the interior lamps may be operated.
• Overhead Console Reading Lamps
• Roof Rail Reading Lamps
• Vanity Mirror Lamps
• I/P Compartment Lamp
• Rear Compartment Courtesy Lamp
In the event that any of these lamps were to remain illuminated for a period of more than 20 minutes with the ignition switch in the OFF position and no BCM input activity, the BCM will deactivate the inadvertent power supply voltage circuit to prevent a total battery discharge condition. The BCM receives battery voltage from the CTSY/RF TRN fuse in order to supply power to the courtesy lamps. The BCM applies this voltage to the courtesy lamps through the courtesy lamp supply voltage circuits. When any door is opened, the door open switch contacts close and the BCM receives a door-open signal. If the BCM receives a door lock or unlock signal, the BCM will activate the courtesy lamp supply voltage circuit, providing battery voltage to the dome lamps and the left and right footwell courtesy lamps. The courtesy lamps can be manually activated by placing the interior lamp switch in the DOME position. For more detailed information concerning courtesy lamp operation refer to Interior Lighting Systems Description and Operation.

Courtesy Lights
The courtesy lights come on under the following conditions:
?€¢
Any door is opened.

?€¢
The interior lamp switch is in the ON position.

?€¢
The keyless entry transmitter unlocks the doors (illuminated entry).

When the key is removed from the ignition switch with all of the doors closed, the courtesy lights light for approximately 25 seconds before fading out.
Battery positive voltage (B+) is applied at all times through the IP fuse block CTSY LP/PWR MIR fuse 6A via CKT 640 (ORN) through the body control module (MALL) to the courtesy lights via CKT 1732 (ORN). The MALL provides a ground through CKT 156 (WHT) for the courtesy lights under the following conditions:
?€¢
The MALL receives an input from a door being opened.

?€¢
The MALL receives an input from the interior lamp being turned ON.

?€¢
The MALL receives an input from the doors being unlocked using the keyless entry transmitter.

The courtesy lamps then light.
When the courtesy lights are activated by opening and closing a door, the courtesy lights will remain on for approximately 25 seconds before fading out after all of the doors are closed. If the ignition switch is turned to START or RUN within the 25 seconds, the lights immediately begin to fade out. If a door is left open, the MALL removes battery positive voltage (B+) to the courtesy lights after 10 minutes. When the courtesy lights are activated by the interior lamp switch, the lights remain on as long as the interior lamp switch is in the ON position. When the courtesy lights are activated by unlocking the doors using the keyless entry transmitter, the lights remain on for approximately 40 seconds. If the doors are locked using the keyless entry transmitter within the 40 seconds, the lights immediately begin to fade out.
Body Control Module (MALL) Diagnostic Mode
For a detailed explanation of the MALL module diagnostic mode, refer to Body Control Module Cell 51.
What interior light ? Dome , courtesy lights etc....They don't work with switch, keyless entry , door opening ?
What

Rear fuse box. INT LP 10 amp . there is also INT LP relay in the same rear fuse box .
Fuse Block - Rear
Under the rear seat, on the left side of the floor pan
The INT LP fuse in the fuse block - rear supplies battery positive voltage to the normally open switch contacts of the INT LP relay. The INT LP fuse also supplies battery positive voltage to the INT LP relay control circuit. The fuse block - rear also supplies battery positive voltage to the relay control circuit for the front courtesy lamp. The door modules communicate on a simple bus interface (SBI). When you open any door, the switch contacts of the door open switch close. When a door open signal circuit is grounded, that door module sends a message to the drivers door module (DDM) in order to indicate that a door is open. The DDM sends a class 2 message to the rear integration module (RIM) in order to indicate which door is open. The RIM activates the INT LP relay in order to provide battery positive voltage to the interior courtesy lamps. When any front door is opened, the RIM will energize the FRT CTSY lamp relay grounding the I/Pcourtsey lamps at G302. Depending on which doors are opened, front or rear, the proper interior courtesy lamps illuminate. The RIM provides a pulse width modulated ground to all interior courtesy lamps for the interior lights theater dimming feature. Some of the courtesy lamps are also used as reading lamps, each reading lamp may be manually turned on or off using it's own respective switch

Courtesy Lamps - central junction box. fuse # F1.21 that goes to interior lamp relay in the instrument cluster and F.24 this fuse powers battery saver relay .
Interior Lighting The interior light system consists of the following:

• front map lamp assembly
• front door courtesy lamp
• generic electronic module (GEM)
• glove box lamp assembly
• central security module
• interior lamp switch
• interior lamp relay
• illuminated vanity mirrors (Navigator only)
• reading lamp assembly
• rear courtesy lamp
• running board lamp
• underhood lamp assembly

The generic electronic module (GEM) illuminates the interior lamps when an unlock signal is received from the remote anti-theft personality central security module. The illuminated entry feature will be canceled when any of the following conditions are met:

• 25 seconds have elapsed since the illuminated entry feature was activated and the interior lamp control is not activated (door ajar or courtesy lamp switch on).
• The GEM receives a request from the central security module (remote transmitter lock button pressed) and the interior lamp control is not activated.
• The ignition is in the RUN or START position and the interior lamp control is not activated.

The GEM will illuminate the interior lamps when any door is open or ajar. The interior lamps are; the dome lamp, the rear cargo lamp, the door courtesy lamp and the side rail lamps. The courtesy lamps will shut off when the doors are closed and the illuminated entry feature is not active or when the vehicle speed is greater than 5 mph (8 km/h). The interior lamps will not be reactivated until the vehicle speed is less than 3 mph (5 km/h) and a new door open warning lamp switch is received.
The GEM controls the interior lamps illuminated entry function by activating the interior lamp relay.

You have an electronic control module and relays involved in the operation of these lights also !

What

Door left open chime is operated by your interior light switch. It is located in a few places on different vehicles. Often in the door jam at the front or low down on the pillar at the rear of the door. You will notice a little black rubber boot and when you push it it goes in and out. That is your interior light switch.

check your door jamb switches to make sure they are shutting off the interior lights. They are part of the door latch.

All models have a lamp switch (13713) located in the driver's door latch that activates the interior lamp when the front door (20124) is opened.
I believe right door has one too, and maybe the hatch latch too