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Discussion Starter · #1 ·
Before anyone asks, yes I searched. There's a lot of .is leading info on my particular issue. Key switch for the tailgate window doesn't work. Dash switch works perfectly, it's actually brand new. I even bypassed the safety switch. I tried to probe the black/white wire but I'm either not probing far enough, or its not hot. Where should I look from here? I've eliminated what I read could be the problem "99% of the time". Thanks.
 

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ok first thing you need to do.

Crawl under the back bumper. Up in the corner below the drivers side tail light is a couple of white connectors.


Determine which one of these connectors is the one for the tailgate. Just check the wire colors. BK/W, PK/LB, PK/LG, and BLK Ground. The ground above is the tailgate ground so just trace which connector it goes to and then disconnect it. Using your digital multimeter, Set your meter to Volts DC in a range you can measure 10-14 volts. Probe your black lead on the ground and your red lead on the BLK/WT wire. You should read 11.5-12.5 volts there. anything lower and you have problems between the fuse panel and the connector. You want that voltage to be as close to battery voltage as possible. The lower it is suggests the wire jacket is cracked or in poor condition, in that case it should be changed, and I would up the wire size to one size bigger. If your voltage is fine, you can proceed further up the harness.

Remove the drivers side tail light assembly. Pull the wire harness coming from the tailgate back up thru the body until it comes out of the tail light passage. Clean and inspect the wires from the connector to where it goes into the tailgate. If you find nothing, you will need to dig further.

So lower the glass, drop the tailgate, open up the access panel, close the drivers side latch halves so they are int he closed position, this will allow the window to roll up with the tailgate down. No get some saw horses or some other suitable prop, roll up the window and support the glass.

Get your camera phone, point it down inside the tailgate toward the drivers side latch and photograph the safety switch.


Unplug the wiring connected to it.

Now you need to remove the key switch assembly. On top of the post where the key inserts is a snap ring. Remove it.


Here is a diagram how the key switch is put together.


Note that you ONLY have to remove the top snap ring and the parts you need will slide right off, no need to go any deeper and risk losing any of those small parts.


Unplug your window motor and defrost grid if you have that, and remove the complete harness from the tailgate.

Now with it on the bench, you can more closely examine the key switch and the rest of all the wiring. Strip away all tape, wiring loom and inspect each wire from the connector to each component. Replace any that are broken/cracked/or otherwise bad. Usually the contacts inside the key switch push buttons is corroded from all the moisture getting in the tailgate over time. You COULD try to pry them apart and clean them up, but you will most likely not be able to save them. So now what?

Well now you need some parts. They do not sell these parts any more so you will have to be creative. So Go to ebay, and search for a Tailgate window wiring harness for a ford station wagon.

What your looking for is something like this.


Look familiar? Its the same switch. You can drill out the rivets holding the switches in your key switch in the bronco, cut the wires and do the same to the ones from the donor harness, then splice in the wire, solder it, shrink wrap it, then rivet the switches back in place, connect it all up and it should now work again.
 

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With the exception of one dash switch, every tailgate issue I've ever had is because of broken wires in the harness where it flexes when you open the gate.
 

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Green Sales Company is showing 73 of part number C9AZ14529E
Main
This is the part number that I found for a 1969 Ford & Mercury Wagon Rear Window Switch assembly.
 

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With the exception of one dash switch, every tailgate issue I've ever had is because of broken wires in the harness where it flexes when you open the gate.
This was exactly my problem.

After futzing with all kinds of different fixes that seemed to work for a short time, I opened the harness between the truck and tailgate.

There was the source of my migraines.

Repaired the harness and no issues now for years.

Works great from the key or dash switch.
 

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Discussion Starter · #8 ·
Okay. I Unplugged the tailgate harness that's behind the gas tank, probed all 4 points on the connector and I got zero readings, especially the blk/wht wire on the truck side of the harness, which I believe is supposed to be constant 12v? I dont have a way to test continuity through the tailgate side of the harness to see if I get a reading back. I checked all the fuses again and they're all good, I even switched the two huge silver fuses that are for the power windows/tailgate window, and the power windows still work and the tailgate window does not. Where do I go from here? It stopped all together one day from the key switch, not a work sometimes/not other times. Just stopped. Idk.
 

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Looking at the diagram,




you will see the blk/wht wire is powered by a Big Giant Silver Circuit Breaker. You can try replacing them both. That would be the first thing to try. but if you switched them and nothing changed, move on to the next step.

Available from Rockauto.com
STANDARD MOTOR PRODUCTS BR220 {#D9AZ14526B} 20 amp circuit breaker


From there, I would do a visual inspection of the fuse panel. Look for anything melted. Its not going to be easy to see, (its much easier with the dash pulled) but you can unbolt it, and wiggle it around, and use a mirror to look at the back side of it. Your interested in looking at the circuit where the big silver circuit breakers reside.


From there, you will need to trace down the path of the blk/wht wire. Im not 100% sure where it runs, likely down the rocker panel, then out thru the bundle that goes to the transfer case, but dont quote me on that. Its very easy to sink a screw thru a wire when your screwing down the floor trim by the doors. Thats usually where it happens. But you need to check it all.
you can trace it from the back forward or from the fuse box backwards. Its not going to be easy either way. But if your determined to make it work, you will likely have to replace that wire anyway.

I would double check with a multi meter that you dont have power to the blk/wht wire at the tailgate connector. Maybe remove the ground, clean up the metal with a sanding disc, then screw it back down and try again. once you double checked that, paint the ground lug area you scrapped clean to prevent rust.
 

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I too had this problem for my 92 and the dash switch seemed to work fine. The rear key switch( for years) was a hit and miss .Finally the key switch quit working 2 summers ago .(DASH ONLY WORKED).Doing searches I came upon The Bronco Tailgate Mods. It mentioned the stock high resistant wiring . After completing the improved circuit mod and with the same stock switches, both work great. I like the idea of not having to turn the ignition on to use my dash switch. My B/K W wire DID have power back to the rear key switch. Noticed I mentioned HIGH RESISTANCE ,the new improved mod lowers that. Good luck! TR
 

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Correct, and thanks , I also though my rear window switch was bad until I rewired it, adding new relays. Super motors also has a page with 6 diagrams , stock ,improved ,hot switched, loaded circuit, one touch and simplified .It applies for 87-96 and 78-96. TR
 

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Discussion Starter · #13 ·
How much would it cost to get one of you guys to come rewire my tailgate? Haha. I'm terrible with electronics and how they work. In going to check my door sill area because I have taken that skuff plate off a bunch of times.
 

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You were on the right track about checking your power at the tailgate. Keep at it, the bk/wht wire is your feed. My tailgate had been a Pita for years . You can also remove your drivers side rear tail light .Check all your wiring before assuming .Good luck TR
 

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Discussion Starter · #15 ·
I had already pulled the drivers side taillight and checked for cracks in the wires there, removed and cleaned the ground thoroughly (not sure if it's for the same harness), and checked for cracked wiring between the tailgate and the body. The loom is severely dry and cracked in half in a few spots, but the wires/insulation looked good. But if I'm not getting power at the connector behind the tank then it shouldn't matter. I have to pull the door sill and check that stuff and the fuse panel. I hope it's something simple.
 

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Found my issue, the plug behind the brake light was shot, dry rotted. Fell apart as i attempted to separate it. Ran a test with crimps. Good to go! Good luck on your gate. Ill be rewiring mine tomorrow
 

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Sorry to switch subjects here but I have the reverse issue. So I had no tailgate switch as they're hard to come by but found one at a junk yard a few days ago. After repairing broken wires in the harness and installing it. The rear tailgate switch works but the dash switch doesn't. I had the two relays wired in before which worked fine, I just wanted to have the ability to use both.
I'm stumped though, the dash switch is good and the wiring to the rear as the dual relay way worked before but looking at the wiring diagram there really isn't any way for the tailgate switch to work and not the dash switch as it gets its ground by going back through the switch so I'm extremely confused. The rear window moves slow anyways so I'm going to end up putting the relays back in but with the tailgate switch in too. But I'm still not sure why it isn't working. Electrically, according to the diagram that's not possible unless I had no power to the dash switch which I do.
 

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I rewired and replaced my old wiring using this diagram and 10ga wire. I used heating hose to cover tjhe wire at the tailgate flex and hrd wired around the taillight connectors using solder and epoxy. I also installed a SPDT switch near the cargo light. Now I can move the winmdow any time I'm using the back for camping-out and I no longer need the ignition key for the dash or the cargo switches! Word of advice though... Replace the nylon window govenor gear, as it is older that dirt and will fail on a rainy day if you don't!

http://www.fullsizebronco.com/forum...361210-tailgate-rewire-works-100x-better.html
 

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Does any one know of a way to just run direct power from the dash switch to the tailgate motor. The tailgate switch was taken apart by the p/o and can't find another. Dash switch shows power but it isn't getting to tailgate. Motor is fine, as we have a spare battery sitting in the back and can jumper it to lower and raise the glass. Can the tailgate switch be completely removed from the equation? Don't have a key for it anyway, just want to be able to lower and raise glass from the dash.
 
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