Interior Lighting System: Overview Ford Fiesta Mk6

The interior lighting system consists of the following components

1. Interior/map lamps
2. Luggage compartment lamp
3. Door ajar switches (integrated into the door latches)
4. Luggage compartment lid/liftgate ajar switch (integrated into the luggage compartment lid/liftgate latch)
5. Ambient lighting module (located under the center console)
6. Ambient lighting switch (integrated into the passenger heated seat switch)
7. Body Control Module (BCM)

The interior lighting system consists of up to 3 subsystems

1. Courtesy lamps
2. Demand lamps
3. Ambient lighting

Principles of Operation

The Body Control Module (BCM) supplies voltage (and ground for the courtesy lamps) to the interior lighting system. The interior lighting system illuminates the courtesy lamps to enhance visibility of the interior when a vehicle door is ajar. The BCM controls all interior lighting functions and timing by monitoring inputs from the door ajar switches, luggage compartment lid/liftgate ajar switch, door lock switch, input from the Remote Keyless Entry (RKE) system and the ignition state.

The voltage supply circuit to the BCM for the interior lamps is also used for the horn.

Normal Operation

The Body Control Module (BCM) sends a voltage signal to each door ajar switch (integrated into the door latch), which is routed to ground when the door is closed (the door ajar switch is closed when the door is closed). When the door is opened, the signal to ground is interrupted, indicating an open door to the BCM . When the BCM determines a door is open, the battery saver relay energizes (if not already energized) to supply voltage to the interior lamps and the BCM provides ground to the courtesy lamps.

The demand lamp system (map lamps) uses the interior lamps ground circuit.

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. Door latch
3. BCM

The Body Control Module (BCM) supplies voltage and ground to the courtesy lamps when requested. The voltage supply is also used for the demand lamp function (map lamps).

1. DTC B1091:12 (Courtesy Lamp Sense: Circuit Short To Battery) - a continuous and on-demand DTC that sets when the BCMdetects a short to voltage from the courtesy lamp ground controlled circuit.
2. DTC B1D14:11 (Interior Lights Circuit "B": Circuit Short to Ground) - a continuous and on-demand DTC that sets when the BCMdetects a short to ground from the courtesy lamp voltage supply circuit.

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. Interior lamp
3. BCM

The Body Control Module (BCM) sends a voltage signal to the luggage compartment lid/liftgate ajar switch (integrated into the latch) to monitor the ajar switch status. The switch is normally closed when the luggage compartment lid/liftgate is closed, and open when the luggage compartment lid/liftgate is open. The ajar switch also controls the ground side of the luggage compartment lamp. The luggage compartment ajar switch completes the path to ground for the luggage compartment/cargo lamp when the luggage compartment lid/liftgate is open.

1. DTC B1178:92 (Boot/Trunk Ajar Switch: Performance Or Incorrect Operation) - an on-demand DTC that sets when the BCMdetects an open from the luggage compartment lid/liftgate ajar input circuit.

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. Luggage compartment lid/liftgate latch
3. Luggage compartment/cargo lamp

The Body Control Module (BCM) sends a voltage signal to each door ajar switch (integrated into the door latch), which is routed to ground when the door is closed (the door ajar switch is closed when the door is closed). When the door is opened, the signal to ground is interrupted, indicating an open door to the BCM. When the BCM determines a door is open, the battery saver relay energizes (if not already energized) to supply voltage to the interior lamps and then the BCM provides ground to the courtesy lamps.

DTC FAULT TRIGGER CONDITIONS CHART

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. Door latch
3. BCM

The Body Control Module (BCM) sends a voltage signal to the luggage compartment lid/liftgate ajar switch (integrated into the latch) to monitor the ajar switch status. The switch is normally closed when the luggage compartment lid/liftgate is closed, and open when the luggage compartment lid/liftgate is open. The ajar switch also controls the ground side of the luggage compartment lamp. The luggage compartment ajar switch completes the path to ground for the luggage compartment/cargo lamp when the luggage compartment lid/liftgate is open.

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. Luggage compartment lid/liftgate latch

The Body Control Module (BCM) supplies voltage to the interior lamps when the battery saver feature is not active. This voltage supply is shared with the courtesy lamps. The interior lamps have a dedicated ground circuit that is used for the map lamps to function independently of the courtesy lamp operation.

This pinpoint test is intended to diagnose the following

1. Wiring, terminals or connectors
2. Interior/map lamps

The Body Control Module (BCM) provides a battery saver function that automatically shuts off of the courtesy lamps after 10 minutes and the demand lamps (map lamps and luggage compartment/cargo lamp) after 30 minutes have elapsed in order to save battery power.

If the courtesy lamps remain on after the battery saver feature activates (10 minutes), go to PINPOINT TEST D .

Refer to INTERIOR LIGHTING , Battery Saver for specific information regarding the conditions which the battery saver activates.

This pinpoint test is intended to diagnose the following

1. Wiring, terminals, or connectors
2. BCM

When the ignition is in any state other than OFF, the Body Control Module (BCM) supplies voltage to the ambient lighting module and the ambient lighting switch. The ambient lighting module supplies voltage and ground to the ambient lighting LEDs. The ambient lighting switch cycles through the 7 color combinations or turns the ambient lighting feature off.

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.

The ambient lighting switch is a momentary contact switch.

1. DTC B12F1:11 (Ambient Lighting Zone 1 Output: Circuit Short To Ground) - a continuous and on-demand DTC that sets when the BCMdetects a short to ground from the ambient lighting module voltage supply circuit.
2. DTC B12F1:15 (Ambient Lighting Zone 1 Output: Circuit Short To Battery Or Open) - a continuous and on-demand DTC that sets when the BCMdetects an open from the ambient lighting module voltage supply circuit.

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
5. BCM

When the ignition is in any state other than OFF, the Body Control Module (BCM) supplies voltage to the ambient lighting module and the ambient lighting switch. The ambient lighting module supplies voltage and ground to the ambient lighting LEDs. The ambient lighting switch cycles through the 7 color combinations or turns the ambient lighting feature off.

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.

The ambient lighting switch is a momentary contact switch.

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

When the ignition is in any state other than OFF, the Body Control Module (BCM) supplies voltage to the ambient lighting module and the ambient lighting switch.

The ambient lighting also has its own illuminated entry/exit strategy. For additional information regarding this strategy, refer to INTERIOR LIGHTING , Illuminated Entry/Exit.

1. DTC B12F1:15 (Ambient Lighting Zone 1 Output: Circuit Short To Battery Or Open) - a continuous and on-demand DTC that sets when the BCMdetects a short to voltage from the ambient lighting module voltage supply circuit.

This pinpoint test is intended to diagnose the following

1. Wiring, terminals, or connectors
2. BCM