97 cherokee swap, wiring issues.

[JeepcoMJ]

I'm going to hopefully pick up a totalled 97 cherokee today. it's a 4.0/5 speed (ax15) with np242 and 29 spline 8.25, all power everything.

 

the motor is going into an 89 comanche with a 95 aw4 (have the right flex plate for it) and 95 wiring harness.

 

the 97 interior and harness is going into the 3800.

 

it has one good fender and half a good header panel...I know where another one is with the opposite side in good shape, so I will probably resort to glassing two headers together.

 

 

anyways. I know I've been adament about saying you can't make a 97+ gauge cluster work with an older 4.0.

 

BUT....

 

I had an interesting little idea.

 

the 3800 camaro motor runs on it's own wiring harness. it's using jeep oil pressure and temperature sending units...I'm wondering if I can put the 4.0 wiring harness in and use it's sending units on the 3800. I would run a 4.0 computer and "trick" it into taking the right input parameters for a running at idle 4.0, so basically all the 4.0 computer would be doing is translating inputs to the gauge cluster.

 

 

anyone think it's possible? I know I can change the signal from the 3800's tachometer to match that of a 4.0 fairly easily. the only issue I'm having is what do I do to eliminate fuel delivery systems from the 4.0, and how do I trick the computer into not throwing a CEL when it sees that the tachometer is increasing but it's values from the fake TPS and other fake sensors are not increasing.

 

 

...it's either this, or I just hack everything I don't want that's related to 4.0 from the engine bay harness, and keep only the power supplies to the dash wiring, and all lighting wiring intact in the 4.0 harness. then run autometer gauges in place of the 97 cluster, for which I have an A-pillar pod in order to make them all fit.

[jpdocdave]

why not run an older gauge, that doesn't use inputs from the computer? w/ the 4.0 computer i can't see how you can avoid it seeing improper, or no values for the fuel delivery system. but then again, why are you concerned about check engine light? you don't have emissions to worry about right?

 

so are you just trying to make a late style cluster work in it, and thats all. or is there more to your goal.

[jpdocdave]

when did jeep get the bright idea to make the oil pressure "guage" not really a gauge? i know around that time in tj, the gauge is not a real reading of oil pressure. there were too many idiot customers coming in complaining about the gauge moving so much, so they changed it. its basically an idiot gauge. does not show what pressure is doing. it gives you a middle of the road reading and then will go low and turn the light on with a problem.

 

but i've had some newer xj's where the gauge seems to actually work, cuz i have an idiot customer that doesn't change his oil till his pressure is 10 psi, and light comes on at idle. and after the oil change his pressure is back up to 30. so now that i think of it, that shouldn't be a factor. but it would suck if it was.

[JeepcoMJ]

why not run an older gauge, that doesn't use inputs from the computer? w/ the 4.0 computer i can't see how you can avoid it seeing improper, or no values for the fuel delivery system. but then again, why are you concerned about check engine light? you don't have emissions to worry about right?

 

so are you just trying to make a late style cluster work in it, and thats all. or is there more to your goal.

 

 

ant run the oldergauge cluster with the newer dah..it wouldn't fit even if I wanted to.

 

 

I'm doing a 97 update on the truck. I am keeping the 3800 v6 though...it has more power and torque than a 4.0, and I regularly get 27-31mpg with it when it is running.

 

so, I can't use anything 4.0 related.

 

 

I'm thinking I could have those sections of the computer flashed and removed, so all it does is take the inputs from the sending units.

 

the other option is to just throw it all in like that and not bother faking anything, cut the check engine lite wire out, and hook the 3800's check engine light pinout at the ECU to that light. that's probably my best bet.

 

because the gauges should theoretically work even if the rest of the computer does literally nothing. all I need form it are mph from the electric speedo, oil pressure, volt meter, fuel level, and coolant temp.

[Geonovast]

tach isnt ecu controlled?

[jpdocdave]

ok, so you want the all newest interior, and if your only goal is to make that cluster work, it shouldn't be that hard.

 

i don't know if the computer can be programmed to remove the other inputs, i don't think the dealer would even have the software. some aftermarket company, like the ones that flash computers to run hemis and stuff, but that has to be crazy expensive.

 

the other option is to just throw it all in like that and not bother faking anything, cut the check engine lite wire out, and hook the 3800's check engine light pinout at the ECU to that light. that's probably my best bet.

 

i think thats the way to go. since the 38000 is stand alone. and if the obd system works thats all it would take to make check engine light work, if your concerned about it working.

and just use the 4.0 parts to make the cluster work and thats all. i think thats cooler than mechanical gauges to have the interior functioning in that mj.

[JeepcoMJ]

tach isnt ecu controlled?

 

 

it goes through the ECU yes, but I can adapt my signal from the 3800 to that of the 4.0 and send it through the 4.0 computer to be interpreted.

 

hmm. I may attempt this...get the motor rebuilt, throw it back in with the 97 wiring just layed in the engine bay, and attempt it and see if this works. if it does, great. if not...just get autometer white gauges with a green backlight

[jpdocdave]

tach isnt ecu controlled?

 

ya, but he seems confident that he can use the cam signal from the 3800, and make it work in his cluster. which will be tough cuz i think that was a newer 3.8 w/ 3 coil pack. but it can be done.

[JeepcoMJ]

ok, so you want the all newest interior, and if your only goal is to make that cluster work, it shouldn't be that hard.

 

i don't know if the computer can be programmed to remove the other inputs, i don't think the dealer would even have the software. some aftermarket company, like the ones that flash computers to run hemis and stuff, but that has to be crazy expensive.

 

the other option is to just throw it all in like that and not bother faking anything, cut the check engine lite wire out, and hook the 3800's check engine light pinout at the ECU to that light. that's probably my best bet.

 

i think thats the way to go. since the 38000 is stand alone. and if the obd system works thats all it would take to make check engine light work, if your concerned about it working.

and just use the 4.0 parts to make the cluster work and thats all. i think thats cooler than mechanical gauges to have the interior functioning in that mj.

 

yeah it would be expensive, but I know a couple of guys with tuners that could probably do it for a smaller fee.

 

I think my theory on making the gauges work should work. just trying to think if I'm missing anything in it though.

 

and the aftermarket gauges I'd use would probably be digital or at least electrical....I can't use mechanical tach on the thing, there's no provision for it and I have no intent of relying on mechanical gauges. I trust electrical more because if they fail, I can diagnose it...and also it doesn't have a cable that can kink, get melted by the headers, etc.

[JeepcoMJ]

tach isnt ecu controlled?

 

ya, but he seems confident that he can use the cam signal from the 3800, and make it work in his cluster. which will be tough cuz i think that was a newer 3.8 w/ 3 coil pack. but it can be done.

 

 

lol. it does have 3 coils.

 

but. I already adapted it with a signal modifyer from bakerelectronix...I see no reason why I can't do it likewise to match the 4.0 signal.

[jpdocdave]

ya, by mechanical i meant any aftermarket gauges.

 

it should work, i think the tach is the only hard part, only cuz i've never tried that one before.

i've got a barbaric plan b if thats all that hangs you up, that should make the tach work.

[Sir Sam]

You won't get the "tach signal" to work with the 97+ gauges.

 

the 97 ecu calculates the tach information and broadcasts it on the CCD bus.

 

The only way to possible get it to work is to trick the 97 ecu with the CPS signal, and to my knowledge no one has ever done this before.

 

 

 

Also, congrats on buying a 97+ cherokee, now you can finally see what the interior looks like. This way you won't tell me I'm wrong when you obviously are. :yes:

[jpdocdave]

i didn't think they were using ccd bus, that bus interface crap is a problem.

[JeepcoMJ]

yeah.

 

 

screw it. going custom gauges.

 

sam, I haven't gotten it yet. just talked to the shop where it's at...owner (doctor) wants $1200.

 

I'll be mentioning everything that's wrong with it. I did listen to it and drive it around the parking lot...runs well, drives decent considering how bent the frame is. shifts great. leaky rear main (or at least that's what I'll be telling him...it's probably just the valve cover since the head is nice and oily) and dirty engine. it's an np231 not a 242, chryco 8.25 rear for sure (29 spline).

 

I think I can get him down to $400-$700 considering that it's not repairable. after popping the hood, and looking down @ the frame...it's bent and twisted in front of and behind the steering box....i.e. the frame rail is JUNK and no right-minded body shop would even attempt to fix it.

 

the roof is also rippled in the rear, both bumpers are shot, etc.

 

but...it's worth it for the parts that I want.

[500 MJ]

Best of luck chewing down a doctor for the price Pat... He's probably not really in need of the money right now.

[JeepcoMJ]

Best of luck chewing down a doctor for the price Pat... He's probably not really in need of the money right now.

 

 

no, but he also probably doesn't want/need the cherokee sitting around since it's wrecked.

 

 

let's put it this way...my buddy bought a mercury mountaineer from a doctor in Chicago who decided to "go green" with a hybrid. he thought it was worthless because it only gets 21mpg, so he sold it to my friend chris for $2200. list price was $9300 in poor condition at that time.

 

 

Doctors (or I should say most of them) don't look at reality the same way we do.

 

of course, the reality of the situation is that the xj is NOT worth more than 700 bucks. hopefully his view on reality isn't too screwed up

[jpdocdave]

yeah.

 

 

screw it. going custom gauges.

.

 

giving up so quickly? :rotfl2:

[JeepcoMJ]

yeah.

 

 

screw it. going custom gauges.

.

 

giving up so quickly? :rotfl2:

 

 

well, I KNOW I can make custom gauges work.

 

I THINK I can make most of the factory gauges work.

 

which would you choose...that which you know, or that which you're relatively cerain?

[jpdocdave]

yeah.

 

 

screw it. going custom gauges.

.

 

giving up so quickly? :rotfl2:

 

 

well, I KNOW I can make custom gauges work.

 

I THINK I can make most of the factory gauges work.

 

which would you choose...that which you know, or that which you're relatively cerain?

 

 

6 or so years ago when i was your age? i'd do what i think i could make work cuz others don't think it will :rotfl2:

 

now, i'd save myself the headache and stick with what i know works.

[JeepcoMJ]

6 or so years ago when i was your age? i'd do what i think i could make work cuz others don't think it will :rotfl2:

 

now, i'd save myself the headache and stick with what i know works.

 

 

I lurnt me real quick...this ain't my first rodeo. (I was told the 3800 wouldn't fit. it's cool and all and I definitely like it better than a 4.0...but in retrospect a 4.0 swap would have been easier.

[500 MJ]

Got this thing yet?

[JeepcoMJ]

Got this thing yet?

 

letting him sit on it. he is incredulous about me asking what his bottom line is...seems to think that $1300 invested a YEAR ago makes it worth $1200 still. He's intelligent enough to know that there is value in the parts...but also intelligent enough to know what a junk yard would offer him for it.

 

I asked a junkyard what they'd pay for a jeep in it's shape, they said they can only do $300.

 

 

I'm going to offer $650 after I let him sit on it for a week and then tell him what the junkyard told me they'd pay for it if he says no.

 

 

there are no other jeepers in the area who'd buy it, and save selling it to some idiot who doesn't speak english, he's not gonna sell it...it's not repairable except to make a beater offroad rig.

 

plus...I exhausted my funds. bought another comanche yesterday