'99 Silverado Specific Hard Shifts?

Dawgs007 · July 12, 2017

Hey guys, I'm having a heck of an irritating issue with my '99 Silverado 2WD 130,000mi. I had posted last week about having bought this truck and the transmission was leaking tranny fluid. Well, I got that figured out (tranny cooler line was cracked).

Now that the leak issue is fixed, it seems that it occasionally has a hard shift from 1-2 (2-3 also sometimes). If I accelerate at a faster rate, it doesn't shift hard... but if I ease into it, the transmission seems to shift hard in those gears. Fluid is full.

The only things I can think of is:

1.) Fluid got too low while it was leaking (leaked quite a bit) and caused damage

2.) A sensor maybe got coated or messed up when I cleaned out my throttle body and is giving false readings?

It didn't seem to shift hard 200miles ago but is now under my ownership and of course has issues ( ;( )

Is it true that if you leave the battery disconnected for long enough it will reset the CPU system? Or would a code maybe appear on a OBD-II reader even though the check engine light isnt on?

Thanks for your help guys! I just can't afford the vicious cycle of diagnosing at multiple shops and useless 'fixes'.. thanks!!

Dnt · July 12, 2017

You are in the dreaded transmission death spiral. Clutches are worn, whatever you do at this point do NOT change the fluid, new fluid contains acids for clutch break in and that will only accelerate the death spiral. Use your funds for a re-manufactured transmission. It will most likely run another few thousand miles but if you drive it very long a new U Joint is in your future too. Check engine light will come on once the clutches wear a bit more and you will have a trans code.

Dawgs007 · July 12, 2017

You are in the dreaded transmission death spiral. Clutches are worn, whatever you do at this point do NOT change the fluid, new fluid contains acids for clutch break in and that will only accelerate the death spiral. Use your funds for a re-manufactured transmission. It will most likely run another few thousand miles but if you drive it very long a new U Joint is in your future too. Check engine light will come on once the clutches wear a bit more and you will have a trans code.

I know it's just how it goes but that always sucks to hear! Lol. Is this about a normal mileage for this to happen?

SouthernSilveradoGuy85 · July 12, 2017

When I had a '98 it did this and the only way to stop it was to pull over and turn it off for a minute or 2 then it would shift fine. It did that for maybe 10-15K miles or so and it finally gave out.

Dawgs007 · July 12, 2017

When I had a '98 it did this and the only way to stop it was to pull over and turn it off for a minute or 2 then it would shift fine. It did that for maybe 10-15K miles or so and it finally gave out.

Maybe this is me just being optimistic (I hope not!!), but it isn't nearly bad enough to make me pull over (yet!). It is just kinda light currently. It isnt a slip, just like it is hard for the gear to engage properly at low acceleration. Is that how yours was? It just doesn't seem as severe yet as to pull over for any reason!

Dnt · July 12, 2017

Sorry man I had several of these do the same thing all at varying mileage one held out to over 220k before it death spiraled. One went out at 80k you just never know. If this is just starting to get noticeable and you do not have a check engine light yet then most likely you have some time and several thousand miles before getting too excited. When you get tired of cringing waiting for the super harsh upshift, swap out the trans.

Dawgs007 · July 12, 2017

Sorry man I had several of these do the same thing all at varying mileage one held out to over 220k before it death spiraled. One went out at 80k you just never know. If this is just starting to get noticeable and you do not have a check engine light yet then most likely you have some time and several thousand miles before getting too excited. When you get tired of cringing waiting for the super harsh upshift, swap out the trans.

WELL, it does suck to hear but luckily it is mainly just for hauling my mower, small trailers, etc. I hope to still get awhile out of it because I doubt I sink more money into it with a transmission with the miles it has on it! Greatly appreciate the honesty though!

Dawgs007 · July 12, 2017

Is there 'hidden' codes that a transmission shop could hook up to and see something even though the check engine light isnt on? Just wondering what I should do currently.

Dawgs007 · July 14, 2017

Just as an update, took my truck to a shop today just to look over it and tell me what seems like it's causing it.

He took it for a drive and was able to get it to happen a couple times and determined it's just something I'll have to deal with. He said it's likely the shift point pressure combined with me letting off the gas a little to allow it to shift. As far as he can tell, my tranny isn't 'doomed' and that for 130,000mi it's still running well.

Just an update if anyone has the slight hard shift 1-2 and 2-3 sometimes!

Dawgs007 · July 17, 2017

As an update to help others, I think I fixed the hard shift in 2-3 problem. I drained out some tranny fluid since it was high on the dipstick and ended up siphoning out approx. 1.5qt (ridiculous)! It appears my issue was a pressure issue internally from what I can tell.