mfpdm Posted April 26, 2009 Share Posted April 26, 2009 I've spent way to much time fighting this today so I figured I'd take a break and ask. I'm using a 89 XJ wiring harness in the engine and under the dash. I've got both doors wired up with the cross body harness that connects them. However, this is where I'm kind of stumped. They connect to each other but there is no connector to the harness from the dash harness. I'm guessing that it is one from the harness for the rear of the XJ. So long story short, I've search the board and found no specific threads on just exactly what wires from the XJ dash harness are needed to plug into the MJ rear harness. Detailed write-ups, notes from when you did it, pictures, or what not will help. I have the wiring diagrams but they are more trouble than their worth. What I would like to do is make a pigtail that will connect the XJ harness to the MJ harness so I don't have a ton of splices and so the process can be reversed if I come up with or need a new harness. Once done I'll do a complete write-up with pics seeing how this is a common swap for the dash harness. :cheers: Link to comment Share on other sites More sharing options...
Akula69 Posted April 27, 2009 Share Posted April 27, 2009 I'm a little confused. I understand you are trying to slpice the rear MJ harness to the XJ harness....but are you also trying to connect the door/cross body harness to the dash harness? If so, the door/cross body harness on the truck I stripped a while back was connected under the driver's side kick plate. I can't help you with the Mj rear harness splice...sorry. Link to comment Share on other sites More sharing options...
mfpdm Posted April 27, 2009 Author Share Posted April 27, 2009 Sorry for any confusion. The cross body harnesss is what started the whole wiring issue. Without the rear XJ harness, the cross body harness gets no juice. So it brought me to the point which I knew was coming and that was how to make a XJ dash harness work with the rear MJ harness. I've figured out the power that supplies the door locks, windows, and mirrors. However, I'd rather figure out the whole thing before I piece mill it together so I can make pigtails using the leftover rear XJ harness and MJ dash harness. :cheers: Link to comment Share on other sites More sharing options...
chicofuentes0224 Posted April 27, 2009 Share Posted April 27, 2009 I'm sorry M but I'm still confused. Are you trying to get the things like fuel pump and rear tailights to work? Link to comment Share on other sites More sharing options...
mfpdm Posted April 27, 2009 Author Share Posted April 27, 2009 Yep. Everything from the dash connectors back. Basically, the XJ has 2 main connectors that supply everything from the dash back. Among them is fuel pump, sending unit, tail lights, power for the doors stuff, etc... The MJs only have one main connector and another that is flat vs square like the XJs. I figured as many that have done the 2.5 to 4.0 swap, that someone would have tackled this and hopefully took some notes down. :thumbsup: :cheers: Link to comment Share on other sites More sharing options...
chicofuentes0224 Posted April 27, 2009 Share Posted April 27, 2009 M, I had to do this when I replaced my dash and engine harness due to a electrical fire. If nobody has replied by tonight I'll start taking pictures and notes of what I did. It was a real pain to get everything to work right but I somehow figured it out. I'll get back to you 2 nite. Link to comment Share on other sites More sharing options...
troy6187 Posted April 28, 2009 Share Posted April 28, 2009 I went thru this when i put everything from the dash forward from a 94 xj in my 88 mj. I made a pigtail just how u decribed so i did not need to cut either harness. If u have wiring diagrams and the old harness' to rob the needed conne tors from your set. You will also need to run a wire from the brake light switch to the turn signal switch. Mj's have combined brake and turn lights where as xj's have separate lights. All you do is run a wire from the. Brake light wire in the plug going to the rear to the body side of the plug for the turn swich. I'm typing this on my i fone so i can't post pics. If you really need me to i can pull the jumper harness and tell you wire by wire but that is gonna be alot on the fone. That said, i will do what i can to help out a fellow jeeper and especially a fellow mj addict. Link to comment Share on other sites More sharing options...
mfpdm Posted April 28, 2009 Author Share Posted April 28, 2009 I went thru this when i put everything from the dash forward from a 94 xj in my 88 mj. I made a pigtail just how u decribed so i did not need to cut either harness. If u have wiring diagrams and the old harness' to rob the needed conne tors from your set. You will also need to run a wire from the brake light switch to the turn signal switch. Mj's have combined brake and turn lights where as xj's have separate lights. All you do is run a wire from the. Brake light wire in the plug going to the rear to the body side of the plug for the turn swich. I'm typing this on my i fone so i can't post pics. If you really need me to i can pull the jumper harness and tell you wire by wire but that is gonna be alot on the fone. That said, i will do what i can to help out a fellow jeeper and especially a fellow mj addict. Bingo. :clapping: I don't want you to try and do that on your phone. However, if you could maybe write it down and fax it or mail it, I'd make it worth your time. Maybe a picture of the pigtail would be nice too. Only thing that may throw a wrench into it is that being a 94 XJ it's an H.O., I'm thinking that the wiring change from the Renix era and it may not help me with this 89 XJ to 88 MJ issue. I've sat down with the old harness from the XJ and basically the crap that was above the left rear wheel kind of has me stumped. The three relays which as I understand from the diagram is for the power locks, left and right turn signals, and brakes lights for the towing harness. Looking at the MJ diagrams, these don't exist. :dunno: Again, please don't try and do that on the phone thingy. It would have taken me an hour just to write what you did above. :dunce: :cheers: Link to comment Share on other sites More sharing options...
troy6187 Posted April 28, 2009 Share Posted April 28, 2009 The only part of the xj rear harness you will need are the plugs that plug into the dash harness and about a foot of wire... The same for the mj dash harness. You said that you had the wiring diagrams so as long as they are accurate, it shohld be fairly simple to put together. and you are right, because mine is from a ho it will be a little different than yours. I'm off work tomorrow and need to work on it anyways, so i will pull the jumper out And post the details. I can't promise any pics but ill try. And typing all this on the fone isnt too bad... Touchscreen and a fullkeyboard help. :) Link to comment Share on other sites More sharing options...
mfpdm Posted April 28, 2009 Author Share Posted April 28, 2009 The only part of the xj rear harness you will need are the plugs that plug into the dash harness and about a foot of wire... The same for the mj dash harness. You said that you had the wiring diagrams so as long as they are accurate, it shohld be fairly simple to put together. That is what I like hearing. The rear harness on the XJ has some weird crap in it. I think that is what was stonewalling me from doing what I thought was right. and you are right, because mine is from a ho it will be a little different than yours. I'm off work tomorrow and need to work on it anyways, so i will pull the jumper out And post the details. I can't promise any pics but ill try. And typing all this on the fone isnt too bad... Touchscreen and a fullkeyboard help. :) :cheers: :cheers: :cheers: :cheers: :cheers: :cheers: :cheers: :cheers: :cheers: :cheers: :cheers: :cheers: I appreciate your efforts good sir. :bowdown: Link to comment Share on other sites More sharing options...
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