Help with 2.5 to 4.0 swap

Austin850

Austin850

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Joined
Jul 13, 2018
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13
Location
Pensacola, FL, USA
Help!! -Electrical-
I have a 1998 tj 2.5 auto I took the motor and transmission out and installed one from a Cherokee into my tj also replaced the 4 cyl harness with a tj 6 cyl harness so I now have a 2000 xj motor witch is coil on plug and computer out of the xj and it won’t start, I’m not getting spark or fuel pump I’m also not getting dash gauges or head lights but all my other lights work blinkers and all and I have a new headlight switch
 
glwood said:
This appears to be beyond forum guessing. Can you have it towed to a shop?
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X2

you are at the point where you are needing to trace power until you find out what is causing the problem. You can toss part after part untill you find it but that is going to cost a lot of money. But you need to know exactly where the power is getting lost.
It might be something stupid like you didn't reconnect a plug or something more technical like a vin number programmed into the pcm (not sure when they started doing that).
The only other thing i would check is the compatibility of the gauge cluster from the 98 to 2000 model. Sometimes they change the way they communicate with the computer. Not exactly aure when the tj cluster changes. Plags and harnesses are the same for the most part. But i thought i read somewhere that tit changed.
 
Well, first things first, you're going to need the computer that came from that vehicle.

The other thing I'd check is to make 100% certain your battery is good.

Aside from that, there's so many things here that could be wrong it's beyond guessing, seriously... Being as though you did a complete swap, the smartest thing you can do in a situation like this is to sleep on it, then go back at it in the morning after some rest. Go through everything bit-by-bit and make sure you didn't miss any connections.

It's usually the simplest thing that ends up being the answer.
 
Chris said:
Well, first things first, you're going to need the computer that came from that vehicle.

The other thing I'd check is to make 100% certain your battery is good.

Aside from that, there's so many things here that could be wrong it's beyond guessing, seriously... Being as though you did a complete swap, the smartest thing you can do in a situation like this is to sleep on it, then go back at it in the morning after some rest. Go through everything bit-by-bit and make sure you didn't miss any connections.

It's usually the simplest thing that ends up being the answer.
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Hey , so I have a new battery I’m starting to think the dealer needs to program the computer
 
Boinked said:
X2

you are at the point where you are needing to trace power until you find out what is causing the problem. You can toss part after part untill you find it but that is going to cost a lot of money. But you need to know exactly where the power is getting lost.
It might be something stupid like you didn't reconnect a plug or something more technical like a vin number programmed into the pcm (not sure when they started doing that).
The only other thing i would check is the compatibility of the gauge cluster from the 98 to 2000 model. Sometimes they change the way they communicate with the computer. Not exactly aure when the tj cluster changes. Plags and harnesses are the same for the most part. But i thought i read somewhere that tit changed.
Click to expand...
I’m gonna check the dash next thanks
 
Austin850 said:
I’m also not getting dash gauges or head lights but all my other lights work blinkers and all and I have a new headlight switch
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After reading the post again this has me confused. The headlights don't run through the computer. This might be a separate issue. But then again it might be somehow connected. If you have a multimeter check and trace this down. It should be easy. Maybe if you find this problem it might be connected to the others. IE bad connection
 
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Boinked said:
After reading the post again this has me confused. The headlights don't run through the computer. This might be a separate issue. But then again it might be somehow connected. If you have a multimeter check and trace this down. It should be easy. Maybe if you find this problem it might be connected to the others. IE bad connection
Click to expand...
So I got power to the fuse box under the hood for the headlights and at the sockets I got nothing but ground at the sockets
 
Austin850 said:
Help!! -Electrical-
I have a 1998 tj 2.5 auto I took the motor and transmission out and installed one from a Cherokee into my tj also replaced the 4 cyl harness with a tj 6 cyl harness so I now have a 2000 xj motor witch is coil on plug and computer out of the xj and it won’t start, I’m not getting spark or fuel pump I’m also not getting dash gauges or head lights but all my other lights work blinkers and all and I have a new headlight switch
Click to expand...
You might get a harness and computer from a 98 tj auto and proper sensors electronic ignition etc for closer match you are fighting to many variables. Just because you have a harness that plugs in doesn’t mean it is compatible manufactures make changes all the time sometimes even mid year
 
Austin850 said:
So I got power to the fuse box under the hood for the headlights and at the sockets I got nothing but ground at the sockets
Click to expand...
what about the input and out-put of the headlight switch. if you have voltage out of the headlight switch then you just need to trace that one wire to the headlight. there has to be a connector of cut wire somewhere.
 
Davidtj said:
You might get a harness and computer from a 98 tj auto and proper sensors electronic ignition etc for closer match you are fighting to many variables. Just because you have a harness that plugs in doesn’t mean it is compatible manufactures make changes all the time sometimes even mid year
Click to expand...
The wiring harness is different from a 98 to 2000 there not even close and going from 2.5-4.0 plus everything is plugged in already and I’m not re wiring this Jeep again it’s a 4.0 with a 4.0 harness there shouldn’t be a problem where it all plugs into the computer is under the hood so I’m not to sure why I can’t get spark or fuel pump to kick on
 
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