I have a 2002 xlt f 150 and about a week ago it started happening when i turn the key on the headlights turn on? It dose have the auto mode but i never use it and the switch is always in the off mode. Sometimes they only stay on for a couple miles then shut off sometimes they stay on till i get to where i am going then stay on about 30 sec. after truck is turned off? The headlights/taillights and dashlights. Anyone have an answer its driving me nuts as it never did this before. Thanks!

 

maybe the switch is bad. Thats an expensive switch it its the one im thinking.

 

Make sure the head light switch is in the vertical off position.
Move it through all positions then to off.
The left 11 o'clock switch position is the only way short of a fault the system goes to automatic.
Good luck..

 

Well they are getting bad. I NEVER use the auto on that is what gets me. I plugged the scanner in no codes i disconnected the battery for 6 hours still headlights come on when key is turned on? I work 3rd shift so last night i left the switch in off position and when driving the lights would flash off then come back on and i can hear a relay clicking from behind the glove box? I don't know if i should buy new switch or is there a control box under dash some where? Where is the ground? Tried moving switch like Bluegrass suggested same thing. Driving home after work they all ways shut off some times 1 city block some times a mile or two.

 

The fault is electrical, not with the engine control system.
There will be no codes for an electrical system fault such as this.
Try some things to see what the result is.
First observe if the Auto Lamp comes on when the fault occurs.
If yes remove fuse #29. This would remove power from the Auto lamp module.
Check to see if manual control of the head lights still work and if the trouble clears.
This begins to narrow down the trouble area.
The simplified schematic for this system is found in the Haynes Manual, page 12-23.
Good luck.

 

Bluegrass, headlights turned on when i started truck (switch in off position) pulled out #29 fuse lights stay on for about 30 sec then shut off. If i put fuse back in lights come back on did this twice same thing each time and manual control of lights still worked.

 

Fuse 29 removes power to the AUTO LAMP module.
If removing this fuse returns manual control, the auto lamp function circuit is faulty.
Likely the module or the light sensor or even a false ground.
You narrowed down the fault to this function.
If no other functions are affected with the fuse out, it's decision time.
Good luck.

 

Sorry but i have never been good at electrical systems. So pulling the fuse the module will have enough power stored to last 30 sec before lights are cut off? If so that has to be it because i don,t have a light sensor. Why can't i find this module on any parts website?

 

I was assuming the system was auto on. Actually did not see a sensor in the circuit. My bad!
It must be a delay off system.
It has a capacitive discharge delay that holds a relay up until it discharges and drops the relay.
Removing the fuse does not discharge it instantly.
Good luck.