XJ wiring harness

[Jeepjeff859]

So this spring I'm going to be starting a 350 swap. I have the engine , transmission , and transfercase ready to go but before I throw the new drivetrain in I want to tackle some wiring and comfort items.

My plan is to find a XJ wiring harness that have power door locks, windows, and all the other comfort items in it already.

My question is since I'm using a carb on the 350, will the ignition wiring be able to run the distributor and ignition coil or should I just go ahead and run a small fuse block with wires for the the distributor and coil?

I also plan on just adding length to the rear of the XJ harness and using it for the tail lights and fuel pump.

Can anyone think of other things I should do while I have the dash and wiring out?

[Marine1Texas]

It will be the same as any other HEI with carb. It can be tied in to the current or new XJ harness. With a HEI you just need to use the power that would go in to the old engines coil and it runs in to the new coil, or Pig tails for HEI. On the other side of the pig tail you have a tac wire that could be spliced in, however going from 6 to 8 your tac on your dash would need to be different.

 

HEI systems are one wire and basically just need the power turned on, just running thru ignition system (key), or a relay kicking on from the ignition system (key) if you want to not overload the wiring. While you have your dash out, you need to look at what gauge and how your going to fit all that in. none of the renix or HO gauges will work with what you have, but the fuel guage can be made to work. You will need to setup electric wiring for speedo ( or cable) tac, and if you want oil, temp, volts tied in. just things off the top of my head

[DirtyComanche]

Depending exactly what gauge cluster and wiring you use, you can reuse most of the gauge senders and make the gauges work.  You will need some NPT bushings and other pipe fittings, but it's not a terrible task.  For the tach you can buy a signal converter, or perhaps make your own (the factory did it with a potentiometer).

 

It's really going to matter what XJ harness you use, and other parts.  Keep in mind the power window wiring/switches changes over the years.

 

For the ignition power for the HEI I didn't use a relay, I just ran it straight from the ignition switch.  That is how GM did it for a very long time and the switch/column is essentially GM stuff.  A HEI MIGHT pull 20amps for a very short time during initial cranking, but they normally are only a few amps running.  That said, you could run a relay if you wanted, but it really isn't necessary.  12ga wire is recommended, some of the aftermarket harnesses and pigtails are 10ga though, however GM typically only used 14ga from the factory.

 

It's kinda up to you how far you want to go with this.  There is a ton of wiring that doesn't do anything useful, or can be clipped back or cleaned up, especially if you go to a stone aged engine.  Even on my XJ, which retained most features and a Renix injection system, I was able to cut out a massive amount of stuff, and that was without really getting into the body harness.

 

One thing though, if you tear your entire dash out doing all this stuff, look at your heater core and maybe change it while you're in there. :idea:

[Marine1Texas]

^ if you have the dash torn down, yes make sure your heater core is up to snuff.