Hello everyone. I have a 4.9 conversion with the original 4t60E automatic transmission. The tranny works fine for some 30-45 minutes, then I lose first gear and overdrive. When the transmission cools down again, it starts shifting fine. However, there is no slipage, no hard shifting.
I was told it cannot be the solenoids, as it would lose 1st and secod gear even when cold. Can the computer cause these problems? Temperature sensor not wired? Please help.

Tranny seems to act up with temperature and temp sensor not wired in - I would suspect that there is a connection

The problem seems to appear when the transmission gets warm. I know it is cooling right, as I have both the stock radiation cooler and an aftermarket connected in series in on rear.

,,On the electronic controlled 4T60e,It will not shift properly after it reaches a certain temperature ,if the sensors are not connected,there will be 3 Sensors that control shift ,,the throttle position sensor, the temp sensor and 1 other.. looked it up! speed sensor is the 3rd..
...The car can be driven short distances with out the proper connections ,,but the sensors come into play when the transmission Fluid reaches 100o to 130o .
..The transmission should not function properly with out the sensors partying with the ECM,,its why the e is in the name,,seems like witchcraft or leprechaun magic to me

,,Have you been driving the car ?? did it run OK previously ??
.. these trans are not as rugged as the T125 and the fluid should never be allowed to drop,,Check the fluid ..I assume you did this ..
.. the reverse of the problem,,no 4th when cold I would think TCC ,, of course I don't know crap about Fiero,s Im a guessing .I always think it,s the TCC
..any one having the 4T60e that has been run with low fluid add a bottle of LUBE GUARD,, What with the mass killing & brutal clubbing to death of Fat,Tasty, suculent harp seals you would think the Canadian & U.S.A. goverment would allow Natural whale oil in the ATF..

[This message has been edited by uhlanstan (edited 10-20-2010).]

quote Originally posted by 88FieroV8: Hello everyone. I have a 4.9 conversion with the original 4t60E automatic transmission. The tranny works fine for some 30-45 minutes, then I lose first gear and overdrive. When the transmission cools down again, it starts shifting fine. However, there is no slipage, no hard shifting. I was told it cannot be the solenoids, as it would lose 1st and secod gear even when cold. Can the computer cause these problems? Temperature sensor not wired? Please help.

who did your wiring? was it an injection technologies harness or did you do it yourself? what year and model is the computer from?

if first and 4th are gone, but they used to be there, shift solenoid A could be going bad according to the fsm..... also, if the tranny is a 94 or later, it has an internal temperature sensor which is not used in these swaps. if it has gone bad, or the tranny fluid is getting too hot, it will effectively put the tranny into limp mode, giving you only 2nd and 3rd, even without a command from the ECM...

PS- i see you are located in orlando. if you cannot figure it out, come down to Coral Springs( 2.5-3 hours south of you), I'll help you troubleshoot it. i just went through some major 4t60e troubleshooting with another customer, turned out to be a 94 transmission used with 91 wiring and computer..

Aaron
stickpony@gmail.com
561-201-6191