YJ wiring help!

toytech

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Club Member
Hi everyone,
I am getting close to having my YJ project running but have hit a snag:banghead:. I have a plug that I have no match to. 20160420_190110.jpg20160420_190116.jpg The plug sits even with the shifter on an AX15. Does anyone know if I am missing a section of the harness and if I am does anyone have one. It's for a 94 4.0l with the AX15. Thanks.
 

YJ_Driver

Commoner
Club Member
If no one knows off the top of their head I can look in my '94 FSM. Can you list all the wire colours?
 

aweber

This thread is :rainbow:
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Club Member
I imagine Dwayne or Scott would know.
[MENTION=86]dwcjwerfner[/MENTION]
 

toytech

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Club Member
The wire colours are Blue/Tan, Brown/Yellow, Black/Orange, Purple, Blue. I'm pretty sure the Purple and Blue are for the back-up light switch (which I don't have a proper plug for either). If I ground the Brown/Yellow then the motor cranks with the key but if I leave it off it won't. Not having the plug for the back-up light switch and the Starter only cranking when I ground that wire makes me think there is a sub harness that should be there.
 

2Greys

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Club Member
The wire colours are Blue/Tan, Brown/Yellow, Black/Orange, Purple, Blue. I'm pretty sure the Purple and Blue are for the back-up light switch (which I don't have a proper plug for either). If I ground the Brown/Yellow then the motor cranks with the key but if I leave it off it won't. Not having the plug for the back-up light switch and the Starter only cranking when I ground that wire makes me think there is a sub harness that should be there.

My guess (which this totally is) is the sub harness would be for Auto transmissions. The brown yellow is would be the park interlock
 

junkpile

Well-known member
Yes, PRNDL switch harness makes sense. Right number of wires but the shape of the connector doesn't look familiar.
 

2Greys

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I would figure it would probably have another small subharness which it connects to
 

YJ_Driver

Commoner
Club Member
So it is indeed for backup lamp and auto park/neutral detect, and the same connector is used for both trannies but for manual the matching harness will have a bypass wire for the later. I took a pic of the page and put it on Photobucket below, you have the top 6 pin connector. You'll want to short black/orange (ground) to brown/yellow, and connect your backup switch to dark blue/white and violet; I tried to mark this on the picture but it's kind of faint.

http://i1280.photobucket.com/albums/a481/RichnBarb/yj_tranny_harness.jpg
 

toytech

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Club Member
Thanks everyone for their assistance. YJ_Driver thank you so much for looking at the manual for me. I will get to making that sub harness in the next day or two. Now one more question...Has anyone ever had a crankshaft sensor that had to much voltage at the supply wire? It's supposed to be 8 volts and I have 11.2. My ground is good and i do have pulse when I rotate the crank it is just 7-11 volts when it's supposed to be 0-8.
 

junkpile

Well-known member
Ok so lemme get this straight, with the key on not cranking do you have 8v supply to the crank sensor? Or is it system voltage?
Also to confirm, you tested the sensors ecm supplied ground to battery + and had system voltage?
If both of these answers are yes then I think you have a bad crank sensor.
Keep in mind these old SBEC's don't like jobber crank sensors, mopar is your best bet.
 

toytech

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Club Member
I have battery voltage at the supply with the key turned on not cranking. I do have system voltage on the ground. So in this case do you suspect the sensor?
 

junkpile

Well-known member
Are you testing with the sensor unplugged? With it unplugged the engine harness side (key on) should show ground, 8v, & 5v. If so its the CPS.
If you have system voltage being supplied by the ecm then it's the ecm that's bad.
Is there a back story to this? What are we chasing, no spark or no injector pulse? Or?
 
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toytech

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Club Member
Testing plugged in. Backstory is...doing a 1994 4.0l swap into my project and currently have no spark and no injector pulse. I'm using the harness that came with the motor but an interior harness I bought for a 94 so that I wouldn't have to do too many wiring changes. I currently am trying to get this running without the body on. I have the column plugged in sitting across the frame. Would it be better to put the body back on and run my harness through the dash and fully install the steering column. (does the column need to be grounded?)
 

junkpile

Well-known member
Ok, so un-plug the crank sensor and check to see that the ecm is supplying the ground, the 8v, and the 5v. Those readings will at least tell you that the ecm is good.
If I remember correctly the injector pulse is controlled by the distributor pickup plate (black disc shaped Hall effect under distributor cap) so if you are missing both you may have another problem entirely. Possible ASD relay issue. Try jumping the ASD relay.
 

toytech

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Club Member
Thanks for the help, I will be trying these tests shortly. I will let you know how things go.
 

toytech

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Club Member
Ok so I fell like a total DumbAss!! While I was doing some checks tonight I found this 20160424_201354.jpg20160424_201423.jpg I think I know why I don't have spark! I guess while I have been so concerned with making sure all grounds were hooked up and all plugs connected correctly I forgot the basics:banghead: I did however find that with the crank sensor unplugged the pcm is sending too much voltage to the sensor. So it looks like I may have a couple of different problems.
 
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