Gr8Dain's 4.0/aw4 swap from a 97 XJ

gr8dain

Scrambler Junkie
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City
Ashburn
State
VA
The fan looks a bit too close. IIRC, on my red Scrambler that now has a 4.0 with 4.2 front accessories, I used a 1979 258 fan clutch because it was about 1" shorter then the 1983 version. BUT, I am running a 4.2 water pump. I would try to get a bit more clearance if you can.
I can try to slide the radiator inside the grill like I had it before. That gained about 1/2” of clearance.
 

gr8dain

Scrambler Junkie
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City
Ashburn
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VA
Have I mentioned that I hate wiring? Well I had some time, so I went out in the coldish to lay out the wiring harness and connect what I could. Most went well. But I have a couple of plugs on the harness that have nothing to connect to like the oil pressure sender and the crank position sensor. And then I have some plugs that don’t match with my accessories, like the alternator, the fuel pump and the speed sensor. But I am making progress
 

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gr8dain

Scrambler Junkie
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Ashburn
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VA
I put the computer on the drivers fender based on the length of wiring in the harness. I need to determine the right places for the fuse block and the trans control module. I ran the data link and brake sensor wiring through the hole that used to be there for the clutch rod. I will find a place to put it under the dash
 

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gr8dain

Scrambler Junkie
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Ashburn
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VA
A little bummed. I bought an oil pressure switch for the 4.0. Selected one for a 1997/1998 harness as that was what I should have (ordered from Hotwire) but when the part finally arrived from Rock Auto (USPS is super backed up) and went to install it today, it does not match the connector on the harness. Looked it up and the connector is for a 2000+ XJ. Grrr. So now that and the alternator are wrong. I guess it is my fault though as the harness I sent to hotwire as the “old harness” was not the one from the donor. I was told it was from a 1998 when I bought it from another person, but I guess not. And now I have discovered which connectors on the harness are different. The alternator and the oil pressure switch. Damn. Now I need to get an oil pressure switch for a 2001ish. And I will probably get a new alternator as well.

I would like to know if I can just cut the plug off of the wired for the alternator and add ring terminals to the wires, but I don’t know if it matters which wire goes to which post. Anyone know if it just needs to make a circuit? I would hate to have it wrong and fry something.
 

jpnmaine

Active member
CJ-8.com Member
City
East Wilton
State
ME
You can look up the type of connector needed. Get the pins and connector male/female ends. Break the connector that you want to change apart. I used a small flat head screw driver ground down to fit into each connector pin slot. Pin has a barbed end that the screw driver pushes on to release from connector. Solder new pin and push into new or used connector. Did a lot of that on the 5 EFI conversion. Utilized the fire wall electrical connector so the 94 engine harness had pin spots to connect up to/pass through...ignition, fuel pump relay, etc. Other connectors on the 5's electrical harness modified the same way. A little 78 and 94. Liked the 94's weather tight connectors so used them more. So the alt connector was a 94 passing through the fire wall connector to the 78 gauge. Just poured over the electrical schematic a little more on the alt and did not have a problem. The oil sender from the 258 was screwed into an oil port on the 94 motor. Utilized existing oil sending wire. Long explanation and not really answering your question...
 
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FLCJ8

Legacy Registered User
City
Palm Bay
State
FL
A little bummed. I bought an oil pressure switch for the 4.0. Selected one for a 1997/1998 harness as that was what I should have (ordered from Hotwire) but when the part finally arrived from Rock Auto (USPS is super backed up) and went to install it today, it does not match the connector on the harness. Looked it up and the connector is for a 2000+ XJ. Grrr. So now that and the alternator are wrong. I guess it is my fault though as the harness I sent to hotwire as the “old harness” was not the one from the donor. I was told it was from a 1998 when I bought it from another person, but I guess not. And now I have discovered which connectors on the harness are different. The alternator and the oil pressure switch. Damn. Now I need to get an oil pressure switch for a 2001ish. And I will probably get a new alternator as well.

I would like to know if I can just cut the plug off of the wired for the alternator and add ring terminals to the wires, but I don’t know if it matters which wire goes to which post. Anyone know if it just needs to make a circuit? I would hate to have it wrong and fry something.
I found a couple connector pin outs (the wiring is also available) for TJ's.
Do these match your harness and/or sensor and alternator?

1998 gen.PNG 1998 oil.PNG 2000-2001 gen.PNG 2000-2001 oil.PNG

If so, it should be fairly easy to determine what needs to be modified.

How is the oil pressure sensor supposed to drive the stock oil pressure gauge?
Is the gauge on the XJ also controlled via the PCM like the TJ?
 

gr8dain

Scrambler Junkie
LIFETIME
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City
Ashburn
State
VA
I found a couple connector pin outs (the wiring is also available) for TJ's.
Do these match your harness and/or sensor and alternator?

View attachment 90063 View attachment 90064 View attachment 90065 View attachment 90066

If so, it should be fairly easy to determine what needs to be modified.

How is the oil pressure sensor supposed to drive the stock oil pressure gauge?
Is the gauge on the XJ also controlled via the PCM like the TJ?
Thanks. I am following the pin outs for the alt/generator. I will look more at the oul pressure diagrams. As for the signal, I believe that the XJ does feed the gauge through the pcm. Not sure if it will work the gauge in my CJ. We will find out.
 

FLCJ8

Legacy Registered User
City
Palm Bay
State
FL
Thanks. I am following the pin outs for the alt/generator. I will look more at the oul pressure diagrams. As for the signal, I believe that the XJ does feed the gauge through the pcm. Not sure if it will work the gauge in my CJ. We will find out.
I seem to remember that usually what is done on a swap is a "T" is installed and the 4.0 sensor goes to the PCM and the 4.2 sensor goes to the factory gauge.
It was years ago when I looked into it and haven't done mine yet but I'm sure many here have and will know.

If you confirm that the pin out diagrams I posted are the same as what you are dealing with I can post the actual wiring diagrams for each as well.
 

jpnmaine

Active member
CJ-8.com Member
City
East Wilton
State
ME
I used the 258's oil sending unit. Can put a Tee in to hook it up or in my case used an existing oil port plug to install. Not sure if the pcm would pass through to the gauge at the right voltage. Easier just to use the old oil sending unit.
 

gr8dain

Scrambler Junkie
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City
Ashburn
State
VA
We will see. I will deal with it after I get it started. But I am assuming that I will need a T and will have to see what the signal is sent out at.
 

gr8dain

Scrambler Junkie
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City
Ashburn
State
VA
Weather was decent so I got out i the driveway and worked on the Scrambler some. Wired the power to the fuel pump, chose a spot for the coolant overflow, secured the air cleaner, put the battery in and connected the power to it.

I am not getting power where I need it though. I tried the key to see if I could hit the lights, get the fuel pump going and try the horn. I hear the relay click for the horn. But no horn. No fuel pump action. And no lights at all. Inside or out.

But the fuel gauge is reading (all the time) and the voltmeter jumps to 12 when I turn the key to accessory. I accidentally turned the key too far and they starter bumped, so that is something. Oh and when I reached under the dash to grab the fuse panel (I was holding it while I pushed the two sides back together), this 12v 15 amp metal “fuse” fell and hit the floor mat. Any idea what it is for? Was it in the fuse panel and fell? I don’t remember it being there, but it may have been.
 

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Randyzzz

Blown Budget
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Redmond
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OR
That’s a breaker, most likely for the headlamp power feed.

I’m about to start building my harness tomorrow...
 
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