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Overdrive Issue AW4

F

fiveltretr

NAXJA Forum User
Location
MD
Ok, so tonight i was driving home and my trans tried to downshift, then was ok until overdrive. It kicked out of overdrive on me. Drove it into parking lot, turned it off, started it again, everything was fine for a while, then it kicked out of overdrive again. If I drop it down into 3rd the torque converter locks up, shift into overdrive, and it wont lock up. came to stop light turned jeep off and started it again, had no problems from there to the house, 6mi. What is going on? I believe it is a sensor issue, like TPS, or maybe NSS? I dont know, I got a smoking deal on this jeep and would like to not spend the money on a transmission. Please help!!
 
fiveltretr said:
I believe it is a sensor issue, like TPS, or maybe NSS?
Click to expand...

What year, engine, etc we talking about? Newer models will often throw a code and tell you if it think the NSS (aka PRNDL switch) is reading wrong. TPS is the usual culprit for odd shifting like this. If you have an analog meter, I'd start be testing it.
 
Step one:

Post up the year/engine/etc.--this should be done in every thread you start.

Step two:

Check the fluid level and condition: color red, does it smell burnt?

Step three:

Determine if the problem is hydraulic/mechanical or electric in nature. You can do this by unplugging the TCU, transmission control module, or by removing the 10 amp fuse in the yellow wire running into the TCU. The TCU is under the dash, either on the passenger's side or the driver's side--depending on the YEAR--see, I told you. With the TCU unplugged you can drive shifting manually. You should get 1st in 1-2; 3rd in 3; 4th in D; reverse, neutral, park. If you don't get those, then you have a mechanical/hydraulic issue.

Post back with what you find. Oh, and include the YEAR too.
 
joe_peters said:
Step three:

Determine if the problem is hydraulic/mechanical or electric in nature. You can do this by unplugging the TCU, transmission control module, or by removing the 10 amp fuse in the yellow wire running into the TCU. The TCU is under the dash, either on the passenger's side or the driver's side--depending on the YEAR--see, I told you. With the TCU unplugged you can drive shifting manually. You should get 1st in 1-2; 3rd in 3; 4th in D; reverse, neutral, park. If you don't get those, then you have a mechanical/hydraulic issue.
Click to expand...

My AW4 in my 97' is doing the same thing. I got a code from the jeep it read "12-45-55" and when i went to have the code read at autozone it came back as "transmission control system malfunction".

Mr. Joe Peters what would you suggest I do?
 
Twisted_Dakota said:
My AW4 in my 97' is doing the same thing. I got a code from the jeep it read "12-45-55" and when i went to have the code read at autozone it came back as "transmission control system malfunction".

Mr. Joe Peters what would you suggest I do?
Click to expand...

Check the 10 amp inline fuse first.
 
On your 97 I believe it is the driver's side between the steering column and the air box.
 
Twisted_Dakota said:
My AW4 in my 97' is doing the same thing. I got a code from the jeep it read "12-45-55" and when i went to have the code read at autozone it came back as "transmission control system malfunction".
Click to expand...

It is always helpful to have the exact code number posted here. With codes, the devil is in the details.

Another good thing to try is to GOOGLE the code(s) + JEEP and see what hits you get for others that have had the same issue.
 
Ok, sorry, I thought that I had filled out my signature on this board. It is a 96 cherokee country with the 4.0. I believe that it is electrical, but I could be mistaken. Where Is the tcu on a 96 I will start there, but like I said this is intermittent
 
TCU on a 96 is under the lower portion of the dashboard on the passenger side.
 
I did all of this a few weeks ago and cleaned my NSS and replaced the TPS and adjusted the TV Cable. Ended up one of my shift solenoids was actually cracked at the top of the valve and instead of all the fluid going thru the valve body it was spraying back down into the pan so sometimes it would shift right..and sometimes it wouldnt.
 
Have an update. There is an erractic "downshift", engine rpms go way up then come back down, then seems to default to 3rd gear, no cel, no codes with my code reader. It is odd, because with out doing anything about 20min of driving later, it went back into overdrive. Does this sound like a TPS issue?
 
I had the erratic downshift when my NSS went out on my 1998 XJ. It didn't throw a code. Cleaned the NSS and the problem went away.
 
fiveltretr said:
Have an update. There is an erractic "downshift", engine rpms go way up then come back down, then seems to default to 3rd gear, no cel, no codes with my code reader. It is odd, because with out doing anything about 20min of driving later, it went back into overdrive. Does this sound like a TPS issue?
Click to expand...
What speed does this occur at? If it is up near highway speed it may be your torque converter unlocking for a second. Check the solenoids (resistance) and the switch on your brake pedal if this description fits. Also check the NSS like the_weirdo suggested.
 
my 2001 started doing this today. we got a lotttt of rain (nashville, tn) and it didn't start doing it until i had to cross a couple high water spots. suggestions on where to start? could water have gotten into the NSS?
 
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