Interior Lighting System: Overview Mercury Mariner II

Note. The smart junction box (SJB) is also known as the generic electronic module (GEM).

The interior lighting system consists of the following components

1. SJB
2. Dimmer control switch
3. Interior/map lamps
4. Cargo lamp
5. Vanity mirror lamps
6. Door ajar switches (integral to door latch)
7. Liftgate/liftgate glass ajar switches
8. Ambient lighting module (if equipped)
9. Ambient lighting switch (if equipped)

The interior lighting system may consist of up to 3 subsystems

1. Courtesy lamps
2. Demand lamps
3. Ambient lighting (if equipped)

Principles of Operation

Note. The smart junction box (SJB) is also known as the generic electronic module (GEM).

The SJB supplies voltage to the interior lighting system. The interior lighting system illuminates the courtesy lamps while a vehicle door is ajar, and the vehicle speed is less than 5 km/h (3 mph). The SJB controls all interior lighting functions and timing by monitoring inputs from the door ajar switches, the dimmer switch, and the vehicle speed.

Normal Operation

Power is supplied to the courtesy lamps through the smart junction box (SJB) fuse 9 (15A), which supplies voltage to the courtesy lamps solid-state relay in the SJB. When any door is opened, the ajar switch opens, signaling the SJB. The SJB monitors the ajar circuits, and based on the ajar status, the SJB energizes the solid-state relay supplying voltage to the courtesy lamps on circuit VLN33 (GY/VT). The SJB also monitors the dome defeat output through circuit CLN27 (WH/BN). A short to ground on circuit CLN27 (WH/BN) will cause the courtesy lamps to be inoperative. Ground for the courtesy lamps is supplied through circuit GD182 (BK/GY).

1. DTC B2A35 (Courtesy Lighting Output Circuit Open) - is an on-demand DTC that sets when the SJB detects an open from the courtesy lighting circuit.
2. DTC B2A36 (Courtesy Lighting Output Circuit Short to Ground) - is a continuous and on-demand DTC that sets when the SJB detects a short to ground from the courtesy lighting circuit.

This pinpoint test is intended to diagnose the following

1. Fuse
2. Wiring, terminals or connectors
3. Dimmer switch
4. SJB

Circuit VLN33 (GY/VT) provides voltage to each demand lamp when activated. The demand lamps are grounded through circuit GD182 (BK/GY). The battery saver function of the smart junction box (SJB) deactivates the voltage to the demand lamps after time-out.

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. Lamp assembly

When any door, liftgate, or liftgate glass is opened, the ajar switch opens the circuit to the smart junction box (SJB). The smart junction box (SJB) monitors the dimmer switch status on circuit CLN17 (BN) to determine if the courtesy lamps are requested. The SJB monitors the door ajar and dimmer switch input circuits, and based on the status, the SJB supplies voltage to the courtesy lamps on circuit VLN33 (GY/VT).

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. Dimmer switch
3. Door ajar switch (part of door latch)
4. Liftgate ajar switch (part of liftgate latch)
5. Liftgate glass ajar switch (part of liftgate window latch)
6. SJB

When any door is opened, the ajar switch opens the circuit to the smart junction box (SJB). The SJB monitors the ajar circuits, and based on the ajar status, the SJB supplies voltage to the courtesy lamps on circuit VLN33 (GY/VT).

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. Door ajar switch (part of door latch)
3. SJB

When the liftgate or the liftgate glass is opened, the ajar switch opens the circuit to the smart junction box (SJB). The SJB monitors the ajar circuits, and based on the ajar status, the SJB supplies voltage to the courtesy lamps on circuit VLN33 (GY/VT).

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. Liftgate ajar switch (part of the liftgate latch)
3. Liftgate glass ajar switch (part of the liftgate glass latch)
4. SJB

The smart junction box (SJB) monitors the dimmer switch status on circuit CLN17 (BN) to determine if the courtesy lamps are requested. Based on the dimmer switch status, the SJB supplies voltage to the courtesy lamps through circuit VLN33 (GY/VT).

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. Dimmer switch
3. SJB

The smart junction box (SJB) supplies voltage to the demand lamps on circuit CLN09 (YE/GN). The demand lamps are grounded through circuit GD182 (BK/GY).

This pinpoint test is intended to diagnose the following

1. Fuse
2. Wiring, terminals or connectors
3. SJB

Circuit CLN09 (YE/GN) provides voltage to each demand lamp when the battery saver relay is activated. The demand lamps are grounded through circuit GD182 (BK/GY). The battery saver function of the smart junction box (SJB) deactivates the voltage to the demand lamps after time-out.

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. Lamp assembly

The smart junction box (SJB) provides a battery saver function. The battery saver function provides automatic shutoff of the interior lamps (demand lamps and glove compartment lamp) after a predetermined time has elapsed in order to save battery power.

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. SJB

The illuminated entry provides courtesy lighting whenever the smart junction box (SJB) receives a lamps on/doors unlock request from the remote keyless entry (RKE) transmitter. The SJB provides the voltage and ground circuits for the courtesy/map lamps.

This pinpoint test is intended to diagnose the following

1. RKE transmitter
2. SJB

When the ignition key is in the RUN or ACCESSORY position, the ambient lighting module supplies voltage and ground to the LEDs located in the floor console cup holders, storage tray, storage bin and the front and rear footwells. The ambient lighting switch is used to cycle through the 7 color combinations or to turn the ambient lighting feature off. There are 3 different color (red, blue and green) LEDs housed within each LED assembly.

When the ignition key is in the RUN or ACCESSORY position, the ambient lighting switch and the ambient lighting module receives voltage through circuit CBX07 (GN/RD). Ground for the ambient lighting module is provided through circuit GD908 (BK). When the ambient lighting switch is pressed, voltage is routed to the ambient lighting module through circuit CLN54 (BN/YE), indicating a request for the module to cycle the ambient lighting to the next setting.

This pinpoint test is intended to diagnose the following

1. Fuse
2. Wiring, terminals or connectors
3. Ambient lighting harness
4. Ambient lighting switch
5. Ambient lighting module

When the ignition key is in the RUN or ACCESSORY position, the ambient lighting module supplies voltage and ground to the LEDs located in the floor console cup holders, storage tray, storage bin and the front and rear footwells. The ambient lighting switch is used to cycle through the 7 color combinations or to turn the ambient lighting feature off. There are 3 different color (red, blue and green) LEDs housed within each LED assembly.

When the ignition key is in the RUN or ACCESSORY position, the ambient lighting switch and the ambient lighting module receives voltage through the circuit CBX07 (GN/RD). Ground for the ambient lighting module is provided through circuit GD908 (BK). When the ambient lighting switch is pressed, voltage is routed to the ambient lighting module through circuit CLN54 (BN/YE), indicating a request for the module to cycle the ambient lighting to the next setting.

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. Ambient lighting switch
3. Ambient lighting harness
4. Ambient lighting module