What about the illumination of the switches for doors, windows and mirrors in the two front door panels?


George

 

None of the are lighting up.
The window mirrors were always out.

 

A common problem is the thumb wheel in the headlamp switch assembly but that does not appear to be the case here or at least not entirely the problem because you have illumination lights that go through that wheel that are out as well as bulbs that do not go through that wheel that are out. They all get power from the headlamp switch however. It would be easy enough to say that the HL switch is the problem but you said that there is no power from the PARK LP fuse in the UHFB so that would suggest a power source problem to the hl switch but you have park lamps and those should also be dead.

Do you have access to the back of the headlamp switch at the connector? If so measure voltage at both orange wires with the connector unplugged


George

 

In one of my replies I explained that I had mistakenly tested the wrong fuse. I'm getting power from the PARK LP fuse UHFB 11.90 12.58 volts.

 

OK then 2 more tests and we are getting close. With the headlamp switch in manual park light position verify that parking lights are on and then test Park LP fuse 5 and Illum fuse 12 in the IPFB to the left of the dash

George

 

I'm getting like [12.1 on the 5] and [0 on the 12].

 

You appear to have more than one thing wrong regarding your IPC lights, dash lights and switch lights (ex: door switches for locks and windows). Here is the circuit section:



You verified 12v at the Park LP fuse in the UHFB (point 1) which makes sense since you have parking lights. This means that the headlamp switch has power for park (not shown in this diagram) and illumination bulbs. There are two outputs from the headlamp switch for illumination bulbs, the dimmer output (point 2) and the non dimmer output (point 3). You have no output at point 2 (IPC, dash lights, etc) so the dimmer function is broken and the headlamp switch needs to be replaced. You do have power out on the non dimmer circuit at point 3 for things like the door switch illumination bulbs but those bulbs don't work. Either every bulb is burned out or there is another circuit problem. After you get the HL switch replaced and hopefully get your Instr Panel lights back then we can work on the non dimming leg through point 3.

Also, let me know if you need anything on your starter circuit if the truck fails to start again.


George

 

Tomorrow I'll go looking around for a hl switch at a junk yard or if I find one online for a decent price I'll look into that.
Also I really appreciate the help.


What's the symbol with the circle and curvy arrow in the headlamp, to the left of the 2-wire?

 

If you mean #4 in my new drawing that's the internal illumination lamp in the headlamp switch assembly.




George

 

Oh, I see. I just took the switch apart and it looked like a bullet.
I figured it was a light or something.