1993 3.8 tranny not staying in 4th

[guido0136]

Thanks again for all your help.

The TCC switch I installed only dis-connects and re-connects the D (tan and black) connector, but I read in another thread that both the D and A connectors should be dis-connected to stop the TCC.
Now when I have the D connector dis-engaged while driving after 15-20 seconds 4th gear is lost. If I also dis-connect connector A will this allow me to not have TCC engage but keep 4th???

Please let this be the answer....

[LMP]

I will take good notice of tranniman advise about oil fill level.
About TCC solenoid disconnect, disconnecting A OR D OR (A and D) is same. www.avigex.ca/xport/transaxle.jpg
THe fact it removes 4th was not mentioned by others who used this means to get rid of TCC shudder...their threads are like 2 year old...they had indicated all was fine..so I cannot confirm nor deny it is an unavoidable consequence but if it is then it would come from the PCM firmware....
I will investigate that with mine next spring...
....however, in the mean time, I'm just thinking the computer checks the electrical status of inputs/outputs and the solenoid not being there, the electrical condition at the PCM contact can be seen as an error (normally reported as QUAD DRIVER A error, in this case DTC26 www.avigex.ca/xport/dtc26.jpg) in addition to the obvious "TCC slippage" that will be observed. So, since you have already done the test, I'd in fact disconnect A and DD...and install an equivalent electrical load between the A and D--wire side of connector - , in this case, a resistor or other load having a resistance between 30 ohms and 50 ohms (a resistor would have to be 10W rating). IN this case the computer will think the solenoid is still connected, and it might change the way the computer reacts, depending on firmware.

[guido0136]

An interesting theory. I'll see if my brother-in-law (a mechanic) can help me with this. I'll also go out a buy more tranny fluid and overfill 1 qt just to see what happens.

LMP - people have said it before, but, you are a wealth of knowledge -THANK YOU.

[guido0136]

UPDATE - Winter is here in full force with temps around -10 to -20 Celuis. Since the cold snap has hit, my tranny is running PERFECTLY. So this issue appears to be related to heat.

Would a Tranny rad help? I've seen these on my Brother-in-laws stock race car. They mount just in front of the regular rad.

Has any one had this done on their 4T60E tranny?

Thanks,

[wagonman76]

I had this exact same problem on my 92 Trans Sport with 4T60E. I had problems with TCC shudder, and the TCC and OD dropping out after sitting in traffic, or pulling a trailer. Directly related to heat. Wouldnt go back into TCC or OD till I restarted. First I did a fluid and filter change and no difference. I took resistance readings and most solenoids were just a hint over spec, but one was like 118k ohms. So I bought a solenoid kit and tore into the side pan. Just for kicks I measured the solenoids themselves, and every one was perfect. So I suspected the harness. I cleaned it really good. Also the solenoid connectors seem like a really hokey design. It seems they cant get tight no matter what, and it looks like they can heat up and expand and lose connection. I tightened them the best I could till I got good readings outside the trans. The problem is solved for the most part now. Its like 90% better than it was. No more shudder. But when pulling a heavy trailer up big hills, it heats up just enough to kick out OD and the TCC once in a while. When I get a chance to go in the side pan again, Im going to cut out those stupid connectors and solder and heat shrink the connections. Till then I can deal with it now when I tow the camper. I have to adjust the throttle so if it heats up on a long grade, I cant let off enough to where it would let it go into TCC mode till it cools below 3/8 on the gauge. I dont use OD when towing and I use a big tranny cooler, but I want the TCC. Its the condition when it TRIES to engage the TCC, but cant because of heat expanded breaks in the damn connectors, is when it screws up and locks out OD and the TCC. Before, the problem was almost all the time and getting worse and happened even without towing, and even at 1/4 on the temp gauge. Oh and when I first tested it, I took it out to the big hills with the camper and it got to 1/2 on the temp gauge and didnt act up. Now its at 3/8 on the gauge when I gotta watch it. The connectors just keep loosening from heat and vibration. I hope to solve the problem for good with soldering the connections this summer. Its a good strong tranny, just has a chintsy control system.

[guido0136]

another interesting idea. Can you give me a more precise location of this harness so I can give this a try.

Thanks,

[wagonman76]

When measuring the ohms and got the bad readings, I measured it at the electrical connector at the front of the transmission. I did it several times to make sure I was getting a good connection with my tester.

The problem harness is inside the transmission. It goes from that plug to the solenoids. Each solenoid has a connector and these connectors are just a really bad design.

To get to this harness, you have to remove the side pan of the transmission. So you have to undo the stabilizer bar, undo the balljoint, remove the axle, undo the tranny mounts, undo the cradle, and lower both the tranny and cradle enough to get the side pan cover off. Quite a job.

[guido0136]

wow; that was more than I hoped for. I was guessing it was somewhere in the engine compartment.... Oh well...

[wagonman76]

Has the resistance been tested at the tranny connector? Thats the first place Id check, like I did with mine. Since theres also a chance it could be something in the wiring between the tranny and the computer. I know of a guy who had a problem there.

My service manual is at home, so I dont know off hand which terminals to test and what ohms to expect. Thats where I got readings that were out of spec, but after removing the side pan, the solenoids themselves had readings that were fine.

I know, its a lot of work, and Im kicking myself now for not just cutting out the connectors and soldering and heat shrinking them right then and there.

[m-sanborn]

Originally Posted by trannyman52

I won't tell you this will solve your problem,,,,but ,,,this trans has issues with fluid levels,,,which may cause similar problems....Over-fill trans about one inch above full {little over one quart}...this will not blow seals out or crap like that!!!! 4t60,,,,4t60-e should ALL be over-filled

Overfilling the tranny by a quart? Why? What does this do? Incorrect dipstick or something?