Thinning an OBD1 wiring harness

[GWag87]

I'm a fsj owner in the process of swapping a 94 4.0 into my 88 grand wagoneer. I need some help with the wiring harness.

I've heard things like "5 wires to fire" and thinning the harness to run in a buggy.

My old Jeep is pretty simplistic and I'm not trying to over complicate this project. I'm looking for a wiring diagram or some advise on how to get this motor fired up.

Some info that may be important to consider. I'm bolting the 4.0 to the tf727 that came in my Jeep. Plan on running the hesco cps sensor relocator. I have a computer from a 5spd wrangler obd1 type. My 360 is already running the xj style starter. If yall need more info just ask.

I'm a regular on the fsj network and they handle all my fsj ?s . I joined here to get help with my motor swap and solid 4.0 info. All help is much appreciated

 

[IdahoEagle]

Why not use the AW4 at the same time and get a strong, durable overdrive transmission and not have to use a conversion style CPS? I'm also a fellow FSJ'er, I've owned many over the years and have been a Jeep mechanic for over 20 years...

 

[GWag87]

I'm running a 999 offroad skid plate and X member. Designed to work with the 727. I may switch later on but for now it's the 727.

Any advise on wiring?

 

[souske]

Swapped a 96 obdII into an xj.

Label everything.as it comes.out, and draw your own.notes.

To thin things out, start looking for plugs you dont plan on using , chase em up and clip em.

Sorry no easy tricks. On the bright side, you will know your writing very well when you're done

 

[GWag87]

has anyone heard "5 wires to fire" for an obd1 4.0? Or is this Internet folk lure

 

[souske]

Cps is three wires, the coolant temp is four, three more for distributor, two more for the coil.

I.dont think it will run with only 5 wires hooked up

 

[GrimmJeeper]

Paging Cal!

I'm sure the OBD I harness in the team naxja rig is as minimal as it gets.

 

[shelbyluvv]

When I did my OBD-I 5.2 Magnum swap it was probably only 4 or 5 wires to get it to run. I remember a couple grounds and a couple hot wires to the PDC and bulkhead connector on the firewall.

I am using a 93 ZJ engine harness tired into a 94 XJ dash harness. The power goes from the battery, to PDC, to the ECM and into the bulhead connector. Once I dug into the wiring it became really easy to figure out what I needed and didn't.

Get a factory FSM for your year donor and the FSJ receiving the engine. Once you figure out what wire is what in both bulkhead connectors you can then figure out what you need to swap around to power the fuel pump, NSS and other things on the interior side of the firewall.

OBD-I is really easy to make work as long as you have a factory engine harness. Don't let the 60 pin ECU connector scare you. Most of those are just sensor, injector and ground wires. They will be powered from the PDC.

 

[cal]

I was gonna say, I don't have an easy answer here (we don't run an OBD1 setup) but this should be pretty simple. if only someone would PM you with the FSM's for those rigs..

 

[GWag87]

Thanks for the info. That gives me a place to start. I'm sure I will have more questions as I get deeper into the wiring.

Right now I'm waiting on a flex plate and fsj i6 motor mounts

 

[Hoooper]

Cps is three wires, the coolant temp is four, three more for distributor, two more for the coil.

I.dont think it will run with only 5 wires hooked up

x number of wire hookup doesnt relate to the number of total wires on the engine, it relates to the number of wires needed outside of the engine wiring harness. A 3 wire hookup might mean starter signal wire, "on" wire, and fuel pump. 5 wire hookup probably includes start, run, b+, ground, and fuel pump.