V8 wiring problems - JeepForum.com
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post #1 of 6 Old 08-20-2005, 11:00 PM Thread Starter
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V8 wiring problems

I installed a Chevy 350 / 700R4 / NP207 into my 90 yj. I have plumbed everything in but am having problems finding what wires goes to what. All I have been able to determine is the alternator and heater motor. The distrubutor wire baffle me, I have a wiring diagram that looks like greek to me. It seem that I have 10,000 wires in my engine compartment but I'm sure I won't use half of them. Anyone?

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post #2 of 6 Old 08-22-2005, 03:08 PM
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Did your 90 have a 258?

I just got done rewiring the whole engine compartment harness of my 88, for exactly the reason you mention, with my weber and DUI I use about 1/4 of the wires in the stock harness, when I started this big project (lift, gears, engine rebuild, etc.) I decided to redo it all right.

I eliminated the emission computer, the ignition module, and the ecm. There are three harness in the engine compartment. The one that comes through the firewall in the middle (near the int/exh manifolds) is the emission computer that is located in the dash, behind the glovebox. You probably wont need any of that (ie mine is in my basement now). The other two harnesses (near the brake booster) are for the electrical system (dash sensors, main power for everything, etc.) and the headlight harness. Those two are secured with a nut, maybe 5/16 IIRC.

I gotta run now, but if you have specific questions I might be able to shed some light. I still have the 258, no V8 swap. The Chilton manual is a huge help, and its wiring diagram is 100% correct if you follow it.

Black '88YJ 4.2L
2.5" Skyjacker, 32x11.5s, 4.11s, Weber, HEI, etc.
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post #3 of 6 Old 08-22-2005, 08:04 PM
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We need some info on your Chevy motor. Injected? HEI? Smog? ect.....
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post #4 of 6 Old 08-24-2005, 05:13 PM Thread Starter
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It is a 90 Wrangler w/ 4.2 motor & NP231 Manual transmission. It had smog and all that. Other than that nothing special. I have a box with wires comming out of it on the drivers side and it used to attach to the inner fender (modual?) I have a group of wires and connections that mount on the battery mount, not sure if I need these or not. Yet another harnes that I put back through the firewall and re-connected it under the dash on the passenger side. It did have a distrubutor with a seperate coil. It was carburated.
I don't want to sound like an idiot, but this wiring is not my gig.
I completed an SOA w/ add-a-leaf. I have a Chevy 350 and 400R4 and made all of my mounts. This jeep was in boxes and now it's almost complete again with newly blasted and painted frame and components, freshly painted body and everything on the exterior. I am not half assing it. It's going to be a blast when it is done.
I am trying to reuse my stock guages if that is possible.
Thanks for any help.
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post #5 of 6 Old 08-24-2005, 05:29 PM
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Hey, I had a CJ7 that had a 350 planted in it. I took out all the wires but a few. I'm assuming you have a one wire distributor. Get a voltmeter and find out which one pumps out 12v only when on. It should also be on while the key is in the start position. I've seen several people get miffed because of this. Or you could just run a seperate switch for the ignition and have a kill switch in the process. Just use the key to turn the starter over.
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post #6 of 6 Old 08-25-2005, 12:03 PM
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Off the top of my head, wires in the main harness of interest:

orange/white w/single connector - heater motor
light green w/single conn. - oil pressure
purple w/cylinder like single conn. - coolant temp
(2) red w/ "O" conn. - main power, on all time
red/white w/ "O" - headlight power, on all time
yellow - ignition
green - ign. for starter
green - tach
green and orange wires w/gray conn. - a/c pressure switch
black/yellow - 4wd indicator
black - ground
That should at least get you started for matching things up to the wiring diagram.

You need the diodes (for the A/C) that are mounted near the battery, the relays are more emissions junk.

Black '88YJ 4.2L
2.5" Skyjacker, 32x11.5s, 4.11s, Weber, HEI, etc.
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