94ZJ 42RE transmission problem

[ROGLSTUBB]

throw out bearing...part 1

I hate automatic transmissions!!! But for the wifes sake I got one in my ZJ. Now here is the problem.

When I left from work yesterday and I put the shifter in drive it felt powerless like it was in third gear. When I put the shifter in 1 I do get first gear. When I put it in 2 I only get second and when it is in drive I only get third and fourth gears.

This according to many is a problem caused usually by the governor pressure soleniod and possibly the governor transducer sensor in the valve body in the transmission. I talked to the dealer and a transmission shop plus did my own research online and found this is more than likely my problem.

My question is has anybody taken there valve body off at home? Is there any special precautions I should be considering? I know about the checkball underneath on the older transmission's is there any on these? Or am I the only one brave/crazy enough to attempt this one myself.

 

[MudderChuck]

Speaking from a position of ignorance, I know absolutly nothing about the 42RE, but having been inside a few close relatives, wouldn´t recommend it for the faint hearted. Wouldn´t even attempt it without a good FSM. And even with the FSM, would be real careful and not count on component locations, wiring and valving to be exactly like, what was in the book.
Besides having transmission fluid dropping in your face for hours, while you try to figure it out.
Electronically controlled on some other transmissions, means the defualt is manual control. Often a power problem to the TCU circuits. For most model transmissions in the FSM, they give the test procedures with the applicable test unit and alternate continuity test procedures. Might be able to nail the problem down before you open it up.
Just my $.02.

 

[ROGLSTUBB]

I so wish is was a simple electrical problem. I read a post on another forum where it was just a fuse. I ran downstairs to my jeep and checked it but to my digust it was not it. I finally found information late last night on how to pull the trouble codes on the TCM. It only had 55 which is end of codes signal so no luck there either. Every post I found there was a problem with two componets mentioned above. There is one other test which involves attaching a pressure guage to the soleniod pressure port. Pressure should be equivilant to vehicle speed. 10 miles per hour per 10PSI and so forth. The soleniods apparently have a tendency to fail and allow pressure while sitting still, which causes the transmission to think it is moving faster and not use the lower gears for overspeed safety protection, Funny thing was that every post had a 94 grand being the one with the problem. But that was the first year they put it a grand. I am ordering the specific book on the transmission to help with the technicals. I was lucky by going to the transmission shop the guy actually had a 42RE apart on a bench and was kind enough to show me the parts I would have to replace.

I dont mind getting a little trans fluid in my hair and on my face. It sure would not be first time.

 

[MudderChuck]

Let us know how it turns out, always looking to learn something new.
Good luck.

 

[ROGLSTUBB]

While I am waiting for the book to arrive I am trying to test the governor pressure solenoid in this thing. I converted an old R12 AC pressure guage to do the job of seeing if the pressure to the governor pressure port is higher than 3 PSI at idle in drive. To my surprise there are three pressure ports on the transmission. So my question is to any of you auto transmission techs is which on is the governor pressure port. There are two on the right side and one on the left almost at the transfer case. I know I could wait for the book but there is no fun it that.

 

[ROGLSTUBB]

well disregard the last post I got the book today and I will test it Friday evening.

 

[ROGLSTUBB]

I dont know if anybody was following this but I figured I would post my results and inform anybody else that looks into this in the future just how simple of a repair this actually turned out to be.

First smart thing I did was to purchase a book specically on my transmission. Automatic transmission service group "ATSG" sells books online on just about any transmission and transaxle out there. They had one just for the 42RE and inside was the complete diagnostics on how to troubleshoot my problem. I was able to figure out that my governer pressure sensor was bad.

The sensor itself was not as bad to get to as I first had anticapated. The transmission shop I had went to told me that I was going to have to remove the whole valve body but in all reality I did not have to. All I had to remove was the governer plate which was 4 11mm head bolts and two torx which were the same size as the filter which you should replace while your under there anyways and the plate came down with full axcess to the sensor and the governor solenoid which are to two most common componets to fail in these transmissions.

So to finallize I am going to say if you run into this or any other problems with this transmission and you can use a voltmeter, pressure guage, and are confident with testing other sensors in the jeep I would say this is something that you can easily do yourself with out having to pay a crapload at a dealer or transmission shop.

BOOK $20 MY COST
SENSOR (old stlye) $132


dealer or shop
Dealer diagnostics $81
New transmission (Autozone) $1500

confindence that the Job was done right by you $priceless

 

[MudderChuck]

Thanx for the follow up and the info. One thing about a problem like you discribed, is chances are you´ll see it again.
This post will be nice to have in the archives, thanx again.

 

[mud4feet]

yj headers!

confindence that the Job was done right by you $priceless

8)

 

[ChuginSudz]

nice follow thru on that problem & thanks for sharing the info with us...