Weird Headlight Trick
Thread Starter
|
New User
Joined: Oct 2009
Posts: 20
Likes: 0
Weird Headlight Trick
My 2006 Ford F250 SC LWB 4x4 has developed an unusual electrical problem. If I have the headlights on manually with the engine running and turn off the key, the engine continues to run. Also, all of the "dummy" lights in the gauge cluster light up as if I had just turned the key to "on." If I shut off the headlights, the engine shuts down and the gauge lights go out. Conversely, if I have the headlights on "Auto," it does not have any problems. Have you guys heard of this before? Thanks for the help.
Lead Driver
Joined: Jul 2003
Posts: 7,406
Likes: 52
From: Wheatland, Mo
That does sound like a wierd one but it could also be some sort of custom "Valet" or "Warm-up" mode. The dash lights would be how it tells you you are in this mode so you don't try to drive off with the keys not in. Most valet modes or warmup modes like that will kill the engine if you step on the brake when it is in place, which needs to be done to put it into gear. Kind of like a safety feature. But put the key in and turn to RUN, the lights on the dash go out and away you go. Something to look into.
And the headlights on from the outside tell you it is running in this mode.
And the headlights on from the outside tell you it is running in this mode.
Thread Starter
|
New User
Joined: Oct 2009
Posts: 20
Likes: 0
I appreciate the response. I recently found out about the problem after I drove a half hour into town with my headlights on. The engine was fully warm. I depressed the brake, placed the transmission in park, and then removed the key. The engine kept running after the key was removed. I heard a warning chime and all of the gauge warning lights lit. When I heard the chime, I automatically thought about the headlights. When I switched them off, the engine shut down and the gauge lights went out. I did buy this truck used. So, it is possible that there is aftermarket equipment in the dash. It still seems a little unusual. Any ideas on what could be causing the engine to keep running?
Lead Driver
Joined: Jul 2003
Posts: 7,406
Likes: 52
From: Wheatland, Mo
I am thinking it is supposed to do that. So you can keep the truck running and let it warm up without having to sit there with it and you can lock the doors and walk away. I would drop the lower dash panel and look for a module with a harness attached to it that isn't a factory module.
What happens when you hit the brakes with the key out and the engine still running?
What happens when you hit the brakes with the key out and the engine still running?
Prolocutor
Joined: Jan 2009
Posts: 13,618
Likes: 1,247
From: Western MA
I just looked up the manual remote start. It works like this.
to arm the system you:
parked
put car in neutral
set e-brake
push button on key fob
remove key from ignition (vehicle continued to run)
got out
locked door (vehicle quit)
If you have an auto, ignore this. It is just a thought.
to arm the system you:
parked
put car in neutral
set e-brake
push button on key fob
remove key from ignition (vehicle continued to run)
got out
locked door (vehicle quit)
If you have an auto, ignore this. It is just a thought.
Thread Starter
|
New User
Joined: Oct 2009
Posts: 20
Likes: 0
My truck is an automatic with factory keyless entry (advanced security group).
BillyBob69: I will try it again this evening, but I believe that the engine kept running with the headlights on, key out, and the foot on the brake. I will check it out and get back to you later tonight.
I will also look in the dash for aftermarket modules. Thanks for the help.
BillyBob69: I will try it again this evening, but I believe that the engine kept running with the headlights on, key out, and the foot on the brake. I will check it out and get back to you later tonight.
I will also look in the dash for aftermarket modules. Thanks for the help.
Trending Topics
Thread Starter
|
New User
Joined: Oct 2009
Posts: 20
Likes: 0
I drove the truck last night and figured out some more information. The problem happens when I have the headlights and fog lights on simultaneously. When the headlights and fog lights are on and the key is removed, the engine continues to run. When I turn off the fog lights (with the headlights still on), the engine shuts down. When I pull the fog light switch back out, the dummy lights come on as if the ignition is in the "on" position. Has my truck been modified to do this amazing trick, or is it an electrical issue? Thanks.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
Cargo Master
Joined: Jun 2008
Posts: 2,752
Likes: 5
From: Stillwater, OK
I wired an accessory wire to my 1977 C-10 once...
I wanted the radio to come on with the ignition, and to come on with a toggle switch.
I found out one day, that if I turned the toggle switch on with the engine running, it would backfeed through the radio and keep the ignition hot...
solution: I put a diode in the line between the ignition line and the radio so power could only go one direction.
theory: find out if those fog lights are factory, aftermarket, or modified... I'll bet somebody jumped a wire to the relay from the wrong circuit, and when the fogs are on, they backfeed to your ignition.
I wanted the radio to come on with the ignition, and to come on with a toggle switch.
I found out one day, that if I turned the toggle switch on with the engine running, it would backfeed through the radio and keep the ignition hot...
solution: I put a diode in the line between the ignition line and the radio so power could only go one direction.
theory: find out if those fog lights are factory, aftermarket, or modified... I'll bet somebody jumped a wire to the relay from the wrong circuit, and when the fogs are on, they backfeed to your ignition.
Thread Starter
|
New User
Joined: Oct 2009
Posts: 20
Likes: 0
Thanks for all of your help. They are factory fog lights, but the truck was purchased used and possibly modified. I will trace the wires to see where the power is leaking from. I appreciate the advice.
Hotshot
Joined: Aug 2006
Posts: 17,398
Likes: 317
From: Whittier, CA
I've been following along on this because it is an interesting problem. I think you guys have it narrowed down to backfeed.
All I can add is this. With the truck running, turn on your headlights and fog lights. Then turn on your bright headlights. Your fog lights should go off, because Ford designed it so that brights and fogs cannot be on simultaneously. If your fogs stay on, someone modified it to do that. It's a common complaint and a common modification that could easily be done in an incorrect manner.
All I can add is this. With the truck running, turn on your headlights and fog lights. Then turn on your bright headlights. Your fog lights should go off, because Ford designed it so that brights and fogs cannot be on simultaneously. If your fogs stay on, someone modified it to do that. It's a common complaint and a common modification that could easily be done in an incorrect manner.
Thread Starter
|
New User
Joined: Oct 2009
Posts: 20
Likes: 0
Thank you bpounds and all of the other contributors to this thread. Initially, I was baffled that my truck kept running without the key. Your comments made me realize just how simple the problem really was. Thanks again!
