Tailgate diagnosis- pictures to help

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memsiej
Posts: 174
Joined: Thu Mar 08, 2018 6:08 pm

Tailgate diagnosis- pictures to help

Post by memsiej » Mon May 03, 2021 7:23 pm

Trying to tackle this tailgate. It's never budged, either by switch or key. Got in and poked around, seems like there's been some custom wiring done. Fine- I just want to jump the motor and see if it's a dead motor or not. I figure if I put the correct motor wires onto a battery and it moves, I know I'm dealing with a bad switch, corroded wire somewhere, or a bad safety switch.

Which two am I jumping? Tan/brown? Or brown/yellow?

https://ibb.co/Br4yXLw
https://ibb.co/vd29Gvg
https://ibb.co/DL80XDM
1984 Grand Wagoneer V8 5.9


sirrus
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Re: Tailgate diagnosis- pictures to help

Post by sirrus » Mon May 03, 2021 7:55 pm

12v and ground on tan and brown, or vice versa - I don’t remember which way is up or down. Safety switch interrupts one on them if tailgate is open, it easy to test - two screws and you can pull safety switch out and test it with multimeter
Sometimes we reinvent the wheel not to have more wheels but to have more inventors

1988 Grand Wagoneer - AMC 360 with ProFlo4 MPFI, TF727, NP229 and lots of relays and other electric upgrades :)
Headlight harnesses and 3D printed parts for sale
How to clean electric switches (power windows, locks, seats)


Topic author
memsiej
Posts: 174
Joined: Thu Mar 08, 2018 6:08 pm

Re: Tailgate diagnosis- pictures to help

Post by memsiej » Tue May 04, 2021 8:39 am

Cut the brown and tan, connect 12v/ground to the cut ends pre-harness? Or disconnect harness from safety switch and connect to the harness?
1984 Grand Wagoneer V8 5.9


sirrus
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Re: Tailgate diagnosis- pictures to help

Post by sirrus » Tue May 04, 2021 9:02 am

I'd advise against cutting anything unless you absolutely have to. Use alligator clips and connect to existing connectors on the harness
Sometimes we reinvent the wheel not to have more wheels but to have more inventors

1988 Grand Wagoneer - AMC 360 with ProFlo4 MPFI, TF727, NP229 and lots of relays and other electric upgrades :)
Headlight harnesses and 3D printed parts for sale
How to clean electric switches (power windows, locks, seats)


Topic author
memsiej
Posts: 174
Joined: Thu Mar 08, 2018 6:08 pm

Re: Tailgate diagnosis- pictures to help

Post by memsiej » Tue May 04, 2021 9:10 am

Will try this evening and report back!
1984 Grand Wagoneer V8 5.9


SJTD
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Location: Lompoc, Sunland or somewhere between

Re: Tailgate diagnosis- pictures to help

Post by SJTD » Tue May 04, 2021 1:02 pm

Or, rather than cutting anything:

There's a connector under the body at the back where the wires come through the body from the tailgate. Demate it and put the power to the tan and brown there as Sirrus described. If it the motor works the dash switch or wiring is bad.

To double check the dash switch while you're there look for continuity to ground. Both brn and tan should show it if the front switch is good. If not, chase the wiring and the blk ground wire at the switch.

Then ground the neg lead of the meter connect the other to the tan. Should get 12V when the switch is moved to up. Connect the meter to the brn and should get 12V in the down position. With the key on, of course.

The above will implicate or exonerate the dash switch and its wiring.

If the dash switch works, remate the above connector, bypass the safety switch, unplug the motor and look for 12V between the brn and tan when the dash and rear switches are actuated.

Should get 12V in one direction and -12V in the other. Yes implicates the safety switch. No means it's the tailgate switch. This after putting the willy to the motor itself like Sirrus suggested.

So, what started a post pointing out the connector under the body evolved into this, a systematic way to check the system. Others might do it other ways but this should check everything.
Sic friatur crustulum

'84 GW with Nissan SD33T, early Chev NV4500, 300, narrowed Ford reverse 44, narrowed Ford 60, SOA/reversed shackle in fornt, lowered mount/flipped shackle in rear.


Topic author
memsiej
Posts: 174
Joined: Thu Mar 08, 2018 6:08 pm

Re: Tailgate diagnosis- pictures to help

Post by memsiej » Tue May 04, 2021 6:01 pm

Well, some good news some bad news. Picture says it all :D

https://ibb.co/6nD6xLk

How I closed the safety switch circuit
https://ibb.co/R9vrnQK

So, it makes me think it's the door switch but then why is the key in the tailgate also not working?
1984 Grand Wagoneer V8 5.9


SJTD
Posts: 1504
Joined: Tue May 21, 2013 12:02 pm
Location: Lompoc, Sunland or somewhere between

Re: Tailgate diagnosis- pictures to help

Post by SJTD » Tue May 04, 2021 9:19 pm

I take it you don't have a meter? You should. Maybe ten bones at HF.

Hard to troubleshoot without one.

The circuit is grounded through the dash switch even when using the key so a bad ground in the dash would cause both switches to not work. Same with bad wiring between the two. There's a separate breaker for the front and rear switches so they would both have to be missing or bad. One supplies the orange to rear switch.

There's the connector I mentioned above, another behind the dash
Sic friatur crustulum

'84 GW with Nissan SD33T, early Chev NV4500, 300, narrowed Ford reverse 44, narrowed Ford 60, SOA/reversed shackle in fornt, lowered mount/flipped shackle in rear.


Topic author
memsiej
Posts: 174
Joined: Thu Mar 08, 2018 6:08 pm

Re: Tailgate diagnosis- pictures to help

Post by memsiej » Wed May 05, 2021 5:42 am

I do have a meter, and am learning how to use it. Can you tell that electrical is NOT my strong suit?

When you talk about the "connector under the body at the back where the wires come through the body from the tailgate" are you referring to the one that connects brown/tan to yellow/brown going to the window motor? Or is there yet another connector I'm missing? Also, I don't even see any brown/tan wires coming through the wire bundle under the regulator...

Pic to explain. Red is the connector you're referring to, right? If so, no power there. And blue is the bundle where I strangely don't see any brown/tan wires.
https://ibb.co/2YN6jCj

Tried bypassing the safety switch already and no luck there. I'm leaning towards dash switch, key switch, or a wiring problem along the way.
1984 Grand Wagoneer V8 5.9


SJTD
Posts: 1504
Joined: Tue May 21, 2013 12:02 pm
Location: Lompoc, Sunland or somewhere between

Re: Tailgate diagnosis- pictures to help

Post by SJTD » Wed May 05, 2021 8:43 am

Nope, under the body. Gotsta lie on the ground to find it. A three pin connector with the big brn and tan wires a small wht one between them.

Mine's an '84 too so everything should be the same.
Sic friatur crustulum

'84 GW with Nissan SD33T, early Chev NV4500, 300, narrowed Ford reverse 44, narrowed Ford 60, SOA/reversed shackle in fornt, lowered mount/flipped shackle in rear.


Topic author
memsiej
Posts: 174
Joined: Thu Mar 08, 2018 6:08 pm

Re: Tailgate diagnosis- pictures to help

Post by memsiej » Wed May 05, 2021 9:59 am

OK! Dash side of that under-body harness picks up about 10A when dash switch is actuated. No life from the motor side of the harness, so I THINK I've isolated the problem to the tailgate switch. In my perfect world, I'd love to just wire directly from dash switch to window motor. I don't need a tailgate switch.

Pic of Plan: https://ibb.co/cJVXmgq
Cut brown and tan where they enter from underneath, wire directly to motor. This *should* take the dash switch directly to the motor, bypass both the key switch and the safety switch.
1984 Grand Wagoneer V8 5.9


SJTD
Posts: 1504
Joined: Tue May 21, 2013 12:02 pm
Location: Lompoc, Sunland or somewhere between

Re: Tailgate diagnosis- pictures to help

Post by SJTD » Wed May 05, 2021 12:05 pm

I assume you mean 10V. Seems low. Make sure the polarity reverses when you move the switch the other way.

And that both tan and brn wires have continuity to ground with the dash in the center position.

If those check out your plan should work. Would be more elegant to make some jumpers so you can fix it later. I wired in some relays.
Sic friatur crustulum

'84 GW with Nissan SD33T, early Chev NV4500, 300, narrowed Ford reverse 44, narrowed Ford 60, SOA/reversed shackle in fornt, lowered mount/flipped shackle in rear.


Topic author
memsiej
Posts: 174
Joined: Thu Mar 08, 2018 6:08 pm

Re: Tailgate diagnosis- pictures to help

Post by memsiej » Wed May 05, 2021 3:03 pm

SUCCESS!

Pic of bypass https://ibb.co/3TqRys9

I did tuck things away more neatly and ziptie them into place. Someday when I fix the broken off lever and can actually drop the damn tailgate, maybe I'll look into replacing that key switch. But for now it works from the dash and that's that.
1984 Grand Wagoneer V8 5.9


Srdayflyer
Posts: 16
Joined: Mon Mar 18, 2019 2:08 pm

Re: Tailgate diagnosis- pictures to help

Post by Srdayflyer » Thu May 06, 2021 9:49 pm

i would recommend checking the condition of th wire harnass where it goes from the tailgate thru the lower body opening , i had to pull that harnass out and rewire it because after 38 years several wires were nearly broken in two from bending


Topic author
memsiej
Posts: 174
Joined: Thu Mar 08, 2018 6:08 pm

Re: Tailgate diagnosis- pictures to help

Post by memsiej » Fri May 07, 2021 4:42 pm

It looked surprisingly OK, thankfully. Grateful that that harness was pointed out to me- I wouldn;t have known about it otherwise.
1984 Grand Wagoneer V8 5.9

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