94 Chevy 4L60E Transmission Problems

[bigrichard]

I've got a 94 1500 4X4 that has recently developed some tranny issues. 1st problem is it won't shift into second gear automatically or manually(using the column shifter). If I wind it up to about 4k and take my foot off of the throttle it then shifts to drive. I am thinking it may be the shift solenoid but I poured some lucas in it to loosen things up and it didn't help at all. The second problem is when it is in overdrive it shifts back and forth between drive and od and will not stay in one gear even on flat land. The rpm fluctuates by about 800 when it does this. The tranny is relatively new with only about 45k on it and these problems both developed overnight and simultaneously without warning. I can still drive it around and it works fine but I just can't use 2nd or od. I pulled the pan and there is a very small amount of metal on the magnet so I know the clutches are not worn out as I have never changed the fluid since being rebuilt. Is there anyway I can test the shift solenoid? Any ideas would be very much appreciated before I have it rebuilt.

[jdmccright]

Sounds like the tranny is in limp-home mode which should set off the check engine light. The rebuild should have included new solenoids. I'd take it up with the shop right away and see what they can do and under warranty hopefully. No trouble codes? Even the '94s had simple tranny codes, I believe.

Lucas won't help an electronic problem. That stuff is for helping to increase line pressures and refurbishing old seals, gaskets, etc., which should be new in your rebuilt tranny.

Hope this helps!

[2000CAYukon]

Does Reverse work?

//2000CAYukon

[bigrichard]

I checked for codes but it is not throwing any. I am still driving it around as it works fine it just doesn't have 2nd and OD and yes reverse works. I am thinking it is definitely the solenoids as the shift from 1st to drive is still really crisp so I am going to start with that before I do an overhaul as most rebuild kits do not come with the solenoids. thanks for the input guys.

[2000CAYukon]

I don't think your issue is a solenoid. Since reverse works, the sun shell is not broken, the common area for 2nd and 4th is the 2-4 band. If the band is broken or worn, you will loose 2nd and 4th (OD).

In 1st gear both Solenoids are On. For the Shift to 2nd, A solenoid is turned Off. For the Shift to 3rd, the B Solenoid is turned off. For 4th, A is Turned back on.
----1st, 2nd, 3rd, 4th
A is On, Off, Off, On
B is On, On, Off, Off

A bad "A" solenoid would mean losing 1 and 4 (stuck on), "or", 2 and 3 (solenoid will not turn on or electrical issue).

A bad "B" solenoid (stuck on) would loose 3 and 4, or 1 and 2 (electrical).

Since the tranny has relatively low miles, I suspect the anchor for the band broke or the band itself broke. Another possibility is the 2-4 servo is not working. Fluid entering the 2nd gear circuit is fed to the intermediate servo which applies the band. The band is not applied in 3rd gear. Fluid entering the 4th gear circuit is fed to the 4th apply servo which applies the band. It is rare the both seals would go out at the same time. The servo is accessable without dropping the tranny so it is worth it to take a look at. Or have someone take a look at it.

A broken anchor of band will require the tranny to be removed and disasembled.

//2000CAYukon