Headlights come on with parking lights
#1
06-15-2010, 06:06 PM
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Headlights come on with parking lights
I recently discovered that I am having electrical issues. I did the parking light fog light mod when I bought the truck in 02, and everything has been working fine since.
But today I noticed that when i switch the parking lights on, the headlights come on also. Can one of you experts help me diagnose this?
Truck is an 02 lariat 4x4 ext cab.
I know its not the switch assembly, because I switched it out with my roommate's headlight switch, and it did the same thing. I believe it is either a short, or a relay. I would like to know the most probable location of the short, or just where the wires are located to start looking, and also which relay to check.
The headlight seem to get just a little bit brighter when I flip the switch from parking lights to headlights.
Thanks very much for any help you can offer.
But today I noticed that when i switch the parking lights on, the headlights come on also. Can one of you experts help me diagnose this?
Truck is an 02 lariat 4x4 ext cab.
I know its not the switch assembly, because I switched it out with my roommate's headlight switch, and it did the same thing. I believe it is either a short, or a relay. I would like to know the most probable location of the short, or just where the wires are located to start looking, and also which relay to check.
The headlight seem to get just a little bit brighter when I flip the switch from parking lights to headlights.
Thanks very much for any help you can offer.
#2
06-15-2010, 06:38 PM
When you did the modification, did you removed the CJB ( aka Central Junction Box / cab fuse ) Fuse #27 ?
If you press the fog lamp switch in, while the headlamp switch is in the park position, the headlamps go off, or if you push the MFS forward ( so the high beams are on ), same thing, the headlamps go off ?
If you press the fog lamp switch in, while the headlamp switch is in the park position, the headlamps go off, or if you push the MFS forward ( so the high beams are on ), same thing, the headlamps go off ?
#3
06-15-2010, 08:36 PM
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I removed fuse #27 and it works again. Wow. You are a master of the wiring schematic. The fuse must have been blown for quite some time without me knowing. I had just replaced it today, because I hooked up to a trailer with a short. I found two fuses that were blown, the first being #27, and the second being one of the 20 amp fuses under the hood. I forget the number... Forgive my curiousness, but would the fog lamp splice mod cause the 5 amp fuse to blow? I am just wondering if it was blown for the last 8 years, and I never noticed it. Your knowledge of the wiring in these Fords is mind blowing to me. Thanks very much for the help!!!
#4
06-15-2010, 10:45 PM
It should blow, you are trying to power both low beams via this 5 A fuse.
The reason they were dim with the main headlamp switch in the park position is you were powering both headlamps via this fuse and the splice.
This is one thing missing from all the directions on doing the fog lamp mod, and most are in the same boat ( no pun intended ) as you, they do the mod, and turn on the parking lamps, and most might not notice the 1st few min, the headlamps are on. Others the fuse could blow very quick, and it is a flash of light.
The reason they were dim with the main headlamp switch in the park position is you were powering both headlamps via this fuse and the splice.
This is one thing missing from all the directions on doing the fog lamp mod, and most are in the same boat ( no pun intended ) as you, they do the mod, and turn on the parking lamps, and most might not notice the 1st few min, the headlamps are on. Others the fuse could blow very quick, and it is a flash of light.