No start or crank 4.0 swap - JeepForum.com
 
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post #1 of 13 Old 08-17-2017, 01:58 PM Thread Starter
MiguelGonzalez
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Location: Houston
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No start or crank 4.0 swap

I am just about finishing a 4.0 swap on a 91 yj and cannot get it to crank here is what everything came off of

engine tranny and tcase out of a 99 tj

Fuel rail 92 xj

pcm 93 auto xj

wiring harness off of a 93 yj

sensors all off of a 93 xj and a few from my 91 yj 2.5

whenever I turn the key I can hear a click over near where the starter is, I checked the volts to the starter and they are 11.7 I did the screwdriver trick on the starter and it that makes it work. Is there anything I'm missing, I have read that xj computers work on yj's and I couldnt find a yj one so I went for that. Am I supposed to move pins around or ground the Neutral safety switch or something? When I turn the key to on everything else thatI have checked works, lights, stereo, air. I do have the fenders off so maybe im missing a ground the is supposed to be connected there but I dont know.

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post #2 of 13 Old 08-18-2017, 09:22 AM
mike134
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1989 YJ Wrangler 
 
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You have 11.7 Volts on the SIGNAL wire to the starter with the key in START?

If the Jeep starts up with the screw driver, then your problem lies in the key circuit. Try changing your starter relay with the horn relay in the power distribution center. You can also check voltage at this relay to see if the key in the START position is sending the proper signal. If you have no signal voltage at the relay, then your problem may be with the ignition switch under the steering wheel.
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post #3 of 13 Old 08-18-2017, 11:50 AM
grapehead
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You have voltage to one or both posts on the starter when attempting to crank? does it run when you use the screwdriver trick?
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post #4 of 13 Old 08-18-2017, 01:57 PM Thread Starter
MiguelGonzalez
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Quote:
Originally Posted by mike134 View Post
You have 11.7 Volts on the SIGNAL wire to the starter with the key in START?

If the Jeep starts up with the screw driver, then your problem lies in the key circuit. Try changing your starter relay with the horn relay in the power distribution center. You can also check voltage at this relay to see if the key in the START position is sending the proper signal. If you have no signal voltage at the relay, then your problem may be with the ignition switch under the steering wheel.
No I don't have power to the signal wire with the key on start, only on the battery cable. I tried switching the starter relays and nothing happened. When somebody turns the key I can hear a click at the PDC but nothing else happens. How would I check the voltage at the relay?
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post #5 of 13 Old 08-18-2017, 02:05 PM Thread Starter
MiguelGonzalez
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Quote:
Originally Posted by grapehead View Post
You have voltage to one or both posts on the starter when attempting to crank? does it run when you use the screwdriver trick?
No I don't have power to the signal wire with the key on start, only on the battery cable. I tried switching the starter relays and nothing happened. When somebody turns the key I can hear a click at the PDC but nothing else happens. How would I check the voltage at the relay? The under dash harness is a 2.5 91 according to these diagrams there are a few differences at the bulkhead but I dont know if that would be enough to cause this. Top is a 94 yj pinout bottom is a 91

http://www.pirate4x4.com/forum/attac...m-bulkhead.jpg

http://img15.hostingpics.net/pics/61915291bulkhead2.jpg
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post #6 of 13 Old 08-20-2017, 01:36 PM
mike134
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You will look at the voltage at pin 86 on the starter relay socket (should be labeled on the bottom of the relay itself). One probe should touch the battery GROUND, and the other probe at 86 with a paper clip if needed.

Turn the key to START.

You should read 12 VDC at pin 86 (nominally, meaning it can be slightly higher or lower).

You should read 12VDC at pin 30 no matter what happens with the key.

Yo should read 12VDC at pin 87 no matter what happens with the key.

You should have continuity to ground on pin 85.
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post #7 of 13 Old 08-23-2017, 11:10 PM Thread Starter
MiguelGonzalez
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Quote:
Originally Posted by mike134 View Post
You will look at the voltage at pin 86 on the starter relay socket (should be labeled on the bottom of the relay itself). One probe should touch the battery GROUND, and the other probe at 86 with a paper clip if needed.

Turn the key to START.

You should read 12 VDC at pin 86 (nominally, meaning it can be slightly higher or lower).

You should read 12VDC at pin 30 no matter what happens with the key.

Yo should read 12VDC at pin 87 no matter what happens with the key.

You should have continuity to ground on pin 85.

Okay so I checked everything at the relay and I switched out the interior wiring harness for a 93 to match the outside harness, and that got the fuel pump priming. When I checked the starter relay I wasn't Getting any power to the starter signal wire still. At the starter relay I have two red/white wires that read 12 volts constantly at pin 30, one yellow/white wire at pin 86 that has 12 volts when key is turned to start, a blue/yellow wire at pin 85 that has 12 volts when key is turned and a green/red wire at pin 87 that reads .2 volts when key is turned. As I type this it looks like I either messed up with the readings on pin 85 or my ground is getting 12 volts on start... while my 87 is reading nothing...
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post #8 of 13 Old 08-23-2017, 11:33 PM Thread Starter
MiguelGonzalez
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Quote:
Originally Posted by MiguelGonzalez View Post
Okay so I checked everything at the relay and I switched out the interior wiring harness for a 93 to match the outside harness, and that got the fuel pump priming. When I checked the starter relay I wasn't Getting any power to the starter signal wire still. At the starter relay I have two red/white wires that read 12 volts constantly at pin 30, one yellow/white wire at pin 86 that has 12 volts when key is turned to start, a blue/yellow wire at pin 85 that has 12 volts when key is turned and a green/red wire at pin 87 that reads .2 volts when key is turned. As I type this it looks like I either messed up with the readings on pin 85 or my ground is getting 12 volts on start... while my 87 is reading nothing...
Update pins 85 86 and 87 all get 12 volts when I turn the key.
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post #9 of 13 Old 08-24-2017, 03:13 PM
mike134
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Sounds like your problem is the wiring from the starter relay to the starter solenoid. Should be the thin green wire on the starter that needs to be replaced.
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post #10 of 13 Old 08-26-2017, 02:47 PM Thread Starter
MiguelGonzalez
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Originally Posted by mike134 View Post
Sounds like your problem is the wiring from the starter relay to the starter solenoid. Should be the thin green wire on the starter that needs to be replaced.
I Figured it out, turns out the PO had set up a switch under the dash that had to be pushed in (ground switch?) to engage the starter relay, on top of that the outside harness had the ignition switch wire running through the bulkhead connector above the pcm, while the under dash harness had the ignition switch wire running through the 10 pin connector in the center of the firewall. I removed all the ground switch stuff and moved the ignition switch wire to the bulkhead and it cranked right up. The starter relay on my pdc is incorrect according to the diagram on the lid of the pdc it was supposed to be the 3rd one to the right if you are facing the windshield, so I was checking that one but after I traced back all the wires it ended up being the second from the right. Thanks for all the help to you guys! I hope this helps some people out in the future. I have no idea why the uner dash harness would not match the outside harness if they came off of the same model and year vehicle both 93 4.0s and why the PDC has the starter relay in a different position as it says on the lid diagram.
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post #11 of 13 Old 08-26-2017, 04:10 PM
mike134
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Was the ground switch some sort of anti-theft kill switch? Not a terrible idea to keep that in there.

Glad you got it running! Sorry we couldn't have been more help. It sounds like you have a lot of wiring nonsense You're going to have to stock up on the factory service manuals for multiple years.
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post #12 of 13 Old 08-27-2017, 02:53 PM Thread Starter
MiguelGonzalez
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Quote:
Originally Posted by mike134 View Post
Was the ground switch some sort of anti-theft kill switch? Not a terrible idea to keep that in there.

Glad you got it running! Sorry we couldn't have been more help. It sounds like you have a lot of wiring nonsense You're going to have to stock up on the factory service manuals for multiple years.
It was more of a push start type switch, no actually you were a great help the relay info you gave and everything was spot on I was just testing the wrong relay haha. Yea gonna have to get a couple of them I only have a 95 and none of my wiring or hardware is 95 except for the tub lol.
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post #13 of 13 Old 08-27-2017, 03:52 PM
mike134
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You have to learn everything you can about it, because if you get stranded somewhere, no shop can/will help you!

It is the curse of the old frankenjeep. Doesn't make too much difference though, how many shops can help to fix an 89 carbureted engine in 2017 anyway?
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