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Transmission intermittently stuck in 2nd gear

WraithKWK

WraithKWK

NAXJA Forum User
Location
Spring Valley, Ca.
89 Jeep Cherokee Limited 4x4
AW4 Trans 242 TCase

Heading back from a weekend camping,
I drove 6 miles down a dirt road then as soon as I hit pavement Bam! Locked in 2nd gear.
Drove it back to my Camp shut it off. Fired it back up to look over the engine, I was thinking it was an engine issue at first cause I lost all power. Turns out It wasn't a loss of power, it was just trying to take off in 2nd gear was all most more than my tired motor could handle. Anyhow I test drove it after finding nothing wrong with the engine and it was fine.

I drove it for a week before it messed up again,
Dropped my daughter off at school and on my way to work Bam! Stuck in 2nd. With a Mighty top speed of 45mph at 3 grand I limped home. The next day I dropped it off at the tranny shop to get it tested and they couldn't get it to mess up.

Any Idea's?
I've been googling and searching all I can come up with is possibly a silenoid.
 
WraithKWK said:
89 Jeep Cherokee Limited 4x4
AW4 Trans 242 TCase

Heading back from a weekend camping,
I drove 6 miles down a dirt road then as soon as I hit pavement Bam! Locked in 2nd gear.
Drove it back to my Camp shut it off. Fired it back up to look over the engine, I was thinking it was an engine issue at first cause I lost all power. Turns out It wasn't a loss of power, it was just trying to take off in 2nd gear was all most more than my tired motor could handle. Anyhow I test drove it after finding nothing wrong with the engine and it was fine.

I drove it for a week before it messed up again,
Dropped my daughter off at school and on my way to work Bam! Stuck in 2nd. With a Mighty top speed of 45mph at 3 grand I limped home. The next day I dropped it off at the tranny shop to get it tested and they couldn't get it to mess up.

Any Idea's?
I've been googling and searching all I can come up with is possibly a silenoid.
Click to expand...


Sure it's 2 and not 4? Up under the passenger side dash is the Trans Control Unit. AKA TCU. It has an inline fuse to it wrapped in yellow tape. If that fuse is blown, or it's connections corroded, you will experience the same symptoms you describe.
 
check fuses. clean connections to TCU under the dash and the ones under the hood. test your solenoids with a multi meter to make sure they are working right. My gut filling is if the fuse is bad or connections are corroded thatll do it. if not, Id test the solenoids.
 
Sorry for the late reply its been a busy week, I checked the 7.5 amp fuse labeled Trans on the fuse block drivers side. It appeared to be fine. I'm not sure where the TCU is exactly but there was a 10 amp fuse dangling from the wires going to what I believe is the TCU Passenger side center attached to the bottom dash panel
 
The TCU gets it's gear selection input from a switch on the passenger side of the transmission. It gets dirty and causes interesting functioning, like acting like you are in 1-2 instead of 3 or D.

There is a procedure for cleaning it (Write-up) but I can't seem to remember where. Something to think about.
 
WraithKWK said:
Sorry for the late reply its been a busy week, I checked the 7.5 amp fuse labeled Trans on the fuse block drivers side. It appeared to be fine. I'm not sure where the TCU is exactly but there was a 10 amp fuse dangling from the wires going to what I believe is the TCU Passenger side center attached to the bottom dash panel
Click to expand...


Within 6" of that fuse, bolted to the underdash panel.

Along with re-doing the NSS, think about doing this:

Cruiser’s Trans Plug Refreshing

Over near the transmission dipstick tube are 2 rather large connectors. One is black and the other gray. These 2 connectors carry all the info between TPS, TCU, NSS, speed sensor, and transmission solenoids.
Unplug each one, visually inspect for corrosion or bent pins, spray them out with electrical contact cleaner and plug them back in.

Additionally, if your Jeep is an 87 to 90 Renix, it’s always a good idea to reach up under the glovebox area and unplug the connector to the TCU and spray it out along with the receptacle of the TCU. While you’re there, find the fuse right in that area for the TCU. Remove it and spray out it’s receptacle and clean any corrosion from the fuse.
Revised 9-10-2012
 
Thanks Guys,
I have a bunch of Cruisers Guides saved on PDF. I'll have to add that one to my list.
 
Note from DJ
More information on Transmission Control Units Location
http://www.naxja.org/forum/showthread.php?t=1045326&page=2
Post #18 by MoFO
It is under the glove compartment on the passenger side. There are 2 screws that go through the lower edge of the dash and into the TCU mounting bracket. The TCU is inside a flat sheet metal can about 4" x 6" x 1" thick. The mounting screws are not needed for a TCU ground. You can pull them out and let it hang from the harness while you troubleshoot.

Here is a good post on diagnostic
Please look over the complete # 2 post by coppertop71
AW4 Question
http://www.jeepforum.com/forum/f11/aw4-question-254062/
 
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