Did I fry it? TCU

XJ4PLAY · Mar 4, 2005

First off I blew it now I pay the price.
I had a switch hooked up to a Compu Shift, this device is supposed to do what has been done here by others, keep the vehicle from shifting from 1st to 2nd.
I got the wires mixed up and now it will only shift through the gears manually. I figure I fried something in the TCU. Whatever gear I have the shifter in is where the trans. stays.
Any suggestions other than buy a new TCU?
Diagnosis, fixes, tests, etc. will be appreciated.
This is my daily driver, so Keeping the vehicle down for a while is not a convenience.

Thank you,

Dunce.

RobertF · Mar 4, 2005

First off, what year is it?
Second, check the fuse in the yellow wire near the TCU, this is it's power source.
If you remove power to the TCU all you have is manual shift as you have described.

XJ4PLAY · Mar 4, 2005

RobertF said:
First off, what year is it?

Duh, that would help. Got a ;ittle flustered doing someting dumb.

It is a 1996 Cherokee, 4.0L, 231.

Thank you I will check the fuse.

MrShoeBoy · Mar 4, 2005

If its really fried, I have the TCU from my 91 XJ for sale. PM for details if intrested.

AARON

XJ4PLAY · Mar 4, 2005

MrShoeBoy said:
If its really fried, I have the TCU from my 91 XJ for sale. PM for details if intrested.

AARON

I will let you know.
Are you sure it is interchangeable?

jdougn · Mar 4, 2005

RobertF said:
If you remove power to the TCU all you have is manual shift as you have described.

Robert, does this work on a '98 XJ w/automatic? I could see this being handy for wheelin' since it'd keep the tranny from kicking from 1st into 2nd all the time. What are your suggestions on this? Thanks

JEONLYEP · Mar 4, 2005

I blew a fuse under the hood on my 91 and it was just as you said, a manual automatic. It was a mini blade inside the black box behind the battery, (if yours is the same as mine)

hope that you didn't fry is, doubt that you did. That's why the fuses are there.

Daryl

XJ4PLAY · Mar 4, 2005

Well, much to my relief, it appears as though it was/is the fuse in the Power Distribution Center under the hood.
I did not have a spare, so I "borrowed" one from the wife's car, for the cruise control which she does not use. I gave it a quick try and it seems to shift okay.

Thanks everyone for the quick responses.

XJ4PLAY · Mar 4, 2005

tsgolo said:
Robert, does this work on a '98 XJ w/automatic? I could see this being handy for wheelin' since it'd keep the tranny from kicking from 1st into 2nd all the time. What are your suggestions on this? Thanks

FYI,

There are many threads on how to do this as well as the device I have, Compu-Shift, that will do this.

Gojeep · Mar 4, 2005

The mod is to stop 1st being selected when you want to stay in second not the other way around. The compu-shift is a rip off for what you can do for the cost of a single switch and a couple of diodes.
See my writeup on it.
www.go.jeep-xj.info

Did I fry it? TCU

XJ4PLAY

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