1996 Blazer 4WD, transmission won't shift into third or fourth but if I remove the transmission fuse (which puts it into third because of electrical loss) the car will move. How do I fix these so called "Servos" which were mentioned in this post linked.

Other than that I believe it could just be burnt up clutch pack which would require a rebuild. What would a decent price be for a rebuild and should I request a heavy duty kit or just let them have at it?

https://blazerforum.com/forum/1st-generation-s-series-1983-1994-tech-40/93-s10-blazer-no-3rd-4th-gear-69059/

 

When I burned up my 3/4 clutch pack because I towed in overdrive I had my local transmission service shop do a rebuild. I tow 2,200 lbs of boat and trailer up and down some steep grades (one is 1,700 feet in 6 miles) so I told them I wanted a shift kit and quality parts. They also installed an extra fluid cooler. It cost me $2700.

Are your symptoms that when the transmission tries to upshift from 2 to 3 that it slips resulting in the engine revving? If so then the 3/4 for clutch pack is likely bad. If not, then perhaps it is the servos but I can't be sure of that due to lack of first-hand experience with that failure mechanism.

Here is a simple video that explains the burned 3/4 clutch pack: Here's another video that looks to have a good breakdown on some of the key 4L60E components:

 

Yeah not sure.. I know for a fact that it was in overdrive at 55 and if you give it gas it just revs up the car, I'll have a video if it tomorrow added to the post and you can see if you notice anything. I had to unplug my ECM and it was rough getting the brittle cables out, I wonder if that could've done something. The reason it was out of service was because the transfer case input seal went out causing the transmission fluid level to drop. Anyhow, I'll have the video added tomorrow and you can tell me what you think! Thanks for the response.

 

Ok so I think I actually have third but it won't go to fourth/slips out of it? As soon as it gets to four it either acts like it's in neutral or jumps between 4 and three. Here's a video.
https://streamable.com/1cfmmp

 

Hmmm. I'm not so familiar with that symptom. Perhaps someone else will be able to help. Have you taken it to a place that could read all of the codes for the engine and transmission?

 

Not yet, there doesn't seem to be a check engine light, I assume only real nice scan tools unlike the autozone one cam only check transmission codes?

 

Yes, auto parts stores often have scan tooks that can read codes that will not set tbe check engine light.

 

I got a bunch of codes but when I reset them and drove none came back

 

Welp it's dead. RIP 3/4 clutch pack. I was never taught to check while running. It died before I even messed with it to begin with. The seal went bad causing the transmission fluid to drop which burned up the 3/4 clutch pack causing the fluid to look darker. When I fixed the seal and put it back together the measurement on the dipstick always came back correctly. However after reading today that it has to be checked while the car is running I was able to pour four quarts of transmission fluid into it before it even reached the hot line. So bottom line, transfer case input seal went bad causing the clutch to burn up making me lose 4th gear, I'm guessing the metal shavings allowed me to slightly keep three. After correcting the fluid and driving fourth gear worked fine and then it disappeared along with third.. it's a sad day for my 4l60e.

 

REBUILD TIME! Make sure you really really inspect the planets, replace all plastic rotating assembly components with metal equivelents, Wide bands/Bushings, etc during the rebuild, and i personally would recommend disabling PWM Torque Converter lockup and an Upgraded Sunshell.