4L80E Only reverse.

[konstantinNeo]

I have a 2000 Chevrolet Workhorse 30P, its a small size bread truck.

Vortec 4.3l v6 with a 4L80E transmission. 

I bought the truck from the bread company itself and worked mostly on the engine, it runs.

Last time I used this truck was 6 months ago. I have noticed that the transmission upshifted a bit hard but I never actually driven a 4l80e anything.

Today I was trying to move the truck, the transmission sounded banging harshly and moving jerkingly, the vehicle advanced like 50 yards, reverse works good, nothing forward, now the transmission is not banging but if I rev the engine It will sorta try to move but only like at 5% power. 

What can I check electrically maybe?

I have no OBD tool.

[davester]

I would suggest just checking the fluid, if it's low (you can't really check it, as you need to drive around to get it up to temp and the transmission has to be working right), just the simple cold-level check, add fluid and see how it works.

 

If it's not low fluid, you might drop the pan and test the solenoids, or go to a parts store and have them check for transmission codes (not all code readers can do this).

 

But like, the fastest, cheapest solution is likely to just slam another 4l80e transmission from the junkyard into it...