Question about wiring harness connectors on firewall for 98 to 02 body swap

Daniel597

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Okay guys. I need some help here. What exactly are these connectors for? In case the picture isn’t good enough, these are the two connectors located on the top of the firewall right in the middle. These are the only two plugs that seem to be different from my 98 to the 02 body I’m trying to swap onto my frame. I’ve checked the FSM and I am at a loss as to how to even read the thing. I’ve searched other threads and I’ve come up with nothing. Any help here would be appreciated as I have no idea how to resolve this issue without swapping the entire body harness from my 98 to the 02, which I would like to avoid if at all possible. Thanks in advance!
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Swap the entire body harness including behind the dash. To my understanding that is what you need to do to solve this.

The wiring harnesses (dash and engine harnesses both) need to match up and be from the same vehicle or at least the same year of vehicle.
 
Swap the entire body harness including behind the dash. To my understanding that is what you need to do to solve this.

The wiring harnesses (dash and engine harnesses both) need to match up and be from the same vehicle or at least the same year of vehicle.
So this means pulling the dash out and swapping everything? Will it be a direct swap from the 98 to the 02? Obviously I know that the HVAC controller is different. What about the blower motor wiring, and everything else?
 
So this means pulling the dash out and swapping everything? Will it be a direct swap from the 98 to the 02? Obviously I know that the HVAC controller is different. What about the blower motor wiring, and everything else?
I’m going to tag @mrblaine in this. He’s done enough of these swaps that he probably has a much more accurate answer than I will.
 
The only other option would be to research in the 8W section in the FSM between the 98 and 02; verify pin outs and wire colors in those connectors to ensure where they come from and where they go and rewire according to what is needed.
A friend had to do that on a 1998 XJ when swapping in a 5.9L engine from a Dodge.
 
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Okay guys. I need some help here. What exactly are these connectors for? In case the picture isn’t good enough, these are the two connectors located on the top of the firewall right in the middle. These are the only two plugs that seem to be different from my 98 to the 02 body I’m trying to swap onto my frame. I’ve checked the FSM and I am at a loss as to how to even read the thing. I’ve searched other threads and I’ve come up with nothing. Any help here would be appreciated as I have no idea how to resolve this issue without swapping the entire body harness from my 98 to the 02, which I would like to avoid if at all possible. Thanks in advance!View attachment 238316
If you are trying to swap an 02 tub onto a 98 chassis and keep the 98 motor, that will require moving the 98 harness into the tub. The problem is the 98 runs a distributor and the 02 runs the coil on plug system.

Typically the reason to swap the dash harness as mentioned above is for the 03 up to get the Rubi locker switch and or the OD off switch for the auto. Then you have to swap the engine/chassis harness to get or delete the wiring for the TCM for the 03-04. Same for the 05-06 but to get or delete the PCM plug for the auto that plugs into the PCM.

There may be a need to do the dash harness for the early HVAC controls and I can verify that if needed but not 100% if the connectors are the same right now.
 
The only other option would be to research in the 8W section in the FSM between the 98 and 02; verify pin outs and wire colors in those connectors to ensure where they come from and where they go and rewire according to what is needed.
A friend had to do that on a 1998 XJ when swapping in a 5.9L engine from a Dodge.
The ass kicker is the difference between the distributor and the coil on plug firing which uses 4 wires. 1 power and 3 switched ground for each of the 3 coils.
 
If you are trying to swap an 02 tub onto a 98 chassis and keep the 98 motor, that will require moving the 98 harness into the tub. The problem is the 98 runs a distributor and the 02 runs the coil on plug system.

Typically the reason to swap the dash harness as mentioned above is for the 03 up to get the Rubi locker switch and or the OD off switch for the auto. Then you have to swap the engine/chassis harness to get or delete the wiring for the TCM for the 03-04. Same for the 05-06 but to get or delete the PCM plug for the auto that plugs into the PCM.

There may be a need to do the dash harness for the early HVAC controls and I can verify that if needed but not 100% if the connectors are the same right now.
So you don't have to swap the entire body harness? Just the stuff behind the dash? Is the fuse box under the driver side of the dash required to swap? I cant figure out how on earth you would pull out the whole harness anyways with a fuse box on both sides of the firewall. Sorry for so many questions, I'm just super lost right now.
 
So you don't have to swap the entire body harness? Just the stuff behind the dash? Is the fuse box under the driver side of the dash required to swap? I cant figure out how on earth you would pull out the whole harness anyways with a fuse box on both sides of the firewall. Sorry for so many questions, I'm just super lost right now.
What are you trying to swap?
 
What are you trying to swap?
I guess I should've provided more details of what I'm trying to do here. I have a 98 frame with a 2.5 liter 5 speed. I'm trying to swap on an 02 tub I bought that is complete.The 02 came off of a 4.0 5 speed. The 02 tub had the entire wiring harness in tact, including the engine harness. I already took out the engine harness that consisted of the two right side plugs on the ECU. Now I'm trying to figure out what else I need to do to make sure everything will work. I still have my engine wiring harness and computer from my 98. It's the 3rd plug on the left side of the ECU that is concerning me.
 
I guess I should've provided more details of what I'm trying to do here. I have a 98 frame with a 2.5 liter 5 speed. I'm trying to swap on an 02 tub I bought that is complete.The 02 came off of a 4.0 5 speed. The 02 tub had the entire wiring harness in tact, including the engine harness. I already took out the engine harness that consisted of the two right side plugs on the ECU. Now I'm trying to figure out what else I need to do to make sure everything will work. I still have my engine wiring harness and computer from my 98. It's the 3rd plug on the left side of the ECU that is concerning me.
The 6 cylinder and 4 cylinder are going to require different engine harnesses even in the same year. I'll try to figure out the 3 plug tomorrow.
 
You are going to have to swap the 98 harness and cluster into the 02 body. The communication bus changed from CCD to PCI in 2000 and that will stop the gauges etc. from working.
So does that mean everything behind the dash? Or just where the stuff runs in from under the hood? I’ve managed to separate the stuff under the hood from the fuse block under the dash. Or is that what you mean changed?
 
So does that mean everything behind the dash? Or just where the stuff runs in from under the hood? I’ve managed to separate the stuff under the hood from the fuse block under the dash. Or is that what you mean changed?
Maybe the harness on the firewall can stay but the one on the dash has to go. Pull the dash, much easier to see which is which. If the one on the firewall feeds the cluster, bye bye.
 
So this first picture is the plugs that go into the box under the drivers side of the dash. This is the firewall section of the harness off of my 98
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This second picture is the same harness off of the 02 body.
762CC0FA-D11A-4982-A50E-8666E6D2ECFE.jpeg

Obviously the plugs are the same, but I imagine the wires in them are different. Should I be able to just plug the 98 harness into the 02? Or do I absolutely have to pull the dash and swap everything?
 
Maybe the harness on the firewall can stay but the one on the dash has to go. Pull the dash, much easier to see which is which. If the one on the firewall feeds the cluster, bye bye.
Mrblaine, I just wanted to say thank you for your help In this thread. I was hoping I could ask one follow up question. I’ve got my body on and my engine running, and you were definitely right. None of my cluster works. Do I need to swap the entire dash harness out? Like the hvac controls and everything? Cause if so, I’ll have more compatibility issues because of the different years and whatnot. I’m just not sure what to swap and what to leave. Any help would be appreciated here. Thank you.