Within the last couple of weeks, my 2000 year 1500 4.3L V6 Silverado seems like it's braking when coasting. If I take my foot off the gas pedal when in motion, the truck seems to slow a little, then coast, slow a little then coast, just like as if i am pressing the brake on and off. It does the same thing if I move the gear shift to neutral while moving too, so not a brake issue. It seems to do it any speed and with the gear selector in 1, 2, 3 or D. Does it sound like my gearbox is finished or should I go get a flush and filter? The truck has 110k on the clock.
Thanks.

 

It sounds like the torque converter is unlocking and locking under deccelaration. Do this, go cruise it on the highway and get steady at 60 MPH. Keep your foot on the gas and with the your other foot, tap the brake a lil and watch your RPM's. You should see it raise bout 200 RPM's. Thats when the torque converter unlocks. Then it should lock again, after about a few seconds. Check that to see if it is working properly.

 

Thanks for the reply. If it is the TC unlocking and locking what is the fix??

 

Well it could be the solenoid in the valve body which is bout $17 bucks. Or the TCC itself. Might see if a transmission shop has a scanner and see if they can test it while on the fly.

 

Yep, got on the highway today and got the old gal up to 60. I put my left foot on the brake pedal while continuing to maintain constant acceleration. The RPM did indeed rise 200 or so. Do you think getting a transmission flush and filter would make a difference or is that nothing to do with the TC?

 

In most of such gear problems, you may discover that every other gear will turn into the same direction.

 

Well thats normal. That was to see if it works on command, which is good.

 

The temps have got a lot warmer here and the problem has mysteriously fixed itself ! So I guess time for a fluid change then !! Our 2006 minivan's steering was really stiff when it was cold. Recently had a fluid flush on the steering fluid and that fixed it. So I'm hoping it was a cold problem. Living in ND, you just don't wanna know about these !!

 

Get just the filter and drop the pan fluid change. And see how that works. If its good then go back and get the fluid flushed. What Im sayin is take baby steps with servicing the transmission.

 

so true - I once asked for my diff oil to be changed. The technician said wtf do you want me to do that for? I said just go ahead and change it. Should have listened to him - 3 months later diff was dead !!