Headlight switch issue
 

So I have a 1990 F-150 straight six and it has the original headlight switch in it. It's the pull out knob that works headlights/dash/interior. Read a few posts on here but didnt really find anything useful to solve my issue. The only way to get the dash,headlights, and tail lights on is to pull the switch all the way out and jiggle it until they all come on, otherwise only the headlights come on, or only the dash/tail lights come on. No big deal right? Just put in a new switch. Got a new headlight switch and now only the headlights come on regardless of what position the knob is in. I've been through several different switches, from different companies, all for the right year and model, and all have the same problem. Now what I noticed, was on the original switch, which worked but was just loose and worn out, the bottom left terminal has a 13 stamped into it, and all the new ones, have a 22 stamped on that terminal. Theres no blown fuses anywhere, no burnt wires, and the connector/harness is in perfect working condition. Only thing I can think of is the difference between the 13-22 stamped under the terminal and have no idea why its different, even the motorcraft switch has a 22 stamped on it that I got straight from Ford. Anyone else have this problem or know a solution? Sorry for the long post.

What about a new pigtail?

Corroded, loose wires inside?

I'd trace all the wires down and make sure they are good front to back... I'm not sure what the ohm/amp reading should be but I'd put a multi-meter on all the wires to test them. One could be dead shorting to the chassis or metal some where. If all checks out you might want to check the junk yard for an OEM switch off an older 87-91 truck and see if that makes a difference...

The only person I know that could possibly know the answer to the 13-22 question is "NumberDummy" so you might want to search for him and send a PM to him personally. He is a parts expert on these trucks.

Tore it all apart this morning and checked/tested everything and it all checks out to spec. For now I just ran a toggle switch to the park/dash lights until i figure it out. Thanks for the replies, going to send that guy a message after I post this.