For 1990-2009 cars

### Body Control Module (BCM)

The body control module (BCM) controls the interior illumination of the vehicle.

One of the following 3 BCM types is installed on the vehicle based upon the vehicle equipment:

• | BCM type 2

| This provides the interior illumination control, inadvertent load (battery rundown) protection, chime functions and automatic power door locks.

• | BCM type 3

| This provides BCM type 2 features plus the keyless entry system (RPO AUO).

• | BCM type 4

| This provides BCM type 2 and 3 features plus the content theft deterrent (RPO UA6) with remote activation verification and the remote alarm.

For more information regarding the BCM, refer to Body Control System.

### Interior Illumination Control

The BCM activates the interior courtesy lights when the interior lamps override switch is in the ON position (interior courtesy lights enabled).

Additionally, the BCM activates the interior courtesy lights under the following conditions:

• | When any of the vehicle doors are open.

| This includes the left, the right, the sliding door(s) and the rear liftgate door.

• | When the instrument panel (IP) dimmer switch is in the DOME position.

• | When the exit illumination feature is active.

• | When unlocking the doors using the keyless entry transmitter (BCM types 3 and 4 only).

• | When unlocking a door using the left front, the right front or the liftgate door cylinder lock (BCM type 4 only).

The BCM deactivates the interior courtesy lights when all of the doors are closed and the IP dimmer switch is in the OFF position.

All of the vehicle doors contain a door lock ajar switch. When the driver door is open, the left front door lock ajar switch closes, sending a ground signal to the BCM through CKT 159. When the right front or the rear liftgate door is open, its corresponding door lock ajar switch closes, sending a ground signal to the BCM through CKT 49. When a sliding door is open, its corresponding door jamb switch closes, sending a ground signal to the BCM through CKT 54.

The BCM grounds CKT 690 when detecting a ground signal in the following circuits:

• | CKT 49

• | CKT 54

• | CKT 159

When the driver door is closed, the left front door lock ajar switch opens CKT 159. When the right front door and the rear liftgate door are closed, their corresponding door lock ajar switches open CKT 49. When the sliding doors are closed, their corresponding door jamb switches open CKT 54.

The BCM then opens CKT 690 when the following circuits are open:

• | CKT 49

• | CKT 54

• | CKT 159

The BCM uses the voltage in CKT 240 in order to power the interior lights through CKT 328 and CKT 1393. The BCM controls the power supplied in CKT 328 and CKT 1393 for inadvertent load (battery rundown) protection. The BCM opens CKT 690 when the inadvertent load (battery rundown) protection is active (CKT 328 and CKT 1393 are open).

### Delayed Illumination

The BCM grounds CKT 690 for 22-28 seconds, activating the interior courtesy lights when the following conditions are met:

• | The delay illumination is enabled (interior lighting mode 2 or 4).

• | The ignition switch is in the LOCK or the OFF position.

• | The IP dimmer switch is in the OFF position.

• | The interior lamps override switch is in the ON position (interior courtesy lights enabled).

• | When closing all of the vehicle doors (the BCM detects a transition from a ground signal to an open in CKT 49, CKT 54 or CKT 159).

The delayed illumination feature will cancel when any of the following conditions are met:

• | Turning the ignition switch to the ACC or the RUN position.

• | Locking the doors when using either power door lock switch.

• | Locking the doors using the left front, the rear front or the liftgate door key lock cylinder (BCM type 4 only).

• | Locking the doors using a keyless entry transmitter (BCM types 3 and 4 only).

### Exit Illumination

The BCM grounds CKT 690 for 22-28 seconds, activating the interior courtesy lights when the following conditions are met:

• | The exit illumination is enabled (interior lighting mode 3 or 4).

• | The ignition key is removed from the ignition key cylinder (the BCM detects a transition from ground to an open in CKT 80).

• | The IP dimmer switch is in the OFF position.

• | The interior lamps override switch is in the ON position (interior courtesy lights enabled).

• | All of the vehicle doors are closed at the time the ignition key is removed from the ignition key cylinder (CKT 49, CKT 54 and CKT 159 are open).

The exit illumination will cancel when the following conditions occur:

• | Turning the ignition switch to the ACC or the RUN position.

• | Locking the doors when utilizing using the power door lock switch or the keyless entry transmitter.

• | Re-inserting the key into the ignition cylinder within 5 seconds when the exit illumination starts.

### Interior Lighting Modes Feature Customization

Interior Lighting Mode | Delayed Illumination | Exit Illumination
--- | --- | ---
Mode 1 | Disabled | Disabled
Mode 2 | Enabled | Disabled
Mode 3 | Disabled | Enabled
Mode4 | Enabled | Enabled

### Delayed Illumination

• | Enabled (modes 2 and 4): The interior courtesy lights turn ON for 25 seconds, then fade to OFF after the last door is closed.

• | Disabled (modes 1and3): The interior lights turn OFF after the last door is closed.

### Exit Illumination

• | Enabled (modes 3 and 4): The interior courtesy lights turn ON for 25 seconds upon removing the key from the ignition switch.

• | Disabled (modes 1 and 2): The interior courtesy lights stay off upon removing the key from the ignition switch.

### Changing the Interior Lighting Mode

Perform the following procedure to change the interior lighting mode:

1. Turn OFF the I/P dimmer switch.
2. Turn the ignition switch to the LOCK position.
3. Remove the BCM PRGRM fuse.
4. Turn the ignition switch to the ACC position.

• | The BCM sounds the chime a number of times equivalent to the BCM type installed on the vehicle (1,2,3 or 4 chimes).

• | Now the BCM has entered the feature customization mode.

5. To advance the interior lighting mode, cycle the I/P dimmer switch from OFF to DOME and back to OFF.

The BCM sounds the chime a number of times equivalent to the lighting mode currently set. A transition past mode 4 repeats the sequence starting with mode 1.

To exit and save the current customization mode:

1. Turn the ignition switch to the LOCK position.
2. Reinstall the BCM PRGRM fuse.

### Theater Dimming

The BCM dims the interior courtesy lights slowly from a full brightness to the OFF position in 3 seconds. This feature starts anytime the BCM is turning off the interior courtesy lights.

Theater dimming does not work when turning the IP dimmer switch from the DOME position to the OFF position or when the illumination feature is cancelled by locking the doors with a power door lock switch. Also, theater dimming does not work when the exit illumination feature is disabled.

### Door Key Unlock Illumination (BCM Type 4 Only)

The BCM grounds CKT 690 for 36-44 seconds activating the interior courtesy lights, when the following conditions are met:

• | The ignition switch is in the LOCK or the OFF position.

• | The interior lamps override switch is in the ON position (interior courtesy lights enabled).

• | Unlock the left front, the right front or the liftgate door using a door key cylinder lock (grounding CKT 781).

### Keyless Entry Unlock Illumination (BCM Type 3 and 4 Only)

The BCM grounds CKT 690 for 36-44 seconds, activates the interior courtesy lights when the following conditions are met:

• | The ignition switch is in the LOCK or the OFF position.

• | All of the vehicle doors are closed.

• | The IP dimmer switch is in the OFF position.

• | The interior lamps override switch is in the ON position (interior courtesy lights enabled).

• | The BCM receives a message from the Remote Control Door Lock Receiver (RCDLR) in order to unlock the doors.

### Inadvertent Load (Battery Rundown) Protection

The BCM has a feature called inadvertent load (battery rundown) protection. The BCM de-energizes CKT 328 and CKT 1398 9-11 minutes after the ignition switch has been turned from the ACC or the RUN position to the LOCK or the OFF position.

The BCM restores power to CKT 328 and CKT 1393 when the interior lamps override switch is activated (interior courtesy lights enabled) and under the following conditions:

• | Turning the ignition switch from the LOCK or the OFF position, to the ACC or the RUN position.

• | Removing the key from the ignition lock cylinder.

• | Opening any vehicle door.

• | Turning the IP dimmer switch to the DOME position.

• | Activating any of the roof rail reading lights.

• | The BCM receives a message from the Remote Control Door Lock Receiver (BCM type 3 or 4 only).

• | Locking a door using the key (BCM type 4 only).

The inadvertent battery power rundown protection feature is mileage-sensitive. Vehicles with less than 15 (24 km) total accumulated miles (km) have a 2 minute and 32 second - 3 minute and 18 second time-out instead of a 10 minute time-out.

### Vehicle Speed Input

The BCM monitors the vehicle speed input to determine the total distance traveled in order to change the inadvertent battery rundown protection timer.

The BCM determines the distance traveled by interfacing with the vehicle speed CKT 389 which makes a ground transition 4000 times per 1.6 km (1 mile) traveled. Once the vehicle has been driven past the 15 mile (24 km) mark, the BCM changes inadvertent battery power rundown protection timer from 3 minutes to 10 minutes.

In addition, the BCM uses the vehicle speed CKT 389 for the operation of the turn signal reminder.

If the inadvertent battery power rundown protection stays at 3 minutes on vehicles with more than 15 miles (24 km), refer to Audible Warnings for possible malfunction of the turn signal reminder.

### Roof Rail Reading Lamps

These lamps have switches that allow the operator to activate them. The switches, upon activation, provide ground to these lamps turning them to the ON position. The switches obtain ground through CKT 650. The BCM does not turn on these lamps with the rest of the interior courtesy lights. Power to the roof rail reading lamps is provided by the BCM through CKT 328, so that they are protected by the inadvertent load (battery rundown) protection in case they are left in the ON position.

### Windshield Header Courtesy/Reading Lamps

The operation of these lamps is described as part of the interior courtesy lights operation. The BCM provides power (CKT 328) and ground (CKT 690) to these lamps, controlling their operation.

In addition, these lamps have switches that allow the operator to turn them on when the interior courtesy lights are off. The switches, upon activation, provide ground to these lamps turning them to the ON position. The switches obtain ground through CKT 650. Power to these lamps is provided by the BCM through CKT 328, so that they are protected by the inadvertent load (battery rundown) protection in case they are left in the ON position.

### Dome Lamp, IP Courtesy Lamps and Cargo Lamp

The operation of these lamps is described as part of the interior courtesy lights operation. The BCM provides power (CKT 1393) and ground (CKT 690) to these lamps controlling their operation.

### IP Dimmer Switch

The IP dimmer switch allows the operator to activate the interior courtesy lights from inside the vehicle. When the IP dimmer switch is in the DOME position, the switch sends a ground signal to the BCM through CKT 156. This action causes the BCM to activate the interior courtesy lights. When the IP dimmer switch is in the OFF position, the BCM deactivates the interior courtesy lights. With the ignition switch in the LOCK or OFF position, the IP dimmer switch is protected by the inadvertent load (battery rundown) protection in case the IP dimmer switch is left in the DOME position.

The IP dimmer switch is also used to change the interior lighting modes during the feature customization. Refer to Feature Customization for more information. In addition, the IP dimmer switch is also utilized to enter the input/output test during BCM diagnostics.

### Sunshade Illuminated Vanity Mirrors

The sunshade illuminated vanity mirror lamps activate when the mirror cover is open. The sunshade illuminated vanity mirror has a switch that closes (providing ground to the lamps) when the mirror cover is open, and the switch opens when the cover is closed. The switch receives ground through CKT 650.

Power to the sunshade illuminated vanity mirror is provided by the BCM through CKT 328, so that they are protected by the inadvertent load (battery rundown) protection in case that a mirror cover is left open.

### IP Compartment Lamp

The IP compartment lamp activates when the IP compartment is open. The IP compartment lamp has a switch that closes (providing ground to the lamp) when the IP compartment is open. The IP compartment lamp switch opens when the IP compartment is closed. The IP compartment lamp switch receives voltage through CKT 328 and ground through CKT 150. The IP compartment lamp is protected by the inadvertent load (battery rundown) protection in case that the IP compartment is left open.

### Interior Lamps Override Switch

The interior lamps override switch is located in the overhead console switchbank. Pressing the symbol on the bottom of the rocker switch overrides the control of the interior lights. This action interrupts the voltage supply from CKT 1393 to CKT 328, deactivating all of the interior lights.