Weird Electrical Issue

justinlogue5_0 · Mar 11, 2026

New to me 11/2000 F350 Auto, less than 200 on the clock. When you first crank the truck, if you immediately turn on the headlights (not the marking lights) the truck instantly dies as if you hit a kill switch. Turn lights off and repeat, same thing. If you turn on headlights first then crank truck its fine. If you crank truck and let it get up to normal temperature then turn on the headlights it works fine. Previous owner installed newer headlights from a 6.0 truck (can't remember which actual year) , along with HID bulbs. Factory plug goes to a "transformer" and then from it to the bulb. Due to some weird other issues I have replaced the ICP, PCM, Hydra chip, new tunes from different tuner, and the upgraded RiffRaff CPS. The truck runs,idles, and drives great now but as stated I am still dealing with the headlight issue. Any one seen this? Thanks

6.0 Tech · Mar 11, 2026

What’s voltage at when it first fires? Could the hids be pulling voltage below 10ish volts? Like bad battery or both, or a lazy alternator?

Tiha · Mar 12, 2026

Kind of wondering where he tapped in the relay or transformer for the headlights.

On warm up, Could it be tied to the glow plug circuit? So like when the glow plugs are finally done cycling then there is enough left to keep the ignition on?

Maybe another thing to try is unplug the headlight bulbs and try with the rest of the marker lights on? make sure we are blaming the correct thing?

justinlogue5_0 · Mar 12, 2026

The truck has new batteries (and starter) and according to the digital volt gauge on the Edge the voltage never dropped below 11.5 when cranking. If needed I can double check those readings with a multi meter this week end. After glow plugs are done with there cycle and the voltage climbs back to normal I am showing 14.1. I can unplug the headlight ballasts this weekend and try it (no time in the mornings during the week) to see if something else is actually causing the issue and the headlights them selves is just something I can see. On a side note if you google this symptom one of the possibilities is a shorted out/going bad headlight switch? I think google thought more of a no crank at all while headlights are on BUT I went ahead and ordered one just to make sure. The original switch is old and the knob does (in my opinion) have some play in it so when the new one gets here I will see if that changes anything.

Side question regarding the wiring of the headlights. I will have to double check since I am not experienced in HID lights but I thought all the power comes from the bulb pigtail plugging into the ballast, then the ballast sends power to the bulb in its own pigtail? I don't think there is any other power wires that could get plugged into the glow plug wires? I will go out and double check that on my lunch break.

TD-5 · Mar 12, 2026

On a cold start the Glow plugs stay activated for up to 1- 2 min after the engine starts. During this time the ECM does not allow the alternator to charge so only battery voltage is available. If the HID lights are activated during this period it's possible they are causing a large enough voltage drop when they first fire to cause the ECM to drop out and shut the engine off.

Tiha · Mar 13, 2026

justinlogue5_0 said:
Side question regarding the wiring of the headlights. I will have to double check since I am not experienced in HID lights but I thought all the power comes from the bulb pigtail plugging into the ballast, then the ballast sends power to the bulb in its own pigtail? I don't think there is any other power wires that could get plugged into the glow plug wires? I will go out and double check that on my lunch break.

Correct, most aftermarket bulbs use the factory wiring, but if the dude was having issues there is no telling what they did.

I have seen aftermarket kids melt wires and plugs quite often. So maybe he did something stupid to work around that.

Don't know, just throwing ideas out there in hopes you get it fixed.

Tiha · Mar 13, 2026

Do you have auto headlamps, and/or daytime running lamps?

Just went through my wiring diagrams. The only place the headlamp system and ignition system is really in the Fuse box, or what they call central junction box. I wonder if you have a bad connection in there, where as it cannot handle the load with everything on.

no idea what circuit it would be though. Anything else not working that you notice?

justinlogue5_0 · Mar 13, 2026

I think you may me on to something about the extra draw while glow plugs are on. Here is an update, checked head light wiring and there is a relay of sorts for the headlight "kit". The relay is grounded to the body ground and the power wire goes straight to the DS battery and the wiring splits off and goes over to the PS headlight ballast. Then as described the factory headlight pig tail plugs into the ballast and then from there to the bulb. So it looks like the head light pigtail is the trigger wire turning on the relay to the ballast and then the ballast feeds the head light bulb.

New headlight switch came in day early BUT was wrong one so back to waiting on the correct one but I don't think that is the issue since I was able to see this when I cranked it this morning, which was I left the lights off and cranked the truck "11.7v" and holding. Once the dome light got brighter and I started to see the Volts climb I knew the glow plugs were done so I flipped on the head lights and the motor never missed a beat! Couple days ago I got in the truck (weather was in the low 70's so not hot) drove about 5 mins up the road and shut it off for about 15 mins to run an errand. Cranked the truck turned on the lights and as expected it killed the truck BUT if the oil wasn't warm enough the glow plugs might have been on still and I didn't realize that was what was going on, I will have to watch this closer now. Remind me again, don't the glow plugs keep working until the truck sees 130* (+/-) oil temp then the truck doesn't turn on the glow plugs anymore?

If this is the case I just learned something new! I knew if the batteries were weak and the motor could turn at least 500 to 600 rpms the truck would never crank but I didn't know the low power would straight up kill the truck.

Anyways I will pay closer attention to the volts as I turn on the lights. I like how bright they are but I may change them out. This could be annoying at times.

justinlogue5_0 · Mar 13, 2026

Tiha said:
Do you have auto headlamps, and/or daytime running lamps?

Just went through my wiring diagrams. The only place the headlamp system and ignition system is really in the Fuse box, or what they call central junction box. I wonder if you have a bad connection in there, where as it cannot handle the load with everything on.

no idea what circuit it would be though. Anything else not working that you notice?

No on the auto or daytime running lights. The headlight kit has a small inline fuse as well but I think TD-5 is on to something, see what I just posted for the full story. Thanks!

TD-5 · Mar 13, 2026

On my 97 I've always watched the voltmeter on the dash, It will take a dip when the key is first turned to on and then not move up to the normal position until the glow plugs finish their cycle after the truck is started. It's always been a good visual indicator of what the glow plug circuit is doing.

justinlogue5_0 · Mar 13, 2026

I knew it dipped and was used to it, I just never knew the HID's would pull that much power when turning them on to kill the truck. The relay wires are so small on this kit I don't see how they pull any power at all, lol. My E99 was reg lights, My 02 was LED with no issues, now this truck has the HID and again I never would have thought it pulled that much. Like I said, learned something new Thanks for the help!

justinlogue5_0 · May 21, 2026

Update: Its doesn't kill the engine anymore since I wait for the glow plugs to def shut off and voltage to climb back up BUT I have noticed a new issue. While driving down the interstate I flashed my lights to let a semi know he can come over and when I did it actually "hiccuped" the motor. It didn't die but it made all the idiot lights come on as if I just turned the key on, also kicked off the cruise control. When I got home I tried to replicate the issue ans I was only able to get it to verily stumble (almost not noticeable) one more time. Tried flashing them slow, fast ect... and nothing happened. Do I have something else going on or do these fancy headlights just pull that much power? If so I would rather just use regular headlight bulbs rather than deal with this issue?