Interior Lighting System: Overview Ford Flex I

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. Ambient lighting module (if equipped) (mounted under the bottom of the floor center console)
2. Ambient lighting switch (if equipped)
3. Door ajar switches (part of the door latch)
4. Instrument panel dimmer switch
5. Interior/map lamps
6. Liftgate ajar switch
7. Liftgate/Trunk Module (LTM) (if equipped)
8. Puddle lamps
9. SJB
10. Vanity mirror lamps

The interior lighting system consists of 3 subsystems

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

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 to enhance visibility of the interior while a vehicle door is ajar, and the vehicle speed is less than 15 km/h (9 mph) or 5 km/h (3 mph) for puddle lamps. The SJB controls all interior lighting functions and timing by monitoring inputs from the door ajar switches, the instrument panel dimmer switch and vehicle speed.

Normal Operation

When any door is opened, the door ajar switch opens the circuit to the Smart Junction Box (SJB). The SJB monitors the door ajar circuits, and based on the status, the SJB supplies voltage to the courtesy lamps.

The SJB also sends a voltage reference signal to the instrument panel dimmer switch to monitor the dome defeat input request. When the instrument panel dimmer switch is in the DOME DEFEAT position, the signal is routed to ground, indicating a request for the dome defeat feature.

When any door is opened, a correct unlock code from the keyless entry keypad or an unlock request from a programmed Remote Keyless Entry (RKE) transmitter is detected, the SJB provides voltage to the courtesy lamps unless the dome defeat from the instrument panel dimmer switch is detected.

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. Door ajar switch (part of the door latch)
3. Instrument panel dimmer switch
4. SJB

When the liftgate is opened, the liftgate ajar switch (or Liftgate/Trunk Module (LTM), if equipped) opens the ground signal to the Smart Junction Box (SJB). The SJB monitors the liftgate ajar circuit, and based on the ajar status, supplies voltage to the courtesy lamps.

1. DTC B2721 (Liftgate/Decklid Ajar Output Short To Ground Or Open) - a continuous and on-demand DTC that sets when the LTM detects a short to ground from the liftgate ajar input circuit to the SJB .

This pinpoint test is intended to diagnose the following

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

The Smart Junction Box (SJB) monitors the instrument panel dimmer switch status to determine if the courtesy lamps are requested. When the instrument panel dimmer switch is rotated to the DOME LAMP position, the instrument panel dimmer switch provides ground on the dome lamp input circuit to the SJB . Based on the dimmer switch status, the SJB supplies voltage to the courtesy lamps.

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. Instrument panel dimmer switch
3. SJB

Power is supplied to the courtesy lamps through the Smart Junction Box (SJB) fuse 9 (15A). When any door or the liftgate is opened, the ajar switch opens, signaling the SJB . The SJB monitors the ajar switches, instrument panel dimmer switch and Integrated Keyhead Transmitter (IKT) input. Based on the input status, the SJB supplies voltage to the courtesy lamps.

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

This pinpoint test is intended to diagnose the following

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

The Smart Junction Box (SJB) provides voltage to the puddle lamps. The puddle lamps have separate ground circuits.

1. DTC B2A39 (Puddle Lamp Output Circuit Open) - an on-demand DTC that sets when the SJB detects an open on the puddle lamp output circuit.
2. DTC B2A3A (Puddle Lamp Output Circuit Short To Ground) - a continuous and on-demand DTC that sets when the SJB detects a short to ground on the puddle lamp output circuit. This DTC also sets when the SJB fuse 10 (15A) has failed or is removed.

This pinpoint test is intended to diagnose the following

1. Fuse
2. Wiring, terminals or connectors
3. Exterior mirror
4. Puddle lamp
5. SJB

When any door or the liftgate is opened, the door ajar switch, the liftgate ajar switch (or the Liftgate/Trunk Module (LTM), if equipped) opens the circuit to the Smart Junction Box (SJB) to indicate a request for the courtesy lamps. When the instrument panel dimmer switch is rotated to the DOME LAMP position, ground is supplied on a single circuit to the SJB . The SJB monitors the ajar circuits and the dome input circuit. Based on the inputs, the SJB supplies voltage to the courtesy lamps.

DTC DESCRIPTION AND FAULT TRIGGER CONDITIONS

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. Door ajar switch (part of the door latch)
3. Liftgate ajar switch (part of the liftgate latch)
4. Instrument panel dimmer switch
5. LTM
6. SJB

Based on the input status, the Smart Junction Box (SJB) supplies voltage to the courtesy lamps.

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. Interior lamp

The Smart Junction Box (SJB) provides voltage to the puddle lamps.

1. DTC B2A39 (Puddle Lamp Output Circuit Open) - an on-demand DTC that sets when the SJB detects a short to voltage on the puddle lamp output circuit.

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. SJB

The Smart Junction Box (SJB) energizes the battery saver relay based on inputs from the ignition key position, ajar switches, Integrated Keyhead Transmitter (IKT), keypad and the instrument panel dimmer switch (when rotated to the dome position). When the battery saver relay is energized, it supplies voltage to the demand lamps.

This pinpoint test is intended to diagnose the following

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

The Smart Junction Box (SJB) supplies voltage to the demand lamps.

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. Interior lamp

The Smart Junction Box (SJB) provides a battery saver function. The battery saver function provides automatic shutoff of the interior lamps (courtesy lamps and demand lamps) after 10 minutes has elapsed in order to save battery power.

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
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, the 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 receive voltage. When the ambient lighting switch is pressed, voltage is routed to the ambient lighting module, 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, the 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. When the ambient lighting switch is pressed, voltage is routed to the ambient lighting module, 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