Howdy,
My son's 95 4WD Blazer has a tranny that will shift 1-2 then free wheels when it trys to shift to 3rd. Motor just revs. We checked the fluid level and it's right where it should be. The Blazer has about 85,000 miles on it and has been kind of quirky when it comes to the transmission anyway. Early on at 70,000 miles it would stick in a gear and then shift hard. It has always shuddered in reverse.
I've searched and didn't find this problem. I read about the downshift solenoids going bad but I'm not familiar enough with this tranny to know what's going on inside. My first thought was to pull the pan and change to transmission filter/screen. I'm assuming this one has one. Anything else to check while I have the tranny pan off? Any insight on what to check would be appreciated.

NRA

 

If this problem just started out of the blue, I would suspect an issue with the valve body.

It could be the 2-3 shift valve train being stuck, or the 2-3 accumulator valve sticking. Other valve body issues that can cause this condition include gaskets and/or spacer plate incorrect, mispositioned, or damaged or a face flatness issue, but these items rarely show up out of the blue.

It could be an issue with the 3rd accumulator retainer and ball assembly not seating.

Could also be a problem with the 3-4 clutch pack.

 

I don't claim to be a auto mechanic but I can tell you from personal experience that servicing my tranny never helped my problems. Actually on one that was shifting fine immediately started giving me problems after the tranny shop serviced it. Lot of smart guys on here though. Hope they can help you out.

 

Thanks for the responses. I read on another forum that faulty electrical connections can cause shifting problems also. Also poor grounding. Where would I look for these connections? Another forum said to reset the computer too. Any feedback on those ideas?

Thanks, NRA

 

I would suspect an internal problem with the valve body or the 3-4 clutch pack (most likely) as I stated. The trouble shooting chart for your condition does not call out any of the solenoids.

The wiring harness for the valve body is inside the transmission pan. As far as grounds go, there are a few. If you really feel like digging into it to that extent, you'll want to get a reference manual or something similar (AlldataDIY.com). But this is the point where I'll say that you really should get it diagnosed by a competent transmission shop.