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Tailgate window relay

Posted: Tue Jun 19, 2018 7:18 pm
by TeaBag
Does anyone know where the tailgate window relay is located on the 1991 GW?

Re: Tailgate window relay

Posted: Tue Jun 19, 2018 9:01 pm
by SJTD
On owner's wish list?

Re: Tailgate window relay

Posted: Tue Jun 19, 2018 10:51 pm
by dodgerammit
You have to build one. You actually need two relays. One for up, one for down. And, to make it work correctly, ditch the factory style switchback system (One switch puts current through the other using differing poles for positive and ground).

This may help you:

http://www.fsjnetwork.com/forum/viewtop ... 95#p151695

Re: Tailgate window relay

Posted: Wed Jun 20, 2018 4:08 am
by TeaBag
Hum...the wiring diagram I have from the Chrysler service manual shows one.

Re: Tailgate window relay

Posted: Wed Jun 20, 2018 6:04 am
by acct21
There was not one in '90. Can you post a pic of your schematic?

Re: Tailgate window relay

Posted: Wed Jun 20, 2018 6:40 am
by dodgerammit
acct21 wrote:There was not one in '90. Can you post a pic of your schematic?
This is from Tom Collins' site. 1990. No relay. I see no reason Chrysler would have changed it for one year knowing the GW was dying that next year.

http://oljeep.com/gw/elec/90_numeric/90 ... age-41.jpg

Re: Tailgate window relay

Posted: Wed Jun 20, 2018 5:39 pm
by TeaBag
IMG_5505.jpg
IMG_5504.JPG
This is from the Chrysler service manual for the 1991. Both diagrams came from this manual and both show the relay.

Re: Tailgate window relay

Posted: Wed Jun 20, 2018 9:15 pm
by SJTD
You is right.

What a klooge. Leave it to Jeep to spend the money to add a relay but keep that stoooopid wiring scheme and the fancy custom switches instead of a couple of simple SPDT center off's. But I suppose it they knew it was for only a year or two it wouldn't be worth it to do new switches.

Based on how it's wired I'd assume it's in the tailgate.

But what the heck. Why not put it in the dash so you could run the signal wires back up front again then the power wire back to the tailgate?

Re: Tailgate window relay

Posted: Thu Jun 21, 2018 4:19 am
by fulsizjeep
This is the funniest thread I have read in a while and of course I have no answers...

Re: Tailgate window relay

Posted: Tue Jun 26, 2018 7:31 pm
by TeaBag
OK, this one is really puzzling me. My 1991 shows all the indications that it is wired like a 1990. It must be an early 91. But later model diagram shows a relay,however, I can’t seem to find the relay anywhere. The switch connections all mirror that of the 1990 wiring diagram.

My real problem is the switch on the dash stopped raising and lowering the window one day out of the blue as if it was completely dead. When I checked for power at the switch the switch has power and ground. The window at the time would still go up and down with the key switch in the tailgate door. Now the window will only go down and will not come up with the key switch. the dash switch still is not working n either direction. I have power going to the keyswitch and I have power going to the dash switch.

I can hotwire power directly to the motor and it will go up and down. I have jumped the tailgate safety switch and that is not a factor. Currently the only way it will work is going down with the key switch . I used an ohm meter to check out the function of the tailgate key switch and it seems that the switch is allowing current to pass in both directions as you would expect.

The only thing I can think of is a bad ground wire somewhere? But I can’t seem to find exactly where it grounds. The switch on the dash has two 10 gauge ground wires going to it. And they check OK. In the tailgate there is no real ground wires as both switches are designed to reverse the polarity to get the motor to change direction.

What am I missing? I know there is a ground wire inside the tailgate but that appears to be only for the License plate light?

Any thoughts?

Re: Tailgate window relay

Posted: Tue Jun 26, 2018 8:09 pm
by Curly
Check for broken wires where the wires enter the tailgate. The ones on my Cherokee were broken from flexing over the years. The problem was visible once I removed the tape wrap on the wires.

Re: Tailgate window relay

Posted: Tue Jun 26, 2018 9:57 pm
by dodgerammit
The grounds are through the switches. They are wired similarly to the door window switches. Reverse polarity design. I agree with Curly. Check the hinge area for broken wiring.

Re: Tailgate window relay

Posted: Wed Jun 27, 2018 4:40 am
by TeaBag
Thanks for the advice. I'll check those wires.

Just thinking about it, It seems to me that the wires passing through the tailgate hinge area would not have any effect on the function of the keyed switching the door as long as the power wire is intact? In which case-mine is. It looks like the other wiring (from the keyed switch to the safety switch and motor) are all within the tailgate and don't pass over to the frame?

Am I thinking that through correctly?

Re: Tailgate window relay

Posted: Wed Jun 27, 2018 6:29 am
by will e
SJTD wrote:On owner's wish list?
:funnypost:

Re: Tailgate window relay

Posted: Wed Jun 27, 2018 7:59 am
by SJTD
If it's the same as earlier nonrelay two wire motor wiring, the ground path is still through the dash switch when the key switch is operated.


In their center positions, the key switch passes both motor leads straight through to the dash switch which grounds them both.

When the key switch is moved one lead disconnects from the dash switch and connects to 12v while the other lead continues to pass the ground through to the dash switch.

When the dash switch is moved it disconnects one side from ground and connects it to 12v while the other remains grounded.

Re: Tailgate window relay

Posted: Thu Jun 28, 2018 5:01 am
by TeaBag
Ok. That makes sense. I’m starting to suspect an issue with One or both of the switches. I did continuity checks on all the wiring from front to back and everything checked out OK. A little bit of resistance between the ground wires from the front switch to the frame but nothing too bad. I can make the Motor go up and down if I wire it directly to the battery . I can also just make it go down ( only in one direction ) with the key switch only.

Re: Tailgate window relay

Posted: Thu Jun 28, 2018 7:10 pm
by TeaBag
All right, Its fixed! Turns out the keyed switch was bad. Once I removed the switch from the housing, it fell apart in my hands. Fortunately, I only live 20 min from Team Grand Wagoneer, so I was able to get a replacement switch quickly and get it fixed.

Special thanks to SJTD for correctly explaining how the circuit grounds. This led me back to the tailgate switch and to finding the problem.

Re: Tailgate window relay

Posted: Thu Jun 28, 2018 10:32 pm
by dodgerammit
TeaBag wrote:All right, Its fixed! Turns out the keyed switch was bad. Once I removed the switch from the housing, it fell apart in my hands. Fortunately, I only live 20 min from Team Grand Wagoneer, so I was able to get a replacement switch quickly and get it fixed.

Special thanks to SJTD for correctly explaining how the circuit grounds. This led me back to the tailgate switch and to finding the problem.
Good to hear!