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Help, auto trans seemsto be stuck in overdrive

B

B.Styles

NAXJA Forum User
Location
South Jersey
96 cherokee 4.0 auto (aw4)... Truck drove perfect and I've never had a problem
with the trans. Now suddenly far from home I started it up to drive back to my
house and it seems to be stuck in over drive. Or maybe the torque converter is
stuck locked. Any help would be awesome. I even tried another TCU out of
exactly the same truck w/ no success. Please help, and sorry if this post weird.
I'm using my blackberry on the side of the road.

P.S. Where is the torque converter solenoid plug located so I can try to unplug it.

Thank you all who can help.
Bob
 
I think all of the solenoids are operated through the same connector.

Have you tried unplugging the TCU and shifting manually? If it will shift correctly manually then your problem is electrical and just leave the TCU unplugged until you have time/place to work on it.
 
So the truck drives fine shifting it manualy with the tcu unpluged. But, it won't start without
it pluged in. Are there anyside affects to the truck running w/out the tcu pluged in for now.
Also, do you think my problem is the tcu or something else? I understand its near impossible
to diagnose vehicle problems w/out seeing the vehicle but I'm just scared its more than the
Tcu and looking for some assistance.

Thanks again,
Bob
 
Well, the problem is not mechanical, and that is good news.

The TCU has it's own in-line fuse, maybe that is why neither TCU works. For sure it has to be electrical, either power/wiring/TCU (probably not)/solenoid(s).

There is zero problem with driving without the TCU plugged in, other than lower mpg.
 
And you only have 3 gears with it unplugged, and no TC lock.
 
A 1996 doesn't have the inline fuse. That was only the early non-HO Jeeps. You do need to start by verifying that you have power to the TCU. The two wires should be yellow and red as I recall.
 
ok i know this is a really old thread but oh well. i have the same year and trans jeep 1996 xj aw4. im having the same problem as him and i just check the tcu and those yellow and red wires are both getting about 9 volts. i changed out the trans soleniods about a year or 2 ago when my xj wouldnt shift out of first gear. i think the OD problem came on about the same time. how can i check if i installed the OD soleniod incorrect without dropping the pan?
 
latenights said:
ok i know this is a really old thread but oh well. i have the same year and trans jeep 1996 xj aw4. im having the same problem as him and i just check the tcu and those yellow and red wires are both getting about 9 volts. i changed out the trans soleniods about a year or 2 ago when my xj wouldnt shift out of first gear. i think the OD problem came on about the same time. how can i check if i installed the OD soleniod incorrect without dropping the pan?
Click to expand...

Start by doing the checks here http://www.transonline.com/transdigest/magazines/1997-10/Shift%20Pointers/index.html. You can ignore the D1 and D3 pins for a 1996, and I think the D2 voltages will be opposite what the chart says. That 9-volts supply is quite suspect, btw. Is that 9-volts to the body ground or to pin D7?

There are two shift solenoids which determine 1st-4th gear, and the third one locks up the torque converter (some mistakenly call this overdrive).
If measuring pin C14 to ground gives you 11-15 ohms then it's a good bet the 3rd solenoid is installed correctly.

Can you clarify what your symptoms are? Is it not locking up the torque converter (possibly bad brake sensor), starting out in 4th gear (likely no power to TCU), or what?
 
ok thanks i will check this in about an hour right now im onthe hunt for a new tcase also. i checked the power to the tcu again and i got 13.5 volts which sounds alot better then the 9 volts i check before. i think i had a bad ground the first time i checked that and that was a ground to the body, not the d7 pin
 
I bought a 96 Cherokee that is having similar issues. First and third gears do not work and reverse is not operational either. Is there a solenoid for reverse as well? Does anyone have a link to a diagram for the transmission?
 
It's me said:
I bought a 96 Cherokee that is having similar issues. First and third gears do not work and reverse is not operational either. Is there a solenoid for reverse as well? Does anyone have a link to a diagram for the transmission?
Click to expand...

Nope, no solenoid for reverse. I'm pretty sure you have a mechanical problem.
 
Check fluid level and condition. Check shift linkage, and also test solenoid operation.
 
So while in neutral and reverse my vehicle is actually in 4th or overdrive. When you get the Rpms up it will pull forward. I talked with a transmission guy that sated he thinks a valve is stuck open thus causing the vehicle to stay in drive. Does this make sense to anyone or has anyone experienced this problem?
 
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