XJ_will

I think after reading what a bad speed sensor causes I.e poor fuel mileage erratic shift points and some other stuff that directly relates to the same problem.

XJ_will

im replacing mine tomorrow.

frhrwa

not really, according to the dealership, 1996 is the one year that is specific.. most of the other years have a range of parts to use, but '96 uses a '96 part only.. the ECU is specific for one.. mine has 3 plugs.. when I replaced the TCU, I had to buy one for a '96 (of course it didn't fix the damn problem).. by the way, is this a jeep flu virus? seems to be going around a lot..

lomaxanderson4

Mine has been acting funny..

wouldn't shift to 3rd till 2500 rpm ... warm up and shifted fine ...

now this morning it seamed to bog down and wouldn't take more throttle in second hung around 2000 rpm... you could ease it up to 50 mph ... but didn't want to rev up right...

When I tried to downshift it would pick up the rpm but didnt pull the truck...
its a 95 2wd Cherokee sport 4.0

I too am from a gm history but I love this old Jeep ... and it is teaching me all kinds of things...

William Smith

Hello Folks,

I am receiving responses or updates to this thread that talks about a shifting issue and the words like TCU, fuse, sensor and servos come up quite a bit.

Another word we should point out is speedo cable. The reason is on some models of older jeeps like my 1987 Jeep Cherokee with select trac they used a "speedo" cable about 1 foot long hard to get at connects from the transmission to some kind of electronic device which works with the TCU and on board computer.

Let me make myself clear regarding my solution to a shifting issue experienced a couple years ago that has now be RESOLVED.

I spent quite a bit of time troubleshooting my problem and wanted to give back by providing folks some of the possible symtoms that tricked me into believing I should spend money on everything first before actually discovering there was a speedo cable I never knew about on my transmission that was the culprit all the time. " If you have this on your transmission find one at a wreaking yard if you have time or purchase one on the web" and give it a try.

Symtoms:

When stopped and taking off at a light vehicle would not shift out of first gear automatically

Transmission at any speed, one day I'd be driving 20 miles an hour and a slight or drastic slip of the transmission would occur, maybe a week later it would happen again at 50 mile an hour. Point is, it was intermitent.

Actions taken by my mechanic and I over a 2 year time frame:

Transmission flush complete using a flush machine not removing transmission pan. This means the metal filter inside the transmission was not imspected at this time.

Check all wiring connectors under the engine and at the TCU under the dash.

I put heat wrap around sensitive wire points that resided close to manifold or engine where gets hot the most.

Cut out TPS from wiring harness because we thought the connector was bad causing incorrect readings by the main computer. This was a tech note from as far back as 1987 and 1988. This corrected the issue I told you all about that I had when starting with high idle revs. My mechnanic and I gave cutting out the TPS connection and directly soldering the wires with heat wrap would be a true connection. Process of elimination.

Next we examined the servos removed the trans pan and I said while you have it apart lets just replace them all. I got all my parts at cost. So why not.

Next we removed the TCU replaced it with one my mechanic had. Drove for a day and it didn't fix the problem. We put my originial one back in.

Finally after 2 years and all this stuff above ..... speedo cable one foot long replaced it and hurray no more problems. Been driving now since early 2010 or late 2009 , can't remember with NO Problems automatic shifting.

NOTE --- I only said to remove the fuse from under the dash where it lives by the TCU in an emergency. If you get stuck out on the road removing the fuse allows you to manually shift with no harm to your transmission.

Hope this all helps

Cheers

cruiser54

So what was wrong with the cable?

XJ_will

ok update mine was doing the same thing and I changed the cap and rotor, cleaned the crap out of this iacv which was black now super shiny and my jeep has shifted on point everytime for the last 3 days .... Weird but I'm ok with it.

frhrwa

I agree, what was wrong with the cable?


my tcu fuse is located under the hood, passenger side fender well in a fuse box.. 10@ fuse, real small..

cruiser54

He's got an 87 with the fuse on the drivers side under the dash. Only one fusebox.

frhrwa

where exactly is this speedo cable? can you reach it when you crawl under the jeep? or does it have to be on a lift"?

89cherokee2gtmudy

Back when I had my 89 I had to drive home towing a small trailer with the 10 amp fuse removed that is located on the passenger side along the tcu harness. It shifted fine till I put that stupid trailer behind it. I have already sold the 89 but is it normal for the trans to shift towing a trailer that is within the weight limits. It did have factory trailer hitch with the cooler. It just couldn't make up its mind to which gear it should be at in low speeds 25-45

cruiser54

Coulda been the TPS had a bad spot up in the area of larger throttle opening.

frhrwa

1996 Cherokee Sport 4.0L perfect condition except shifts weird and I cannot find the F*(^&^G problem and I'm damn tired of looking for it!! FOR SALE