97+ interior wiring into 1996

so this post is a little pre-mature since I just pulled the dash last night and haven't gotten the chance to really dissect the wiring, but im posting anyways to get some discussion going that might help me out. Just a little backstory, im swapping the 97+ interior (specifically out of a 98) into my 96 Cherokee sport. The donor 98 had power everything and a few other upgrades that would add a little bit of luxury to my interior. So im swapping everything out, and by everything I mean EVERYTHING, the dash, seats, carpet, trim, door seals, doors (instead of trying to rig up just the inner panels somehow) etc. Before anyone asks, yes im taking pictures and I plan on doing a thorough write-up once I get a little further in. ive read the other write-ups on swapping the dash, center console etc. but nothing seems to address the wiring specifically. Both vehicles were auto's w/ AW4's the 98 was 2wd and my 96 is 4wd but that's it. since their both OBD2 vehicles im hoping this is pretty straight forward.

my question / concern is this, first off, the main harness plug coming in from the firewall is different between the 2 models, my thought is to just go around with a volt meter and map out the plug positions on the entire connector and then cut and splice in the 98 style to the engine wiring harness. my concern here is that the TCU and Airbag module would have to match the 96 style so were there any major differences between the two that would cause me problems? are their any other problems im overlooking here?

secondly, the TCU's themselves are different, ones a green connector off the 96, the other is a purple? (i'll have to double check the connector color when I can). my current transmission has been giving me some problems so I went ahead and grabbed a donor off a 2000, my plan was to swap out whats necessary to bolt it up in place of the current AW4. Should I just use the 98 TCU or do I need to do some more wire work and keep the original in order for it to function right with my ECU?? does anyone know what the differences are for the different model TCU's??

IMO, I would definatley map and splice the harnesses. The blend the the 2 harness together in the manner that fits best. If you run into unmatching plugs and components, err to the side that matches the component you are connecting... At the firewall convert the donor wires to the plug at the wall. It's better to keep the TCU and trans together as a set. That means the TCU from the trans donor would be the one you want. I the choice is between 1996 TCU and 1998 and the WIRES dont match up I would go with the one that matches the harness going to the trans, the 96 TCU. Match wiring based on wire colors and pin number NOT Plug colors. The TCU and airbag modules should be interchangable otherwise.
I wouldn't cut any existing wires on the Jeep except where absolutly nesesary to fit the donor harness or component. if any cutting is required, you should do the cutting and splicing ON the donor harness.

93gc40 said:

IMO, I would definatley map and splice the harnesses. The blend the the 2 harness together in the manner that fits best. If you run into unmatching plugs and components, err to the side that matches the component you are connecting... At the firewall convert the donor wires to the plug at the wall. It's better to keep the TCU and trans together as a set. That means the TCU from the trans donor would be the one you want. I the choice is between 1996 TCU and 1998 and the WIRES dont match up I would go with the one that matches the harness going to the trans, the 96 TCU. Match wiring based on wire colors and pin number NOT Plug colors. The TCU and airbag modules should be interchangable otherwise.
I wouldn't cut any existing wires on the Jeep except where absolutly nesesary to fit the donor harness or component. if any cutting is required, you should do the cutting and splicing ON the donor harness.

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Thanks for the input. I agree that the best piece to cut is the piece most likely to become scrap. as for the TCU's the transmission is off a 2000 model, I have a TCU for the 96 or the 98. I couldn't use the 98 tranny since it was 2wd, but I did save the TCU just in case. Im guessing im going to be spending a while mapping out the whole harness and getting all that figured out.

does anyone have any helpful notes on wiring or diagrams or anything?

I think you need to do some more research before you remove or cut anything. 1996 model year is the transition from OBD-I to OBD-II and Jeep made numerous running changes through both 96 and 97. Early 1996 are more like 95's and later 96's are more like 97's when dealing with engine management/emissions. 1997 was a complete redesign and upgrade of nearly every electrical system and component, and most of the emissions controls. As far as I know, 96 gauges are mechanical, and the 97-01 gauges are run by the PCM, so you would need to swap the entire dashboard wire harnesses, and most or all of the under hood wire harnesses.

Since the wire diagrams in the Factory Service Manual cover several chapters, you will probably need a both a 1996 FSM and a 1998 FSM.

Tim_MN said:

I think you need to do some more research before you remove or cut anything. .

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This wiring project is going to require a lot of research, mapping and planning on my part. im really hoping to keep the engine bay harness the same and just swap in the interior harness.

Tim_MN said:

1996 model year is the transition from OBD-I to OBD-II and Jeep made numerous running changes through both 96 and 97. Early 1996 are more like 95's and later 96's are more like 97's when dealing with engine management/emissions. 1997 was a complete redesign and upgrade of nearly every electrical system and component, and most of the emissions controls. As far as I know, 96 gauges are mechanical, and the 97-01 gauges are run by the PCM, so you would need to swap the entire dashboard wire harnesses, and most or all of the under hood wire harnesses.

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I'm aware of the differences in the 96 year model mine is the early production 96. My brother and I both have / had 96's his was the later year that resembled the 97, we swapped parts on a regular basis. The only major difference (that I knew of, and correct me if I'm wrong) was in the rear axle, the late model had the C8.25 and the early the D44. i'll have to look at my gage cluster since I have both of them out right now. and yes I do plan to swap out the ENTIRE dashboard, wiring harness and all.

Tim_MN said:

Since the wire diagrams in the Factory Service Manual cover several chapters, you will probably need a both a 1996 FSM and a 1998 FSM.

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Not a bad idea on the FSM, it may be a little difficult to scrounge up the right ones however, at least for a reasonable price.

I had a long response typed up and my CPU shit the bed. Long story short. I did a 97+ conversion on a 89 MJ. Use all the donor vehicle wiring. Do not cut and splice harnesses. You will be happier when a gremlin comes up in the wiring down the road.

shelbyluvv said:

I had a long response typed up and my CPU shit the bed. Long story short. I did a 97+ conversion on a 89 MJ. Use all the donor vehicle wiring. Do not cut and splice harnesses. You will be happier when a gremlin comes up in the wiring down the road.

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Problem is that the previous owner says there is an electrical gremlin in the current system.

however...... the gremlin might be in one of the computers or sensors, do you think if I stuck with the same PCU, TCU, and sensors, etc. from the 96 I would be ok using the 98 harness?

Use the 98 harness if you want the gauges to work. If you want to shell out $600+ for aftermarket gauges to mold into a custom dash that is up to you. That is the only way I know of to retain the old wiring with the newer dash. The 97-99 OBD-II system is stupid easy to troubleshoot and fix. You will need all the 98 electronics, TCU, ECU, Air bag module, etc...

The 97+ swap is not for the faint of heart. There are numerous firewall mods that have to be made as well as cutting and welding in the newer dash mounts.

If you go with the newer style doors you will also need to change the striker in the door jamb.

shelbyluvv said:

Use the 98 harness if you want the gauges to work. If you want to shell out $600+ for aftermarket gauges to mold into a custom dash that is up to you. That is the only way I know of to retain the old wiring with the newer dash. The 97-99 OBD-II system is stupid easy to troubleshoot and fix. You will need all the 98 electronics, TCU, ECU, Air bag module, etc...

The 97+ swap is not for the faint of heart. There are numerous firewall mods that have to be made as well as cutting and welding in the newer dash mounts.

If you go with the newer style doors you will also need to change the striker in the door jamb.

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ive been comparing the two while I can. I was really hoping that the 96 would not require all the firewall modifications since its so much closer in year model, I haven't been able to compare too closely just yet but we'll find out soon enough. I did as much research on here as I could before I got started but there isn't much documented on the interior swap & I couldn't find a thing on the 96 specifically.

its looking like im going to need to compare a list of part numbers for the 2 year models for all the electronics & sensors. I have no problem using the ECU out of the 98 since I know the PO just replaced it in an attempt to fix the electrical problem. The airbag module wont be a big deal either since the one on the 96 needs to be replaced anyways. the TCU may be an issue since it was meant for a 2wd AW4 and the only transmission options I have are either my 96 4wd AW4 or a 2000 4wd AW4. and im pretty sure all 3 years had different TCU's.

cherokeeproject said:

Not a bad idea on the FSM, it may be a little difficult to scrounge up the right ones however, at least for a reasonable price.

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$7.95 each at PacificCoastManuals.com

Tim_MN said:

$7.95 each at PacificCoastManuals.com

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Awesome! thanks!

so im still looking into this but it looks like my best approach is to use the complete 98 model harness with the ECU, and TCU. i'll also be sticking with the 2001 model AW4 transmission, i'll just take the 96 transmission out and rebuild it as closely as possible to the 2001 to use as a spare. some of the sensors matched up part numbers between the 96 and 98 so i'll check them with a meter and use the best of the 2. I'll salvage what I can and then replace the rest.

my biggest concern is still using the 2wd wiring harness and 2wd TCU with the 4wd system. I haven't even begun to look into what sensors and electronics are on the NP231 T-case but Im going to need to make it work somehow.

The wiring should be there for the transfer. It will be a dead plug probably taped to the harness. The harnesses are generic and have many unused plugs on them for different versions of XJ models.

The 2WD and 4WD trans use the same wiring. The only wiring on the transfer is for the dash lights. one plug for H/N/4wd and 4WD LOW.

Beleive me, If I can put a fuel injected V8 in a MJ you can pull off swapping a dash, HVAC suit case, trans, fuel tank and wiring harness.

You will also have to modify your tail lights slightly to get them to work.

shelbyluvv said:

The wiring should be there for the transfer. It will be a dead plug probably taped to the harness. The harnesses are generic and have many unused plugs on them for different versions of XJ models.

The 2WD and 4WD trans use the same wiring. The only wiring on the transfer is for the dash lights. one plug for H/N/4wd and 4WD LOW.

Beleive me, If I can put a fuel injected V8 in a MJ you can pull off swapping a dash, HVAC suit case, trans, fuel tank and wiring harness.

You will also have to modify your tail lights slightly to get them to work.

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Thanks for the vote of confidence. the hard part is getting the momentum going and not wanting to just start cutting and splicing wires together to make it work. I have to hold myself back and take the time to do the planning first.

I just really hope that I don't have to chop up the firewall as much as ive seen in some threads, im holding out in hopes that the 96's will bear a little closer resemblance to the 97+'s

It is no more like the 97+ firewall than a 87 is. You can cut the firewall out of the donor and use it as an overlay using the brake booster to locate the patch panel. The HVAC box will need a piece welded in to close the 96 hole up a little. the 97+ HVAC hole is smaller and you will have a major leak if you don't weld it up.

Look this over. These are on MJs but they are the same from the doors forward.

http://comancheclub.com/topic/30671-97-swap-how-to/?hl=conversion