Bronco Forum - Full Size Ford Bronco Forum banner

1 - 9 of 9 Posts

·
Registered
Joined
·
82 Posts
Discussion Starter #1
1978 Bronco. All exterior lights work; headlights, taillights, turn signals, high beams, etc. No issues outside. Inside, the dome light works, the high beam indicator works, and as I start the Bronco the red "brake" light momentarily flashes. Other than that, no interior lights work. All of the gauges work with maybe the exception of the voltmeter.

I have searched the site, none of the wiring schematics make sense with the lights that do work, and I don't know if 78 is different than 79. I was thinking that it was maybe the printed circuit board, but if that was out I should have the wiper and headlight lights? Maybe the gear indicator on the steering column? Maybe the turn signal indicators? Do ALL of the interior lights run through the headlight rheostat? It is odd to me that all of the interior lights are gone (other than dome, high beam, and a brake light flash at start).
 

·
Registered
Joined
·
577 Posts
in those years they also have bulbs one the back side of the instrument cluster with the printed circuit. mine was chewed all to pieces from people trying to replace the bulbs. I would look there. I had problems that you mentioned but it was about all due to the board. also just to make sure you turn the light knob all the way to the left just to make sure.
 

·
Super Moderator
Joined
·
26,007 Posts

·
Registered
Joined
·
379 Posts
had the same thing on my 94 and it was the headlight switch. on mine I could wiggle the knob and they would come on. changed the switch out and no more problems.
 

·
Registered
Joined
·
82 Posts
Discussion Starter #6
miesk5, I'm glad this is a "no flame zone". You are absolutely right. I looked at the link you sent earlier but did not spend enough time with it. My apologies and thanks.

I went ahead and ordered a new printed circuit board and headlight switch.
 

·
Registered
Joined
·
82 Posts
Discussion Starter #7
Update. Well, I dug into it today. I could not get a 3a fuse to not blow and have continuity between both sides of the fuse blades. Weird, but I'm not sure how sensitive the voltmeter is and if I should expect this. So I started to go through the wires in the harness and i have continuity with ground on just about everything! The harness itself looks pretty decent, not really cut up, everything in decent shape. I did find a blu/red wire hooked up to the ground in the aftermarket radio that the PO put in (that didn't work). To me this was the smoking gun, but I am still picking up continuity with all fuse blades on the instrument cluster, emergency lights, and one other there at the bottom of the fuse box. Weird. But, in the end I did get the turn signal lights to work, it was (hopefully) too bright to see the instrument cluster lights but I will check them when darkness falls.

I replaced the headlight switch, but I don't think that is an issue as the old one looked damn near brand new.

The continuity thing bothers me the most, why should I be picking up a signal between ground and the fuse blades?
 

·
Registered
Joined
·
82 Posts
Discussion Starter #8
update

OK, it's dark now. So I now have the headlight / wiper light working as well as the HVAC control light. But still no instrument lights. The printed circuit board looked pristine, but maybe it's time for a new one. I will get the voltmeter out tomorrow and see what I can see.
 

·
Registered
Joined
·
82 Posts
Discussion Starter #9
just a couple of pics







new headlight switch, new printed circuit board, and 2 distinct removals of horrible wiring by the PO. Hallelujah
 
1 - 9 of 9 Posts
Top