I've swapped in a 4.0L and AX-15 out of a '96 XJ into my '85 CJ-7, and I'm now in the process of getting the damn thing wired. I have the dash completed with a new Centech wiring harness, but I need some help with the motor. I have the factory harness and ECU, and all of the sensors are wired. I've swapped in the oil pressure and coolant temp switches from my 258, so I'm pretty sure those will work. Here are my questions:

The Centech harness is designed for a Delco alternator, and has the two prong plug that is supposed to go into the outside of the alt. case, can I disregard this plug, and just go straight from the battery terminal on the alt. to the large battery post on the starter selenoid?

To power the Centech fuse panel, can I just run a heavy gauge wire from the bat. post on the starter to the fuse panel?

The Centech harness has a "Start" wire running from the firewall, does this need to go to the bat. post on the starter selenoid? I've called Centech, but didn't know. (Great service otherwise.)

I'm running an external fuel pump from Mallory, that requires a 12v keyed on source, and I want to use the factory fuel pump relay. Does anybody know which wire at the relay box powers the fuel pump? I can't figure which one it is from the schematic.

That's about it for now. Thanks for the help.

Originally posted by Medic

The Centech harness is designed for a Delco alternator, and has the two prong plug that is supposed to go into the outside of the alt. case, can I disregard this plug, and just go straight from the battery terminal on the alt. to the large battery post on the starter selenoid?


Normally you need that second (white) exciter wire with a diode to protect your igniton electronics.

Originally posted by Medic

To power the Centech fuse panel, can I just run a heavy gauge wire from the bat. post on the starter to the fuse panel?


Bad idea. Run from Bat to 80 Amp Maxi Fuse and then to fuse panel and leave the started on a seperate curcuit.

Originally posted by Medic

The Centech harness has a "Start" wire running from the firewall, does this need to go to the bat. post on the starter selenoid? I've called Centech, but didn't know. (Great service otherwise.)


Batt to "B" post and the purple from the starter switch to the selenoid's "S" post on the old fashioned fender mount units.

That's all I can (try to) help from just my experience with a Painless and MPI kit :p

[QUOTE]Originally posted by Jaffer
[B]

"Normally you need that second (white) exciter wire with a diode to protect your igniton electronics."

Is this taken care of by the factory (XJ) harness?


"Bad idea. Run from Bat to 80 Amp Maxi Fuse and then to fuse panel and leave the started on a seperate curcuit."

So you're saying I should run the fuse block power directly from the battery?


"Batt to "B" post and the purple from the starter switch to the selenoid's "S" post on the old fashioned fender mount units."

That helps. The starter doesn't have the fender mount selenoid, it's attatched to the starter case, and there's no "S" or "B" posts marked, but that should be easy to figure out.

Thanks for the help Jaffer.

BTT

I am finishing my swap and have hit a probably simple wall... How do I wire my 84 CJ7 to hook up to a 96 4.0L alternator???:confused: Can anyone help?

Thanks...

Well I just did basically the same thing; a 95 XJ 4.0/AW4 into my 84 CJ7. I've got the alldata schematics and the fuel pump wire is 14AWG DarkGreen/White, but that's for a 95.

Don't know about your Centech dash. ;)

On my 94 4.0 swap I just used the stock 4.0 starter and let the 4.0 computer run it. I made all my connections at the firewall. I only ran starter, ignition, NSS, Constant Power and Fuel Pump. I had the whole harness, comp, PDC and basically just spliced the two firewall harnesses together. Ran perfect. Search under my name Rob Kosinski for a ton of info.


Good Luck,

RK

Hey Rob good to see you again! heard you've made a few mods to your rig since the last time we talked.

As for Medic's question, you didn't state this but I'm going to assume that you are swapping the FI and accessories from the 4.0L as well. That being assumed, you should use the donor 4.0l harness for the charging system, not the centech harness. The PCM monitors alt output. I've cut out about 3/4 of the centech harness for the engine.

DG/W is the correct wire for the fuel pump. This wire will be found at the PDC.

Good luck