i have an 89 f250 and the running lights wont turn off when i turn off the head lights. the only way i can get them to turn off is to unhook the battery. i tried a new head light switch but that did not fix the problem what else to be wrong?

 

you need to chase the running light wires and find out what wire is shorted to power.

 

You replaced the headlight switch but did you happen to look its connector while you had the switch out?

Connector tends to get hot and melt/deform causing issues, a replacement pigtail is available.

For example only > 1987-1997 Ford F250 Headlight Switch Connector - Body Mechanical & Trim - Standard Motor Products 87-97 F250 Headlight Switch Connector - 5327-05227931 - PartsGeek

 

Ok -- when you say "running lights" are you referring to Daytime Running Lights (typically found on Canadian vehicles , same year)?

If so -- there is a module LH side of engine compartment (near the horns) that could be malfunctioning............

 

Had that happen to me. The parking lights wouldn't shut off. The plug had melted and fused a couple wires together.

 

The plug looks good and the lights that won't turn off is the orang one's

 

Could be something has messed up in the trailer plug. Some of them have a live power wire in them for dome lights, etc.

 

did you ever find the issue? I have an 89 f150 with the same problem.

 

My guess is he realized the wiring looked sketchy and went back and probably replaced the headlight switch plug or found a short at the round connector going through the firewall......

He could of tried to put a seperate toggle switch too...........

The only way the running lights operate is through the headlight switch also through a factory security system going defunct and the relay that triggers the lights is stuck..........

As you can see although the dash lights come on when you pull the running lights the dash lights arent on and thats because theyre on a different circuit on the headlight switch which is the instrumentation and dash light dimmer function circuit..

Ive seen trailer plugs cause this too through trolley brake systems or 12v pins designed to charge trailer breakaway box batteries touching the running light pin inside the receiver plug w/male pins..................

Good Luck getting it ironed out...