Grand Wagoneer Tailgate Window Key Switch Conversion

[JeepofTheseus]

I'm hoping someone has run into this before. I searched the forums and found a few threads addressing failed tailgate key switches, but didn't see an exact match for my situation. I have an 88 Grand Wagoneer. The dash switch for the tailgate window functions very well (someone previously bypassed the safety switch so I suspect that wasn't always the case). The tailgate key switch has never functioned since I've owned it, so I purchased the conversion kit from BJ's. When I got the tailgate apart I discovered the original toggle switch was in bad shape. I replaced it with the new conversion kit and I cannot for the life of me get it to work. I followed the instructions exactly. Verified all the wires connected to the correct positions several times and tried swapping the tan and brown up and down wires as the instructions suggested. Every variation continued working from the dash switch, even if up and down were swapped in the various configurations, but the new toggle switch did nothing. I even found a second conversion kit the previous owner left at the bottom of the box of parts he threw in with the truck. I tried that switch thinking maybe there was a problem with the unit itself. Same process and same result. I'm new to this and am trying to learn as I go, but I feel like I'm at a dead end with this. I suppose I could be happy that the dash switch works, put the tailgate back together, and get on with my life, but I'd really like to get everything working on this thing if I can. Any thoughts or insight would be greatly appreciated.

[sierrablue]

Have you checked for voltage anywhere? It sounds like you've tested everything else...

Also check all the relays and grounds making sure they work properly, and check for blown fuses...

Have you bench tested the wiring harness/switch? See if that system works right if you hook it to a battery on the bench..?

[Srdayflyer]

have you checked the tailgate wiring harnass its only 5 wires and a seperate 2 wirs for the defrost system, the wire harnass passes thru the body at the lower driver side rear thru and opening in the tailgate, it is there where i foung several wires broken inside the protective sheathing, i replaced the wire in that area approximately 18 inches, i removed the rear window while i worked on this troubleshooting. also check the window safety switch , again this switch looks like a hook arm this is in the tailgate driver side (2) wires, my original switch but replaced it with 1 from BJ'S which is an aircraft grade switch water proof and very heavy duty, reach out to me if you want additional help, ive rebuilt the complete tailgate so i have a vg knowledge of the tailgate area

[JeepofTheseus]

Thanks for the quick responses. The tailgate safety switch was taken out of the system before I bought it. Brown wire taken off connector to hooked safety switch and spliced together. Maybe a previous attempt to solve the same problem I'm dealing with now? I can raise and lower the tailgate window from the dash even with the tailgate down. Electrical stuff is my area of lowest confidence and zero experience, so these may be dumb questions. I'll examine the harness for breaks and test wiring, but as part of the learning process, I'm trying to figure out how it all works. So I've got three wires from the tailgate harness that connect to the conversion toggle switch: Orange, which I assume is power. A brown and a tan both with stripes that control up and down. From the toggle switch to the tailgate window motor itself there are the solid brown and tan. I have one defrost wire that connects to the window but the other is frayed and broken. The window was out and disconnected from the one defroster while I worked on the key switch. So here is my dumb question. If the power necessary to operate the tailgate lift motor via the dash switch runs through the wired up replacement switch, where would be a good place to look for a failure? Even if there's an issue with constant power, shouldn't the switch function under accessory power? Is there another ground other than the one at the bottom of the tailgate where the harness comes in? I suppose a good place to start would be giving that a good once over, checking for breaks, and start testing stuff. I really appreciate y'all's help. I was completely at a dead end so thanks for giving me a couple directions to go.

[JeepofTheseus]

Update if anyone is interested. I took y'alls advice and checked for bad wires then got out the multimeter to test the voltage. 12 volt constant to the switch. When the key switch is in the neutral position, no voltage goes from the switch to the motor. When I engage the switch in either direction, I get 12 volts all the way to the motor. Like I said in my earlier post, I'm new to this, but that seems like the way the switch should be functioning, doesn't it? I certainly could be missing something, but I don't have the slightest idea why it doesn't power the motor under 12 volt constant. When I go to accessory power it works like a champ. While I had it all apart, I took the opportunity to swap out a new window lifter bar and new clips to the regulator arms and put in some new weather stripping and window wipes that the previous owner gave with the truck. For the time being I'm closing the tailgate back up and will be happy that it works so well from the dash switch. Thanks again for helping out. Very cool of y'all to share your knowledge with a newbie. If I ever know anything worth sharing I'll try to do the same.

[Srdayflyer]

you should have 12 volt power all the time at the tailgate switch . do you have the manual look on line at oljeep.com there are several year manuals

[sierrablue]

Is there like a second relay or something in there for the switch in the tailgate, or something stupid like that, and the relay is bad and/or not making a connection? I wouldn't put it past AMC...

How are the spots where the motor mounts? Much rust there? Are all of the grounds in the tailgate CLEAN, not just grounded?

Complex wiring like this is one time I do like having the service manual, and I can scan the diagram and print it out, and then use colored pencils to highlight the wires I need to focus on. Even on mine with the EZ Wiring harness/fuse block installed, I've done that quite a bit. And I have no power anything on mine...electrical power anyway.

If it was mine I'd also go in with some electrical parts cleaner (and gloves) and clean all the connections. Then before putting it together I'd put a dab of dielectric grease on each individual prong--be careful that you don't end up with the grease from different prongs touching though.

Then if it still wasn't working I'd start double checking all my fuses and relays, and be looking at the diagrams to figure out where each wire goes.

[JeepofTheseus]

you should have 12 volt power all the time at the tailgate switch . do you have the manual look on line at oljeep.com there are several year manuals

I've got 12 volt constant to the tailgate key switch and 12 volt to the motor from the switch when I engage the switch in either direction. It just doesn't work. Works great from the dash switch under accessory power. Can't figure out why the motor won't engage if the tailgate key switch seems to be sending power as intended. This is the bj's conversion if that makes a difference. Thanks.

[JeepofTheseus]

I've got the hayne's manual and the wiring looks like the diagram and like Srdayflyer described it in the earlier reply. The black window defroster wire was frayed and broken. The orange is still intact with the connection to the other side of the window. The safety switch was taken out of the system (brown wires spliced together). Otherwise I don't see anything out of the ordinary. Good call on the dielectric grease and cleaning the grounds etc. Maybe I'll get new hardware to secure the ground just to rule it out. At this point all I can think of is an issue with the motor itself but I don't have a clue what that could be.

How do you like the EZ harness? I keep looking at the 21 circuit option on BJ's but it seems pretty daunting to take on at my experience level.

[Srdayflyer]

i removed the window motor and used jumperwires and a 12 volt converter i have to check out i had the wires coming from the bj's upgrade switch to the motor to make sure i had it wired correctly, easier to work on it on my work bench , one i got it working i installed all of back in the tail gate, it works like factory

[sierrablue]

I've got the hayne's manual and the wiring looks like the diagram and like Srdayflyer described it in the earlier reply. The black window defroster wire was frayed and broken. The orange is still intact with the connection to the other side of the window. The safety switch was taken out of the system (brown wires spliced together). Otherwise I don't see anything out of the ordinary. Good call on the dielectric grease and cleaning the grounds etc. Maybe I'll get new hardware to secure the ground just to rule it out. At this point all I can think of is an issue with the motor itself but I don't have a clue what that could be.

How do you like the EZ harness? I keep looking at the 21 circuit option on BJ's but it seems pretty daunting to take on at my experience level.

I don't think it's the motor, unless it somehow has 2 input wires. Since the switch on the dash works how it should Idk how it could be...

The EZ harness is pretty good. Initially I wouldn't have picked it, and was disappointed that it had it when I got it. However, having had some electrical issues and such since, it has been very convenient. The wires are all labelled with what they go to, and it includes a lot of stuff mine didn't originally have, including power locks/windows, a modern 3-fuse radio system, electric fan, electric fuel pump, electric choke, cruise, A/C...I'm not using all of them but they're good to have. It also uses modern fuses so there's no question if you're getting the right ones. It's not as good as it could be if you were to go through and 3D print a custom block with EXACTLY what you need for yours, but it covers the bases really well.

It's not as bad as it seems, especially if you're just going through and wiring the whole thing. Personally I like to take some time and figure out each individual system, and check it all, and follow the wires and such. Just take it one wire at a time; it's slow, but then you'll know you did it right. IMO the worst is with a factory harness that has been modified some, and you're only trying to make one thing work but have no idea how it's been modified.

[JeepofTheseus]

Ryan at BJ's put me in touch with their electrical guru. Heck of a nice guy and he's offered to help me figure it out. Rain and no garage has the project sidelined for the time being, but I'm going to get back in there and take some pics and vids and send them over to him to help diagnose it once I get a nice day.

[67GMC]

Never underestimate a good ground LOL!. I keep a long length (10') of wire with alligator clips on both ends to use as a temporary ground when this kind of stuff it happening. I would clean off all the contacts to the motor, the motor ground to the tailgate and anywhere else. You can use the long ground wire to go from a good ground to the back and then ground the tailgate or anywhere else you need to be sure a good ground is in place. I had a battery cable that would work find but as soon as you turned the key to start, nothing would happen. It was just dirty enough that when the high current from the starter engaged, it arced in the battery connection and would lose connection in less than 1/2 second. Such a simple thing but it would let me down on a quick trip to the corner store etc. The underneath on my '84 is very rusty and has undercoating on it too. I've taken off all the ground wires and then used a wire wheel to make sure all metal is shiny and then re-did them. Never hurts to clean them or have more. The defroster wire shouldn't be an issue as far as I know.

I'm sure you'll figure it out if your motor works with the dash switch.