So just when I was enjoying a nice drive on the highway in the warm weather on the weekend i notice that my tranny (rebuilt about a 1.5 years ago, destroyed diff. bearing.) was in third at 120 km/h. Normally the rpms are at 2500 to 2700 at that speed, but it was over 3000 rpm. so after some digging around and trying out a few things this is what i know so far :

1. TCC works normally when driving around the city
2. TCC will disengage after driving on the highway for aboot 10 mins. And only when the engine is warmed up (needle just under the 90 degree mark)
3. When i put the car in neutral at highway speeds and turn off the engine and start it back again and put the car in drive again, The TCC will work for about 1-2 mins then disengage again.

SO, my theory is that maybe theres something wrong with my tranny, i'm no car expert but thats what i think. I guessing maybe the tranny is getting too hot and the compy is telling it to not lock up the TCC or maybe the TCC solenoid is no good.

Anyong got any ideas??

edit: i think its a 4t60-e, not really shure (definitely a hydramatic though)

It is a 4T60E.

After a drive, can you check the odor, color, and level of your trans fluid.

If you have access to a scantool, trans temps when it unlocks would help.

While driving, when it unlocks, pop it into neutral and coast, then turn the car off for a couple seconds, restart, and put it back in OD. Do you get lockup? Does it even try?

i don't have a scan tool (thinking about getting a tech 2 but i don't have 7 grand layin around), so i might head down to the auto parts store and pick up a trans temp gauge instead (cheapest way for me since most scantools sold here only show DTC'* and no actual data.)

gonna go out now and check the fluid. last time i checked was before winter and it was pretty clean.

ok the fluid is good, light red color no darkness to it and is at the correct level.

as for the scan tool, i can't seem to find one that reads the actual sensor data. i can find plenty of the dtc code readers but thats no help to me right now. (doesn't help that my car is OBD 2, weird). and also all the part stores i've been to don't stock trans temp gauges, they "special order" them so i think i'll just order one online was thinking about getting this one: CyberDyne Trans temp gauge

and while i'm at it i think i might as well pick up one of these : B&M tranny cooler (the 9,800 BTU one)

any advice would be great.

I have that same guage in one of mine, and a bigger cooler. But are you willing to drop money on sensors and bandaids when the problem may be a trans issue that could cost you a couple grand?

good point, but i don't have ~$500 for a scan tool right now (currently jobless and local parts store don't rent or scan for dtc'*) so i figured the cheapest way would be to get a trans temp sensor to see whats happening and when, I don't thing i'm going to bother with the cooler untill i know more about whats happening. I hope its not a major problem with the tranny (i hope i don't have to rebuilt it a 2nd time)

Since these trannies are electronic, being controlled by the PCM and all, there is always a chance of something in that dept. hosing things up. For instance, a Code 16, "System Voltage High/Low" will force the trannie into 3rd gear as a protective measure. I experienced this when mismatching PCMs, PROMs, etc and it threw a (false) Code 16.

Not saying that is YOUR car'* problem, but might keep that in mind when troubleshooting. "Fact is stranger than fiction."

This sounds like the common problem with the 4T60-e caused by a valve body issue that can only really be cured by repairing or replacing the valve body. Sonnax makes a kit to address this very problem.

http://www.transmissionpartsusa.com/...-0sc4t60e1.htm

The problem is aggravated by heat. If you can keep the trans fluid temperature down, the TCC will stay in lockup. I had/have a similar problem with my '95. I bought a low pressure drop cooler from bulkpart.com and installed a 180F thermostat. That dropped the trans temperature and keeps my trans in lockup on all but the hottest days. I think if I had bought the 4589 instead of 4588 it may have stayed in lockup on even the hottest days. I see the price has increased about $10 on these, but they are an excellent product with all the parts you will need to do a very professional installation. Here is the link. :

http://www.bulkpart.com/Merchant2/me...de=tru-cool-hd

This is a good fix to try. Cooler trans fluid can only help.

thanks for all the help, i found a parts store that'll scan my car for codes for $15, so i'll see if there are any stored codes in there this weekend. Hopefully it can be cured/patched up by installing a tranny cooler and 180 t stat. (anyone know where to find one in toronto? most part stores carry the regular one-fits-all t-stats). if not it looks like i'm going to have to do a rebuild (if thats the case then i might just start looking for a new ride, with 260K on it, i doubt this will be my last of problems with it.)

ok so i got the temp gauge, installed it and drove the car for the past two days and monitored the temps. At 91C (that aboot 195F) on the gauge the car will "slip" out of TCC lock up, (the rpms will slowly start to climb from 2400 to about 2800 and then kicks out of lock up. the highest so far has been 113c (235F) which is mixed city/hwy driving. average temp when driving on the highway is about 100-105C (212-221F). So i'm pretty shure that its running a little hot, also the temp here has been around the 10-15C(50-59F) mark.

going to the parts store tommorow to have it scanned.