I just bought a 95 4.3 4x4 blazer with 4l60 in it. I havnt jad much time to tinker on it yet but it needs a fair amount of work. First thing first is getting it to run through all the gears. I would like to be able to fix this tranny but it only grabs 1-2. It also only has 16 inches of vacuum at idle so i am hoping it is the vacuum modulator on tranny but i am having trouble finding information on it. Any help is much appreciated!

 

Blazers are notorious for having vacuum leaks due to the vacuum hoses that supply vacuum to the HVAC and front axle engagement diaphragm leaking due to rot. This is an easy and cheap fix and well worth doing first. You might just want to replace all of the ones in the engine compartment as a matter of course. The hoses under the dash are of a different material and I don't think I've heard of them leaking.

As for the transmission, losing 3rd and 4th (OD) is not an uncommon problem with the 4L60E. I had this happen to me because I burned up the 3/4 clutch pack by towing my 2,200 lb boat and trailer in OD. You might be lucky and have something else be the problem that could be fixed without removing the transmission (electronic shift solenoid?) but don't be surprised if a rebuild or a replacement transmission is necessary.

 

Your truck has the 4L60E transmission where the 'E' stands for electronic controls as such, vacuum is not directly applied to the transmission.

When you say that all you have is 1st & 2nd gear, does this mean that you do not have reverse? If so, then the most likely cause of your problem is a failed reaction sun shell which is a common failure point in these transmissions. If you still have reverse, then it is possible that the 3-4 clutch pack is toast or possibly a problem with the sprag responsible for power transfer in these gears. To repair either failure mode, the transmission must be removed and disassembled.

If you choose to rebuild your transmission, be sure to pick up 'The Beast' sun shell which is designed with more material around the typical failure points.

 

I still have reverse and i was just considering a smaller problem cause i was told the transmission had been rebuilt but i bought this vehicle figuring id be pulling the tranny out and replacing. What are the odds its a shift solenoid and how can i diagnose that? Thanks for the replys already!

 

Also the speedometer isnt working so im wondering if vss is bad. In my 07 silverado when it when bad i lost everything past 2nd gear so is that possibke the trans is getting confused? Im about to pull it in the garage now and start tracing it back

 

I'd tackle the speedo problem first. Without a speed reference, weird things can occur. It is also possible that there is a problem with one of the solenoids. If it was rebuilt, I would hope they would have at least checked the solenoids while they had it apart. A quick resistance check is all that is needed to verify that they are good.

 

The vss was completely unplugged! Just had it shift into 3rd forsure but not enough speed for od. It was still slipping a little though. You guys know of anything i could do for some life out of this trans?

 

Is the ses light on? If so, are there any trans related codes?

 

No light and no codes