Hi all...hoping someone can help me out with a weird transmission issue...

So, vehicle gets warm and the problem starts, although intermittent but frequent.

Basically as I'm cruising in OD and let me foot off of the gas, found that the trans goes into neutral...when I re-apply a bit of gas you can feel the trans re-engage 3rd gear, then slide back into OD.

So when it's doing this, and you happen to come to a full stop, the truck is actually sitting there in neutral (take foot off brake...it sits there not moving). Then apply a little bit of throttle and you can literally feel the trans come back through the gears into 1st with a couple shifts.

So all-in-all, trans keeps netutralizing while driving. Is there a TSB or some type of re-flash that fixes this? Seems like a computer issue. Trans performs fine otherwise.

Thanks!!!

that's an odd symptom! It sounds electrical but many of these trans don't have too much electrical components to them. For one you should put year and motor size so the forum can better help, the same trans in various yrs change some throughout yrs.... as in earlier models have much less electrical components and after 90's they added more (solenoids and switches).... if you have the earlier type it's possible a TCC switch issue? I hope someone chimes in, because I haven't had much luck in this forum myself.....

Thanks. It's a 1999 4.3L 4X4 but I'm driving in 2hi when this happens...haven't hardly used 4X4 since I bought it a few weeks ago.

I have an 86 blazer 350- 700r4-4wd. Slips in 3/4 proubly needs rebuilt. I was thinking about swapping out to turbo 400. what are your thoughts. Thanks as this my first blazer. thanks for all info here.

For one the TH400 is only 3 gear with no OD so fuel economy is going down right there. Gear ratio is another thing to look at, which I am unsure about and the updated version of the TH400 is the 4L80-E which wouldn't be compatible as a straight drop in and go due to your Blazer is lacking the correct wiring harness to be able to hook up to the electronic trans. IMO the best way to go would be to stick with what you have, the 700R4 or possibly the '87+ because that yr and slightly newer were made better than the '82-'86 ones....as in all the kinks were worked out. And I'm almost certain that there is no other electrical harnesses to have to worry about, providing the trans you get was mated to the same size engine you have (many made for 4.3ltr NOT compatible with yours). Good Luck

So sorry to see nobody got back to you yet either... :( and from what I've read on the other threads, there are some pretty sharp trans ppl on this forum. Maybe everyone went on vacation at the same time.... :-/

How many miles on the vehicle?
Since it's temperature related I would think something mechanical is worn either in the valve body or the forward piston. I'm no expert by any mreans though. Have you verified fluid level and engine sensor operation?

It has just over 200,000km...yes fluid level is up...I tried putting a Lucas in it but doesn't seem to have done anything. I continue to drive it like this...you can feel when it starts to happen because you will roll up to a light and you can tell ur in neutral...so while waiting for te light I just apply a bit of throttle while still in the brakes and you can feel it shift back into first. Then next light it could be gone again! Then back again...so weird. No check engine or any other lights.

To me sounds like a pressure related thing

97 Blazer Wont Shift
 

Built a 97 blazer for my girlfriend. Vehicle ran great for 2 days, was a little delayed shifting out of first gear. Sometimes it would shift out of first between 3000 rpm 3500rpm, other times would be between 4000 & 5000 rpm. Well went to drive it yesterday & it would not shift out of first gear at all. Reverse works fine. Think it caused me to spin a rod bearing because rpms were high at times & was about 2-3 miles from home. So i know how to fix motor, will pull it & put new rods & mains & new oil pump also. But don't know much about transmissions. I have had some issues with my 97 Jimmy but mine was ignition switch harness, after tranny shop installed all new solenoids & it still done the same thing. I have no engine codes, & i had just changed fluid & filter, also did corvette servos install, with a new B&M supercooler. Also have installed new igntion switch harness. Talked with my uncle, he looked up on Alltel & said it sounds like the valve body.Any help appreciated. Thanks
https://blazerforum.com/forum/attach...ine=1373308677