[gregmondro]

Ok guys.

originally I thought my 94 ZJ 4.0l was sending the transmission into Limp Mode due to the TCU (transmission computer). Now I'm thinking that it is going into limp mode because it is actually overheating. I've noticed it a lot more now that the weather here has reached the 90+ degree mark. It usually seems to do it while going up hills and while the weather is hot.

The Jeep has the tow package with the transmission cooler if that matters any.

what can I check to see why the transmission is overheating?

you'd think it wouldn't over heat even without a transmission cooler like a lot of ZJ's come (come without tranny coolers).

i'm stumped.


there are no codes saying that anything is wrong when I do the key sequence thing on the jeep on the transmission OD display or the check engine display.

 

[Broder1020]

Have you checked the fluid yet? That's the first thing I would do. When mine gets even a 1/2 quart low it acts crazy. Ever changed filter, flush and fill, etc?

 

[gregmondro]

sorry, should have noted in the original post.

the transmission is new, it doesn't even have 10k miles on it yet. It was professionally installed by the Jeep dealership (i bought my Jeep and the transmission went out a week later so it was replaced under the warranty I opted for).

so.

transmission is new
fluid is at the correct level, still red, doesn't smell burnt.

btw, the Jeep has 130k miles on it now, so lets say the transmission was replaced at around 125k

 

[gregmondro]

bump..

 

[Bulldog 6]

What kind of warranty did you get with the tranny? They are usually 12K/12 months or something like that.

Did they replace the cooler when they replaced the tranny. My bet is the tranny cooler is phucked, hence the reason for your overheating. I have also heard there is a checkvalve in the tranny cooler lines that fails and quits flowing through.

 

[MUDDTRACKS]

tranny cooler or radiator clogged

 

[gregmondro]

should this make a difference?

some ZJ's come WITHOUT a tranny cooler to begin with, and im sure they don't overheat in normal driving conditions.

If it is something else, I don't wanna put a bigger tranny cooler and basically just put a bandaid over a bigger problem, ya know?

 

[Cue-Ball]

Since they recently installed the tranny take it back to them and tell them you're having issues.

My guess is that the cooler is plugged up or something like that.

(maybe you need synthetic ATF like Amsoil, it does reduce the temps inside the tranny, I just happen to be an Amsoil dealer :lol: )

Dirk

 

[gregmondro]

lol, yeahk I was thinking of doing that.

problem is, the new tranny was fixed under a 3rd party warranty from the dealer I bought my Jeep through (a used cars place).

so i'm not sure if there is a warranty on the new transmission :sad:

 

[Lloyd]

I've never seen an automatic transmission without a cooler.. usually built into the radiator. Many have a remote cooler as well.

I suggest you change the tranny fluid. Do a complete change. drop the pan, change the filter, put pan back on, fill with 4 or 5 quarts. (till full on dipstick). Then disconnect return line from radiator, put a hose on end and run it into a big pan. start engine and run a quart into pan, shut off engine fill up tranny again, start engine, another quart, until you get new clean fluid coming out of line.

Now you have "Changed" the tranny fluid. You have flushed all the fluid out of torque converter lines to radiator and radiator(s).

If radiator is plugged, fluid won't run through the line like it should. At an idle tranny should pump a quart in way less then a minute.

Good Luck!

 

[Bulldog 6]

Take it back to the car lot you bought it from. Find out if they will help you, find out where the trans was replaced at. Talk to that place and find out what warranty you have from them.

Like I said before and so have others, the cooler is probably plugged up. It is 11 years old, stuff wears out. Could be the inline check valve for the cooler lines.

 

[yardape52]

I second or third taking it back. At this point you're shooting bullets in the air.

 

[gregmondro]

i'll just probably replace the transmisson cooler.

I know where all the work was done, but the transmission cooler wasn't replaced.

It will NOT be under warranty, but no biggie :shrug:

if that doesn't fix it, i'm thinking the TCM.

 

[bambam95zj]

Is it always in limp mode or are you saying that it is fine until you get hot? If its always in default then i would look at the TCM ... otherwise look elsewhere.


If you suspect that the TCM is the culprit have the dealer run a DRB scan on it... it can pick up faults (see if the TCM is alive)and send you in a good direction.

I had to replace the governor solenoid on mine(among other things).

 

[gregmondro]

seems only after it gets ran for a while.

UPDATE:
went and checked the codes on the transmission again with the key trick.

The OD light flashed 15 times, stopped, flashed 15 times, etc. It did this until I took out the key.

I'm guessing this would just mean code

15 Throttle position sensor input

what do you guys think I should do to go about checking on this?

I'm going off of these codes that someone posted on another board.

Tranny Codes for 1994 Quadratrac

11 Engine RPM input
12 Output shaft sensor input
13 Vehicle speed input
14 Governor pressure sensor input
15 Throttle position sensor input
16 Transmission fluid temperature input
17 Overdrive override (control) switch input
18 System voltage
19 Internal fault in module
21 Governor pressure solenoid output
22 Overdrive solenoid output
23 Converter clutch solenoid output
24 Overdrive override (control switch) lamp output
25 Internal fault in module
26 Governor pressure sensor offset drift
55 End of code transmission

 

[DJJordache]

tranny cooler or radiator clogged

x2 mine fried because of this! I know for sure b/c I have a temp gauge in the line and it read no change from cold because there was NO FLOW... So I had it rebuilt and it went into limp mode again, so I bypassed the rad and aux cooler with a ghetto one and I had flow and the temp gauge read right again...

I cleaned out the radiator cooler and replaced the aux one. it might be something to try...