96 to 95 engine harness and computer swap. problems!!!!

[oops777]

i have a 95 xj and changed out the harness and computer for a 96 and now it will not drive well in drive. I can manually shift but no drive. feels like there's a brake on and will barely move. please help going crazy

 

[souske]

you switched the entire harness? there were lots of weird changes for the 96 year
did you use the in tank fuel pressure regulator?

 

[McQue]

Disconnect/unplug the Transmission Control Unit. Then try driving it. Without the TCU connected, you will have to shift manually through the gears. Let us know how the Jeep runs that way. If the TCU is bad, or the 96 TCU wiring harness section is bad or incompatible with the 95 TCU, the results you get from this test drive may help us isolate the problem. Report back with your results in detail.

 

[Tim_MN]

1995 is OBD-I and 1996 is OBD-II. It is not surprising that it will not run right with the wrong computer installed.

Why the switch ?

 

[oops777]

ok just took it for a drive. it runs ok, seems like a lose of power in third and drive. I feel it shit in every gear.

no i only took the harness and computer.

 

[oops777]

when i bought the jeep some one had hacked the existing harness all to shreds and started to give me problems. not being a wire kind of guy i wanted to start fresh. i found this harness cheep so i grabbed it.

 

[souske]

so it is trans related?

I swapped a 96 system from headlamp to taillamp,, but i have an Ax15, so i am no help with the auto stuff.

Did you try mc que's suggestion of driving it without the tcu unplugged?

 

[oops777]

ya i drove it unplugged and it drove fine with me shifting it.

 

[McQue]

When I search part numbers at Rockauto.com, it shows that the TCU part number changes in 1996. I don't have access to a FSM for 1995 or 1996, but when I compared the electrical schematic from a 1994 FSM ( I assume it would be the same as a 1995) to a 1997 FSM ( should be very similar to a 1996) it shows the TCU wiring to be VERY different. Even the range sensor (PRNDL) circuit that ties into the tranny shift solenoid circuit is different.
So, don't know if the 96 harness you installed included the wiring for the TCU but if it did, it looks like you will have to change the TCU to a 96 TCU as well as other wiring related to the tranny and tranny sensors, and shifter. You need to get some advice from someone who knows all the differences in the tranny circuit between those 2 years.

 

[oops777]

man that sucks. anyone know any tranny circuits

 

[Tim_MN]

The logical solution is to use a 1995 computer and wire harness in your 1995 Cherokee. Attempting to update an OBD-I system to OBD-II is not a plug and play conversion (as you have already experienced).

Simply use the correct parts, and it should run and shift correctly.

If you do not understand what OBD-I or OBD-II is, and the differences between them, you need to do more research.

 

[oops777]

Tim_mn thanks for that great advise. some times less is more. in my case the harness is no longer made and my local dealership can't track one down. i have to have one that is specific to my vin it being a half year and the one i need is no more. the research i have done to find one, no one can tell me if its for my vin. i found this 96 harness cheap enough to try to get it to work and was asking around if anyone has done it or anything close to. so logically i came here where there is an abundance of knowledge. that being said i knew i would have to sift thru the annoying remarks that are unwarranted.

 

[Tim_MN]

1996 is the half year bastard Cherokee.

1994 and older would be a better donor choice, and the computer/wire harness will have a greater chance of being compatible as it is also OBD-I.

What's the point of attempting something that simply creates more issues than it solves ?

Cherokees are common as dirt in the junkyards, and finding parts can't be that difficult.

 

[souske]

Nothing wrong with the 96, you just need to use 96 parts.
why not try a proper 96 tcu