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Interior Lighting System: Overview Ford Transit VII

Interior/illumination Lights ~697 words

The interior lighting system consists of the following

  1. Courtesy lamp relay
  2. Door ajar switches
  3. Interior lamp(s)
  4. Central Junction Box (CJB)
  5. Generic Electronic Module (GEM)

The interior lighting system consists of 2 subsystems

  1. Courtesy lamps
  2. Demand lamps

Principles of Operation

When the ignition is in ACC on RUN, or before the battery saver feature times out, the Generic Electronic Module (GEM) supplies voltage to the front interior lamp. The GEM controls the courtesy lamp relay, and when energized supplies ground, activating the courtesy lamps (the front interior lamp control switch must be in DOOR position). The front interior lamp has a dedicated ground circuit for the demand lamps. When the front interior lamp control switch is in the ON position, the switch closes to ground activating the demand lamps.

Both of the rear interior lamps receive voltage from the GEM , and are supplied a controlled ground from the front interior lamp. The rear lamps illuminate at the same time as the front interior lamp.

Normal Operation

When any door is open, the door ajar switch closes and supplies a ground to the Generic Electronic Module (GEM). The GEM monitors the ajar circuits, and based on the ajar status, the GEM energizes the courtesy lamp relay, illuminating the courtesy lamps.

DTC DescriptionFault Trigger Conditions
B1319 - Driver Door Ajar Circuit FailureAn on-demand DTC that sets when the GEM detects an open from the driver door ajar input circuit.
B1327 - Passenger Door Ajar Circuit FailureAn on-demand DTC that sets when the GEM detects an open from the passenger door ajar input circuit.
B1335 - Door Ajar RR Circuit FailureAn on-demand DTC that sets when the GEM detects an open from the rear door ajar input circuit.
B1571 - Door Ajar LR Circuit FailureAn on-demand DTC that sets when the GEM detects an open from the sliding door ajar input circuit.

DTC DESCRIPTION CHART

This pinpoint test is intended to diagnose the following

  1. Wiring, terminals or connectors
  2. Door ajar switch
  3. GEM

The Generic Electronic Module (GEM) supplies voltage to the interior lamps through the battery saver output circuit. To control the illumination of the courtesy lamps, the GEM grounds the control side of the courtesy lamp relay located in the Central Junction Box (CJB). When the relay is energized, ground is supplied to the interior lamps.

The GEM monitors the door ajar switch status. When the doors are closed, the door ajar switches are open, removing ground to the GEM . When the GEM determines a door is open, the GEM then energizes the courtesy lamp relay to illuminate the interior lamps.

  1. DTC B1315 (Battery Saver Relay Coil Circuit Short To Battery) - a continuous DTC that sets when the GEM detects an open from the battery saver output circuit.
  2. DTC B1316 (Battery Saver Relay Coil Circuit Short To Ground) - a continuous DTC that sets when the GEM detects a short to ground from the battery saver output circuit.
  3. DTC B2555 (Dome Lamp Output Circuit Short to Battery) - a continuous DTC that sets when the GEM detects a short to battery from the courtesy lamp relay control circuit.

This pinpoint test is intended to diagnose the following

  1. Fuse
  2. Wiring, terminals or connectors
  3. Courtesy lamp relay
  4. Front interior lamp
  5. GEM

The Generic Electronic Module (GEM) supplies voltage to the interior lamps through the battery saver output circuit. To control the illumination of the courtesy lamps, the GEM grounds the control side of the courtesy lamp relay located in the Central Junction Box (CJB). When the relay is energized, ground is supplied to the interior lamps.

The GEM monitors the door ajar switch status. When the doors are closed, the door ajar switches are open, removing ground to the GEM . When the GEM determines a door is open, the GEM then energizes the courtesy lamp relay to illuminate the interior lamps.

This pinpoint test is intended to diagnose the following

  1. Wiring, terminals or connectors
  2. Courtesy lamp relay
  3. Door ajar switch
  4. Front interior lamp
  5. GEM

The Generic Electronic Module (GEM) supplies voltage to the interior lamps through the battery saver output circuit. When the front interior lamp control switch is in the ON position, the switch closes to ground illuminating the demand lamps.

This pinpoint test is intended to diagnose the following

  1. Wiring, terminals or connectors
  2. Front interior lamp

The Generic Electronic Module (GEM) provides a battery saver function. The battery saver function provides automatic shutoff of the interior lamps after 30 minutes has elapsed in order to save battery power.

  1. DTC B1315 (Battery Saver Relay Coil Circuit Short To Battery) - a continuous DTC that sets when the GEM detects a short to voltage from the battery saver output circuit.

This pinpoint test is intended to diagnose the following

  1. Wiring, terminals or connectors
  2. GEM

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