Bronco electrical problems

Tiny
RJOHNSN
  • MEMBER
  • 1989 FORD BRONCO
  • V8
  • 4WD
  • AUTOMATIC
  • 199,000 MILES
I have a 1989 Ford Bronco xlt 5.8L that I got from an auction. The car seems to have electrical problems because the back window doesnt go up, the drivers window goes up slowly, and the headlights dont work at all. I was wondering if we could tackle the headlights first. Is there any wiring diagrams or step by step as I am a novice. Thanks guys
Thursday, November 25th, 2010 AT 4:15 PM

3 Replies

Tiny
CARADIODOC
  • MECHANIC
  • 33,922 POSTS
A good place to start is at the head light switch and dimmer switch. Look for overheated terminals that are melted in the connectors. If nothing is found there, start at the head light switch with a test light or digital voltmeter. Look for one wire that has 12 volts all the time, then look for one wire that has 12 volts only when the switch is turned all the way to the head light position, not just the tail lights. That's a different circuit. If you have 12 volts coming in but you don't find a wire with voltage in the head light setting, replace the switch. If you do have that second wire with 12 for the head lights, look for the same color wire going into the dimmer switch and be sure the 12 volts is there too. There you should find 12 volts on one wire for low beams or a different wire for high beams. If that is part of the multi-function switch with the wiper and washer switches built in, don't be confused by their power wire. That one will only have 12 volts when the ignition switch is turned on. Again, if 12 volts is coming in from the head light switch but nothing is coming out, replace the dimmer switch.

For the front window, if it goes down properly the motor and wiring are ok. If it's sluggish going up, try spraying a silicone spray into the two rubber channels the glass rides in. Chrysler has a nice Silicone Spray Lube that works well for this.

Caradiodoc
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Thursday, November 25th, 2010 AT 7:34 PM
Tiny
RJOHNSN
  • MEMBER
  • 22 POSTS
Thank you so much, also my back tailgate will not open at all and the glass is stuck in the down position. As it is raining out here this is another problem. How would I get it open? I have traced the long rods from the assembly at the middle of the tailgate(inside the tailgate), and tried pulling the arm lever it leads to manually. So I have no idea what to do?
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Thursday, November 25th, 2010 AT 8:34 PM
Tiny
CARADIODOC
  • MECHANIC
  • 33,922 POSTS
Sorry, I can't help with that. Sometimes latches appear to stick when there is no pressure pushing the door or gate open, so when you also have a linkage-related problem, the latch won't pop open when you work it by hand. I'm guessing you already tried tugging on it while working the latches. That opening pressure comes from the two rubber bumpers in the corners and from the squished up weatherstrip. As a point of interest, you might try pushing the gate in tighter while pulling the latch. If the striker pins are adjusted in too far, you will have to really slam the gate to close it and very often the excessive pressure on the latch will prevent it from opening.

If there is a lock button on the gate, there could be something lock-related broken on one of the latches. Also, on some vehicles the gate won't open unless the window is rolled down, so even though it is down, the mechanism that tells that to the latch could be not working. Unfortunately even factory service manuals don't address things like that. They will tell you how to replace a latch but not how it works. You would have better luck asking someone at a body shop, or better yet, a Ford body shop.

You might also consider removing a latch from a salvage yard vehicle and doing an autopsy on it to see how it works.

Caradiodoc
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Thursday, November 25th, 2010 AT 11:23 PM

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