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Discussion Starter #1
Sorry for asking the question that everyone has asked - but I just can't find the answer anywhere.

I have a 1979 Bronco - the tailgate is almost rusted away & I found a brand new repop locally. The catch is it came from a 1996.

I am not worried about fitment - I can fabricate the correct bracket for the latches (already have 1 made). Getting the wiring correct is a concern though.

So - I've done a bit of research - BW wire is the "hot" the purple & blue & purple & green wires are the window wires & the 1996 harness has a 4th wire used for the rear defrost (which I do not need).


I have bench tested the motor itself - 2 wires - hot/ground goes up - swap over - goes down. All good.

However - I want to bench test it through the harness / switch. I want to test that the rear window switch works before I start trying to attach this to the truck (if it doesn't work I want to fix it while I have easy access).

How do I go about bench testing this tailgate wiring?

153565


Since these are the 4 wires that run everything - how do I jump test this?

I ran a jumper for the door latch switch (which is missing from the new tailgate).

I tried running a pos & ground wire to each post in all configurations. Lets call them pins 1, 2, 3 & 4. I put power to pin 1 then ground to pin 2, then pin 3 then pin 4. Nothing happened. So then I moved power to pin 2 & put the ground to pin 1 then 3 then 4. Nothing. Etc. all the way around.

the thing is - if this works - the truck is sending power & ground to one or more of these pins - I should be able to simulate that & test the switch at the tailgate. I should also be able to simulate what happens when the front switch is used.

I want to bench test this & make sure it all works before I try & install it. Once I know it works I'm going to take it all apart & paint it. Then put it back together & then install it on the bronco.

I've thought about just swapping in my existing wire harness - except the existing door key switch does not operate either up or down - so I'd just be moving the problem from one tailgate to the other.

Has anyone ever done this?

Oh- & once I figure it out - I'm doing to do a full picture write up of fitting a 1996 tailgate to a 1979 bronco. I have a ton of pictures.
 

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Discussion Starter #2

So I found this diagram / write up online. This helps explain how the darn thing works.

I think (will test tonight) that I need 2 hot wires & 1 ground.

Black/White wire is always hot. It is not connected to the ignition key.
Purple/Blue & Purple/Green are alternating ground wires.

So check my logic here - I "think" I can bench test this thing by connecting power like this.

Black/White to 12 volt source.
To send the window up - I need to jump the B/W wire over to P/LG & I need to ground the P/LB. 3 wire action - where my previous tests were 2 wire. (2 hot & 1 ground).

To send the window down - I need to jump the BW wire to P/LB & I need to ground P/LG.

This would be a bench test for the dash switch.

To test the key switch at the tailgate - Again Black/White gets 12 volts. But BOTH P/LB and P/LG wires need to be grounded. Again - this is a 3 wire test (2 grounds & 1 pos).


Does this sound right? I'm going to try it out tonight & see what I get.
 

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Discussion Starter #4
On paper it works - but in reality - it didn't do anything. HMMMMM
 

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Wiring is not my expertise by any stretch of the imagination, but isn’t there some sort of safety to make sure you can’t roll the window up when it’s open? Or am I just making that up? Maybe that’s why nothing’s happening in the current setup.
 

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Discussion Starter #6
So last night I tried again. No luck. But I read somewhere that instead of using a jumper on the safety switch use a light. That way you can see if juice is flowing.

So the led told the story. B/W to hot. Both others to negative & pushing the button on the switch. Should work. One side did nothing. The other side would just barely tingle the led. This switch is the unknown.

At least I know the harness currently on the bronco is good. I have to check the fuses.
 

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Discussion Starter #7
I think I'll do the solinoid modification when I install the new tailgate. I'm planning to use the wire harness & key switch from my existing truck. Can't seem to figure out the one on the new tailgate & other than my key switch not working - everything else works from the dash switch (up & down) so I know all the wires are good.
 
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