2015 Low Beam headlights won't turn on

[feelthemusic8]

My Low Beam headlights will not turn on at all on my 2015 Expedition.


- High Beam headlights work normally

- Fog Lamps work normally

- Problem occurs on all headlamp settings, auto lamp, fogs on and off, etc

- Problem occurs on both right and left lamps

- Headlamps are plug and play HID high and low bulbs


So far I have done these steps in this order:


- Changed bulbs to new HIDs

- Changed ballasts to new ballasts

- Checked both left and right fuses for low beams (they were fine)

- Changed both fuses with new fuses

- Removed Low beam HIDs on both sides and replaced with the original factory Bulbs (Halogen)

- Replaced Entire Headlamp switch on the lower dash

- Replaced Multi Function Switch on the Steering Column


After all this, I still have no working low beam headlights. At this point, I have the stock halogen bulbs, all new switches and fuses. I have also checked all wiring and connectors at and near each of these parts and everything looks normal with no corrosion, melting etc. Also have no other electrical issues in the vehicle.


The only other related thing that seems like it could have been related is that I originally noticed the problem, but if I switched the headlights off and back on a few times, they would come on. After I changed my battery recently, that trick no longer worked.


Any ideas?

 

[Bedrck47]

At no time in reading your post have I noticed if you made any voltage checks

 

[feelthemusic8]

Exactly where would I checked the voltage?

 

[99WhiteC5Coupe]

I have a 2015 Expedition Limited 4x4, purchased new. Halogen projector headlamps were standard. HID lamps were not offered.

Have you altered the original lighting? If so, why don't you contact the manufacturer of the aftermarket parts that you installed?

Perhaps you could return the headlamps to the original "stock" system?

 

[Bedrck47]

At the low beam lamp socket see if you have 12 volts when you turn the low beams on.

Also check to see if you have voltage into and thru the fuses.

I don't have prints for the 2015 model but looking back to some older models 09/10 Ford now uses FET's (field effect transistors) which are part of the fuse box to provide voltage to the lights. This could be your problem and I would think that the fuse box would need to be replaced.

I normally don't like to make a guess on these problems But in this case that would be my best guess.

 

[stamp11127]

With all the electronics on vehicles of today, the wiring diagrams are a must have if you are trouble shooting the electrical system.

We now have computer control over what used to be a simple circuit. If the computer or microprocessor senses a problem on a circuit, it may have an algorithm it follows before shutting down that circuit. Prior to replacing parts it is best to prove the part in question has indeed failed. In your case it is possible that the fuse box is fine but the problem is in the harness. You will need the diagrams, pinouts of the connectors and a multimeter to locate the problem.

 

[feelthemusic8]

I have a 2015 Expedition Limited 4x4, purchased new. Halogen projector headlamps were standard. HID lamps were not offered.

Have you altered the original lighting? If so, why don't you contact the manufacturer of the aftermarket parts that you installed?

Perhaps you could return the headlamps to the original "stock" system?

Yes I have the exact same vehicle. Like I said in the post, I used plug and play aftermarket HIDs, which I subsequently replaced with my factory halogen, after two sets of HIDs failed to work. I did not alter any wiring. The factory bulbs are not working either.

 

[feelthemusic8]

With all the electronics on vehicles of today, the wiring diagrams are a must have if you are trouble shooting the electrical system.

We now have computer control over what used to be a simple circuit. If the computer or microprocessor senses a problem on a circuit, it may have an algorithm it follows before shutting down that circuit. Prior to replacing parts it is best to prove the part in question has indeed failed. In your case it is possible that the fuse box is fine but the problem is in the harness. You will need the diagrams, pinouts of the connectors and a multimeter to locate the problem.

Luckily I do have the diagram. It is what I used in my troubleshooting to this point. I'll attach it here. Let me know at which point I should be checking the voltage.

 

[feelthemusic8]

At the low beam lamp socket see if you have 12 volts when you turn the low beams on.

Also check to see if you have voltage into and thru the fuses.

I don't have prints for the 2015 model but looking back to some older models 09/10 Ford now uses FET's (field effect transistors) which are part of the fuse box to provide voltage to the lights. This could be your problem and I would think that the fuse box would need to be replaced.

I normally don't like to make a guess on these problems But in this case that would be my best guess.

Can you tell from the diagram, if the FETs are being used in this model and if so how would I test that?

 

[stamp11127]

Yes they are using FET's. Look at the top of the diagram at the large box labeled "body control module (bcm)". Within that box are circles labeled FET for each high/low head lamp.
Word of warning here - there are also two wires that connect to the Can (data network - computer data lines). Do not apply power to any of the pins in the connectors while connected to the bcm - that means checking continuity using the meter. You can only test for power output, not continuity. The meter supplies power in that mode.
First step is to check power in and out of fuses 16 & 17 with a meter set on 12v DC or a test light. That bus is "hot at all times" so you don't have to turn the ignition on.