Tachometer wiring

I just got a factory tach (thanks wroughtwhang) and I'm having a little trouble figuring out how to connect it to the existing wiring. I assumed that the wiring harness would have plug ins to connect but since my Jeep didn't come with a tach, apparently not. In the wiring diagrams, all I see are two wire connections, both red with white tracer, one to the ignition switch and the other to positive fuse block. The tach has 4 wires, 2 red/w 1 black and 1 orange....

TMI - just need to know how to connect the 4 wires attached to the tach.

Thanks

 

My best guess is, one red draws power from the ignition switch, one red powers the light in the tach (connects to the headlight switch), black probably goes to the NEG side of the coil and i have no idea where the orange one goes. Wish I could be more help.

 

Just finished swapping a 4.0 from a 98 grand cherokee into my brothers 83' CJ7 sounds about like what I ran across with his tack. no idea why it worked, but The red wires go to ign on. (one of which also ends up going to the ign module) black is ground and orange is guage lights. This was no longer compatable with the newer system, (or at least I couldn't get it to work). He bought a tach from Hesco that matched the original guages and wired in the regular tach way with a pulse sense wire from the coil. In that year a 4 cyl wired the regular way and 6 cyl wired the wierd way. both connectors were already in the harness behind the dash, so we were able to utilize the 4 cyl connector to make it work.

 

Probably the only helpful thing I can contribute would to try to determine what year the tach was factory original for. I wasn't aware of a factory (non dealer installed) tach until at least 1976, at the earliest. I may be misrememberin, but someone will correct me right quickly if I am. Anyway, If you could narrow down the year it was factory installed, then you could possibly track down a wiring diagram for that year. I'm amazed at how accurate my Chilton's wiring diagram is for my 75, turned out to be by far the most usefull page in the book.

That being said, I just installed a sunpro cheapie tach in the irritant.

Green- went to my dist (DUI)
Red- went to my fuse block to a terminal that was hot when the ignition was in run position, not hot in acc/start.
black- to a ground
white- T's into any wire that the headlight dash dimmer controls.

Thems my wires, and I'm stickin' to em.

 

Yeap, two wires are for the bulb (one hot, one ground) and two wires are for the tach. With a stock points set and what not, the two tach wires get spliced in series into the line that goes from your ignition switch to you ignition coil. So I guess clip your line at the ignition coil and run it up to the tach, then run a new line from the other side of the tach back to the ignition coil. Thats how I did mine.

 

Strider got it right only you don't have to run extra wires or cut anything if you have the factory wiring. Crawl under the dash with your light and look for a heavy red wire attached to the ignition switch ( marked # 13 if you are luckey enough to have numbers on the wires) this wire has a black plastic connector in it for no apparent reaseon. This is where you disconnet the wires and insert the red leads from the tach. The tach and ignition connectors are keyed (male to female) so if you don't cut anything you can't get them backwards. The black lead is for ground and the orange one goes to the dash light circuit. Hope this helps
WW,