Fog lights will not turn on?

Hello,

It sounds like the BCM has gone out but to be sure lets check the fuses that run the system, #16, 17, 39, 23 and 24. Here is a guide to help us get started and the wiring diagrams for you to see how the headlight system works and the fuse location and BCM location below.

If the BCM is bad it will need to be programmed in which will run about $130.00.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Removal

NOTICE: Electronic modules are sensitive to static electrical charges. If exposed to these charges, damage may result.

NOTE: Prior to the replacement of the Body Control Module (BCM) , it is necessary to upload the module configuration information to the appropriate scan tool. This information must be downloaded into the new BCM (Body Control Module) after installation. In the event that As-Built data entry is required (BCM (Body Control Module) will not communicate), all Integrated Keyhead Transmitters (IKTs) devices must be programmed. A minimum of 2 devices are necessary to complete the configuration and turn off the flashing interior lights.

1. NOTE: This step is necessary only if the BCM (Body Control Module) is being replaced.
NOTE: If installing a new BCM (Body Control Module) , all vehicle keys are erased during the parameter reset procedure. Verify at least 2 of the vehicle keys are available prior to carrying out this procedure.
Upload the module configuration information from the BCM (Body Control Module) .

2. Remove the passenger cowl side trim panel.

3. NOTE: The upper 12A581 harness BCM (Body Control Module) (B+) connector may be more easily removed after the BCM (Body Control Module) brackets and bolts are removed and the BCM (Body Control Module) can be positioned lower and away from the body in order for the connector release tangs to be accessed and pressed.
Disconnect the 7 BCM (Body Control Module) electrical connectors.

4. Remove the in-line connector wiring harness push pins (2) from the BCM (Body Control Module) .

5. Remove the 2 bolts and the BCM (Body Control Module) .

6. Remove the BCM (Body Control Module) front bracket and the 2 BCM (Body Control Module) brackets from the BCM (Body Control Module) .

Installation

1. Install the 2 bolts and the BCM (Body Control Module) .
- Tighten to 2 Nm (18 lb-in).

2. Install the in-line connector wiring harness push-pins (2) on the BCM (Body Control Module) .

3. Connect the 7 BCM (Body Control Module) electrical connectors.

4. NOTE: If the BCM (Body Control Module) was not replaced, this is the last step that is necessary.
Install the passenger cowl side trim panel.

5. NOTE: Once the BCM (Body Control Module) Programmable Module Installation (PMI) is complete, follow the scan tool's on-screen instructions for performing the Configured Engine Immobilizer (CEI) Lock Configuration.
Download the BCM (Body Control Module) configuration information from the scan tool.

6. NOTE: If a new BCM (Body Control Module) is installed, the BCM (Body Control Module) and the PCM require a parameter reset to allow the BCM (Body Control Module) and the PCM to recognize each other.
NOTE: If equipped, the vehicle's IKTs (Integrated Keyhead Transmitters) must be programmed to the new BCM (Body Control Module) .
If installing a new BCM (Body Control Module) , carry out the parameter reset and key programming procedure. For additional information, refer to Antitheft and Alarm Systems.

7. Carry out the BCM (Body Control Module) on-demand self-test to confirm all DTCs have been cleared.

Check out the diagrams (below). Please let us know what you find. We are interested to see what it is.

Check items in pic like grounds etc. It may be a broken or shorted wire or bad connection at relay, try some dielectric grease on prongs of relay about $2 on counter at auto parts.

This problem could be the switch, can you please re-upload the pic harry? It didn't show up

I either forgot or another problem

Have you checked for power and ground at the bulb, here is a guide it is for the rear lights but your problem follows the same method.

https://www.2carpros.com/articles/no-tail-lights-exterior-running-lights-tail-lights-out

Let me know what you find

Originally I sent a pic that didn't show up the fog lights operate off the same relay etc. You had stated that the one side worked which in the pic both operate off the same relay so it could be a wiring issue like shorting out or partially broken between LH and RH sides. So make sure to check that. The smart box problem I thought was limited to expeditions but not really sure. It is 2003-06 that have that problem and it's normally the fuel pump circuit that screws up, not the lights. So check the wiring in the pic as it may have a problem there it is the same color on both sides. Also check the grounds as they are separate and could be the problem for one light.

Your dandy observation that the relay clicks proves everything in the first diagram and everything left of the red line in the second diagram is working. That leaves very little. The tan / orange wire, circuit 478, is in common with both lights, but the better suspect would be a corroded ground, G103.

The third drawing is for the 4.6L engine, but G103 is listed as, "right front radiator support" for all engines.

If the ground looks okay, turn the fog lights on, then take voltage readings at one of the bulb sockets. One must have 12 volts. If it's missing, check fuse 9 in the under-hood fuse box.