I was driving and smelled an electrical burning in the cab then the Cargo Lamp On displayed in the message center and the courtesy lights stopped working. I replaced the courtesy light fuse under the hood and It was blown immediately. I removed the inadvertent relay and the fuse did not blow. I tested both the inadvertent relay and courtesy lamp relay and they test good pulling 1.6 amps at 12 volts defiantly under the 10 Amp fused rating. I pulled all lamps which still blows the fuse, but now the Cargo Lamp on does not display in the message center until the switch is on. I would hate to believe it is the Body Control Module but that is all after I check for shorted wires. And why would it be a BCM only pull enough current to blow the 10 A fuse when the inadvertent relay was in the circuit which only pulls 1.6 amps?

Interior Lamps
The interior lighting consist of the following 2 groups. This first group includes lamps that may not be dimmed.
• The cargo lamp
• The dome lamps
• The reading lamps
• The vanity mirror lamps
Courtesy Lamps
The courtesy lamps include the reading lamps, cargo lamp, and dome lamps. The cargo lamp and dome lamps may be manually turned ON or OFF by placing the interior lamp switch in the ON or OFF position. When the driver places the dome lamp defeat switch in the OFF position, these courtesy lamps will be disabled. If a door is opened, the courtesy lamps illuminate. After all the doors have been closed, the courtesy lamps will remain illuminated approximately 15 seconds after the last door closes. The courtesy lamps will also turn ON prior to any door being opened and will remain illuminated approximately 40 seconds when the driver removes the ignition key. The body control module (BCM) will immediately turn OFF the courtesy lamps if a door lock command is received with all of the doors closed, or if the ignition switch is turned to either the ON or RUN position.


These lights ?

Vanity Mirror Lamps
The inadvertent power courtesy lamps supply voltage circuit of the body control module (BCM) provides battery positive voltage to each vanity mirror lamp. When the vanity mirror cover on the sunshade is opened, a switch closes to provide a ground circuit and the vanity lamp illuminates.
Battery Rundown Protection/Inadvertent Power
The body control module (BCM) inadvertent power courtesy lamps supply voltage circuit provides battery positive voltage to all of the interior reading lamps and both visor vanity mirror lamps. In the event that any of these lamps were to remain illuminated for a period of more than 20 minutes with the ignition switch in the OFF position, the BCM will deactivate the inadvertent power courtesy lamps supply voltage circuit to prevent a total battery discharge condition. Only when the ignition switch is cycled back to the RUN position will the BCM reset the internal timer and reactivate the inadvertent power courtesy lamps supply voltage circuit.
The BCM also utilizes the inadvertent power courtesy lamps supply voltage circuit as a courtesy lamp request signal circuit when none of the lamps in the circuit are illuminated. When a lamp switch is activated, the BCM receives the request for lamp illumination and switches to supplying voltage to the inadvertent power courtesy lamps supply voltage circuit.

Check fuses under the hood on driver side

Chevrolet 1977 And 1980 C and K Model Fuse Blocks

(The numbers, eg; "UF2" Cargo Area Lamp, are RPO numbers.)

A - Fuse - Traffic Hazard

B - Fuse - Tail, Stop Courtesy Lamps

C - Receptacle - TP2 /M40

D - Fuse - Radio & TCS

F - Receptacle - C91/UF2 (Cargo Area Lamp)/U35/U37

G - Fuse - Heater / Air Cond.

H - Receptacle - C62

I - Fuse - Accessory

J - Fuse - Panel Lights

K - Receptacle - NL2/A33/U16 (Tachometer)

M - Receptacle - Accessory Lamps

N - Not Used

O - Fuse - Reversing Lamps

P - Fuse - Instrument Cluster Feed

Voltage to the coil of the courtesy lamp relay, dome, reading lamp, courtesy lamps, cargo Lamp, instrument panel (IP) compartment lamp and the underhood lamp is supplied from the Inadvertent power relay on CKT 1732. The inadvertent power relay receives voltage from the CTSY LP fuse which is hot at all times. Ground for the courtesy lamps goes through the courtesy lamp relay. Both relays are controlled by the body control module (BCM) based on inputs from door jamb switch, dome lamp switch or door handle switch. The BCM will supply a ground to the courtesy lamp relay when closing any one of the above switches to ground. Ground for the reading lamp, cargo lamp, IP compartment lamp and the underhood lamp is supplied by its own ground.

Interior lights blink off and on ????? As in dome lamps, dash light's etc...??? An what the heck is this mean We were told to hinge the module?????? I have been an automotive technician over 30 yr's an never heard the term hinge the module. The interior lighting on your vehicle is controlled by the smart junction box , ford's BCM body control module . ( Electronic's ) Who checked the vehicle ? Dealer ?
Interior Lighting The interior lighting system consists of the following:

• Smart junction box (SJB)
• Interior/map lamp assembly
• Rail lamps (if equipped)
• Glove compartment lamp assembly
• Dimmer switch
• Illuminated vanity mirrors (if equipped)
• Rear cargo lamp
• Puddle lamps (if equipped)
• Door ajar switches
• Liftgate glass ajar switch

The interior lighting system consists of 2 subsystems:

• Courtesy lamps
• Demand lamps

The courtesy lamps are controlled by the SJB. The courtesy lamp subsystem consists of the ajar switches, the interior dome lamps, the puddle lamps, the roof rail lamps, the cargo lamp, and the overhead console lamps (if equipped). The SJB supplies voltage to the courtesy lamps when the SJB receives the required input.
The demand lamps subsystem consists of the glove compartment lamp, the dimmer switch, the cargo lamp, all map/reading lamps, the roof rail lamps, and the LH and RH vanity mirror lamps.
The SJB supplies power to the interior lighting system. The SJB sets DTCs if certain circuit failures exist with the interior lighting system.
Visual Inspection Chart Mechanical Electrical

• Courtesy lamps
• Map lamps
• Vanity lamps
• Door ajar switches

• Smart junction box (SJB) fuse(s):
  • 9 (15A)
  • 10 (15A)
  • 25 (10A)
• Circuitry
• Courtesy lamps
• Map lamps
• Cargo lamps
• Vanity lamps
• Glove compartment lamp
• Dimmer switch
• SJB

1. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.

1. NOTE: Make sure to use the latest scan tool release software. If the cause is not visually evident, connect the scan tool to the data link connector (DLC).

1. NOTE: The vehicle communication module (VCM) LED prove-out confirms power and ground from the DLC are provided to the VCM. If the scan tool does not communicate with the VCM:
   • Check the VCM connection to the vehicle.
   • Check the scan tool connection to the VCM.
   • Refer to Section 418-00 , No Power To The Scan Tool, to diagnose no communication with the scan tool.

1. If the scan tool does not communicate with the vehicle:
   • Verify the ignition key is in the ON position.
   • Verify the scan tool operation with a known good vehicle.
   • Refer to Section 418-00 to diagnose no response from the powertrain control module (PCM).

1. Carry out the network test.
   • If the scan tool responds with no communication for one or more modules, refer to Section 418-00 .
   • If the network test passes, retrieve and record the continuous memory DTCs.

1. Clear the continuous DTCs and carry out the self-test diagnostics for the SJB.

1. If the DTCs retrieved are related to the concern, go to the Smart Junction Box (SJB) Diagnostic Trouble Code (DTC) Chart or the Power Liftgate Module Diagnostic Trouble Code (DTC) Chart. For all other DTCs, refer to Section 419-10 .

1. If no DTCs related to the concern are retrieved, GO to Symptom Chart .

Smart Junction Box (SJB) Diagnostic Trouble Code (DTC) Chart DTC Description Action B1320 Driver Door Ajar Circuit Open Go To Pinpoint Test C . B1328 Passenger Door Ajar Circuit Open Go To Pinpoint Test C . B1331 Decklid Ajar Rear Door Circuit Failure Go To Pinpoint Test C . B1336 Door Ajar RR Circuit Open Go To Pinpoint Test C . B1572 Door Ajar LR Circuit Go To Pinpoint Test C . B1688 Lamp Dome Input Circuit Short to Ground Go To Pinpoint Test C . B2077 Liftgate Ajar Circuit Failure Go To Pinpoint Test C . B2A35 Interior Lighting Output Circuit Open If the courtesy lamps are inoperative, Go To Pinpoint Test A .
If the courtesy lamps stay on continuously, Go To Pinpoint Test C . B2A36 Interior Lighting Output Circuit Short to Ground Go To Pinpoint Test A . B2A39 Puddle Lamp Output Circuit Open Go To Pinpoint Test J . B2A3A Puddle Lamp Output Circuit Short to Ground If the puddle lamps are inoperative, Go To Pinpoint Test J .
If the puddle lamps are always on, Go To Pinpoint Test L . All other DTCs - REFER to Section 419-10 .

Cargo light is on the back of the cab to shine on your cargo, in the bed.

The SJB supplies power to the interior lighting system. The SJB will set DTCs if certain circuit failures exist with the interior lighting system.
Visual Inspection Chart Mechanical Electrical

• Courtesy lamps
• Map lamps
• Luggage compartment lamp
• Vanity lamps
• Glove compartment lamp

• Smart junction box (SJB) fuse 3 (15A)
• Circuitry
• Courtesy lamps
• Map lamps
• Luggage compartment lamp
• Vanity lamps
• Glove compartment lamp
• SJB

Check fuse # 3 SJB

From the Owners Manual, check position 14, 10AMP (Dome Lamp, Cargo Lamp, Courtesy Lamps, Running Board Lamps) in the Passenger Compartment Fuse Panel.

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Your courtesy fuse is blown. Look under the hood fusebox. There should be a fuse labeled CTSY (10amp). If blown, you have a hot wire touching bare metal.

Check under the hood, in the fusebox, for a fuse label ctsy (courtesy). It'll be over the driver side wheel. Replace it, if blows and, you have a wire touching bear metal somewhere. Good luck!