Wonky Headlight, do I need to replace?

[katozzi]

Hey ya'll, new here. I read some of the forums about the headlights costing upward of $1500 to replace, and wanted to see if anyone had dealt with what I am dealing with first before selling my firstborn son lol

We got a '21 Outer Banks model
I first noticed a problem when I locked the car at night. Usually the DRLs stay on for a minute or so to light my path, but the drivers side was out! So I went back to check. I started the bronco and turned on the DRLs and both were working... strange. Get out and lock, drivers side out.. head scratcher..

I drove home the next night and realized that the drivers side headlight wasn't working! The outer DRL ring was on, but both low and high beams are out on the drivers side. Again, when locking it, only the passenger side DRL stayed on, drivers was out. Is this a failure mode to tell the driver you have a headlight out?

So again, short of replacing the entire $1500 light, has anyone ever replaced just the LED Module Computer Light Control Unit? I found some on eBay for like $60 but wasn't sure if I'd be chasing my tail by purchasing something like this. Can you get just the headlight "bulb" without changing the entire unit?

Also, is it true that I'm gonna have to remove the whole front facia to get the headlight out? This stinks! Of course we are like 100 miles past warranty lol

Let me know if anyone has seen this issue before and what you did to solve it!

I'll also be sure to update as I fix, and include pictures and more details to come.

Thanks

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[katozzi]

This is the part I saw on eBay.

BTW, I think it would be worth noting, I am an Electrical Engineer for a OEM commercial Truck company, and I have some tools at my disposal that might help, but I still need some more info first.

Does anyone have access to a wiring diagram for how these headlights operate? I read that there is a LIN bus signal to the headlight controller module, but I'd like to see what pins they go to as I can take it apart and analyze the signals to further diagnose if its a controller or headlight issue. I have a bench power supply and proper leads that If I get the right pin, I can force 12V to the high beam pin to see if I get light.

Thanks

 

[Mrmike]

Contact me in conversations with your mailing address and I'll send you wiring diagrams.

 

[katozzi]

Updates:

I checked and we have no fault codes. I triple checked the 25A fuses and they are still good.

I did a silly thing and forgot to disconnect the battery while checking the fuses but then I noticed a strange phenomenon. If you are to remove the fuse box in the engine bay without disconnecting the battery, the headlights will go on, including my "broken" one! Meaning the "bulb" lighting element is still good. Small victories...
After re-connecting the fuse panel, the driver light goes back to its inoperable condition. If I unplug, and reconnect the drivers headlight connector, the headlight will illuminate briefly before turning back off again.
I disconnected the fuse box again, and then only the passenger headlight was on. Weird, because last time both were on.. Then I unplugged the passenger headlamp and the Drivers side turns on! Plug back in the passenger side and now they are both on! Great, both headlights are on, win! But then I reconnect the fuse box and then drivers side goes back off. SOaB!
This is so confusing lol.

So short of tracing signals, monitoring feedback voltages, and disassembling the light on a lab bench, I have no way of telling WHY the headlight turns off. I know now the lighting element is still functional, but there's a disconnect somewhere in the control circuit.

I hope to get my hands on a wiring diagram soon, and will update the chat as soon as I have a solution.

 

[Dude]

After you get access to the Bronco Sport wiring diagrams take a look at the diagram which looks like this attached pic and also there will be diagrams of the wiring harness to the headlamps.

Don’t use this specific pic as I believe it’s for the Bronco not the Bronco Sport (posted here just for example).

From descriptions of your troubleshooting, the BCM is suspected but you could also have a short in the wiring harness or a connector (I suspected the output FET is current limiting and shuts off (possibly explaining why both headlamps work sometimes, or possibly the FET might overheat and shut down).

Because you must be out of warranty and do not have Fords’s ESP with the Interior/Exterior Lighting rider you could continue diagnosing the issue after getting the wiring diagrams or contact a vehicle electrical repair shop specialist in your area.

 

[Dude]

Have you seen any evidence in or around your vehicle of rodents chewing wiring, building nests or unexplainable droppings?

 

[Dude]

If you could locate salvage Bronco Sports and if they have the complete working drivers side headlamp assembly for a reasonable price, possibly the first thing to try is to plug in this replacement but likely the harness connector isn’t long enough meaning you would need to disassemble your vehicle to install the replacement to see if putting in the replacement assembly solves the issue. Probably is a lot of work to do that and if nothing else you’d have a spare headlamp assembly if it was not the solution.

 

[katozzi]

Thanks, @Dude!

I haven't seen any evidence of chewed wires or live animals, but I suppose stranger things have happened.

Once I get the correct pinout of the headlight connector, I will probe the pin for low beam and see if I'm getting voltage there. Also, I will probe the LIN pin to see if I'm getting any COMS voltages.
-IF I have Comms, but no voltage on the low beam pin, then I'll trace back to the BCM.
-IF I have Comms, and I do have 12v on the low beam pin, but no headlight, I know its internal to the headlight and I'll have to remove to diagnose.
-IF I have no Comms on LIN pin, then I have to trace that wire back to check for damages. I'd be surprised if its damaged there would not be an DTC or error thrown when it can't communicate with the headlight. In the commercial truck world, we get error codes thrown when an ECU can't communicate to a module.

I'll post back once I have test results

Luckily we don't have to go anywhere at night for a while, and we have a backup car if needed.

 

[Dude]

Do u have the location for the BCM? I think I had read it takes some disassembly to locate it (IDK).

btw I think the headlamp unit is a sealed unit, I read was not serviceable - have you read anywhere that you can open up to service?

I’ve seen used headlamp units as low as $250 on Ebay.

 

[katozzi]

I have not located it yet. I am talking with an engineer who used to work at Ford and is familiar with the Bronco Sport, but didn't work on it specifically. Says it should be accessible under the glove box near the cabin air filter. I'll check after work.
Its either there, or inside the lower trim under the drivers footwell.

Anyone here have more specific info?

 

[Escape2Bronco]

I have not located it yet. I am talking with an engineer who used to work at Ford and is familiar with the Bronco Sport, but didn't work on it specifically. Says it should be accessible under the glove box near the cabin air filter. I'll check after work.
Its either there, or inside the lower trim under the drivers footwell.

Anyone here have more specific info?

If it's near the Cabin Air Filter, definitely check for rodent damage. They seem to have an affection for nesting on the cabin air filter. If they are nesting there, they may be going local for eats!

 

[katozzi]

I finally got to test the headlight connector today and got measurements for the pins. I don't know if the order is correct here, but if you reference the picture, I will go from top left to bottom right. (looking from inside the engine bay, out to the back of the light assembly)
Pin 2 = Turn signal
Pin 3 = Low Beam
Pin 4 = Constant 12v power
Pin 8 = Ground
Pin 14 = LIN Low (8V)
Pin 15 = LIN High

Pins 1, 5, 6, 7, 9, 10, 11, 12, 13, 16 are blank

I do have 12V at pin 3 when requesting low beams, and 12v is constantly present on pin 4. I have continuity to ground at Pin 8, and the LIN bus seems to be active. Turn signal is working as well and I can monitor the on/off cycle on my meter at Pin 2. So at this point I have no reason to believe that an external control source (BCM) is the culprit. I will have to disassemble the front end to get to the headlamp module in order to get to the heart of the issue.

I am still hesitant to replace the entire assembly as the DRL, and Turn still operate, and I was able to get the headlight low to illuminate briefly after reconnecting the PDM in the engine bay.

Stay tuned again as I try to get closer to the root of the headlight issues.

Please let me know if anyone has taken apart one of these headlamp assemblies before. If I am the first, then I'll document the best I can to help those in the future.

Thanks

 

[RSH]

Is your BS still under warranty?, if so I would take it in to the dealer and have them scan it to see what is causing the lighting fault and correcting it. While science projects can be fun, if you have any warranty left take advantage of it before it runs out.

 

[katozzi]

Is your BS still under warranty?, if so I would take it in to the dealer and have them scan it to see what is causing the lighting fault and correcting it. While science projects can be fun, if you have any warranty left take advantage of it before it runs out.

Unfortunately we were 50 miles over the warranty as of last service about a month ago. I may still go in to see if their scan tools detect this issue, as my basic scan tool does not. I'm assuming theirs has extra diagnostic capabilities that my amazon one doesn't.

 

[jzombie]

I had a huge issue with the 22C22 recall that dealt with the parking light issue. After it was done, the dealer didn't plug everything back in and then after they said they did I had the same issue you are explaining. then I turned it off and walked away, it was winking at me and if I locked/unlocked, there lights were never even in the front. I am not sure what all they did to fix it, but they did along with a bunch of other unrelated issues. I did notice that there's a dead spot now or maybe one of the headlights is misaligned. but they are at least on on both sides.

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