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Headlights quit working

I am the chief of a city fire department and I have a crew of full-time mechanics who maintain all our stations and equipment. I explained my problem to our mechanic that is the most-savvy "car computer geek". He suspected the cause after a very short explanation. He had dealt with a similar problem on a fire department Ford pickup with a snowplow. Almost identical symptoms after extra lights were added.

As has been suggested in this and other posts, the vehicle's many modules do all the work. The headlight switch, the high beam switch, the ambient light sensor, etc., all communicate to the Body Control Module (BCM) down near the steering column. The BCM actually controls the feeds to each headlight. It incorporates special circuitry that can sense overload and short-circuit conditions. It can disable the circuit temporarily (if the fault is intermittent) and restore it immediately. But apparently it keeps track of the occasions, and if it happens too often, it will shut the circuit down permanently and set a diagnostic trouble code (DTC). But most DTCs that occur in the Body Control Module will not illuminate the Malfunction Indicator Light.

So as I now know (and cited by other members) HID ballasts do indeed have a significant current draw spike at startup, and the BCM interprets that as an overload or even a "short to ground". I was on borrowed time feeding the ballasts directly off the headlight wiring (through a CANBUS adapter as originally recommended by TRS) so apparently the BCM counted enough occurrences and shut down the circuits, although not simultaneously as I mentioned earlier since it looks at each headlight feed separately.

The "fix" took all of 5 minutes. I borrowed our department's Snap-On scan tool, plugged it in, saw the codes showing both right and left headlights had a "short to ground". I then told the scan tool to clear the codes, and instantly the headlight circuits were restored! I hooked up my newly-acquired TRS relay kit and everything is back to normal. What a relief! I hope and believe everything should work properly from now on since all ballast current is coming directly from a battery feed via the relays. There is actually only a very small current draw coming only through the left headlight circuit to activate the relays.

Understanding what has happened (and how to remedy it) has again made me comfortable with my upgrade. I can tell you the lighting difference from the stock halogen projectors to the Evo-X units with Phillips D2S HID bulbs is nothing short of amazing. I never tried placing HID bulbs directly into the stock (halogen) projectors, but others have attested that even that is much better output than stock. I reiterate that Ford should have made HID an option on the Sport, but according to some (so-called) experts, my projectors have better optics than what does come on Limited Explorers with HID. Never done a side-by-side comparison, no one I know has such a vehicle.

I would have happily paid for factory HIDs had they been available...

I would have too, but this is exactly why I did not want to buy aftermarket HID's...

I hope you get this worked out !!

Many of us have installed aftermarket high quality HID kits with relays and had no issues at all. My Diode Dynamics kit came with HYLUX CANBUS ballasts, relay kit, DRL relay,and I have never had an issue plus they run as DRL's all the time. Looks completely stock beside a Limited with HID's.