Folks, I need some help on this. Hopefully someone has seen this. This just started happening this morning.

My transmission is shifting real hard from 2nd to 3rd, and it doesn't want to (for lack of a better word) freewheel when you let of the gas. Instead of the RPM's dropping down to 1000-1500, it stays at 2000. If you come to a stoplight or something it will finally drop back down, but out on the highway it's not doing it.

What gives here guys? I need some help here. I've got to figure out what the problem is before I drive it any more.

 

how bout' you at least drive it to the dealership and let them try to figure out what is wrong. if you're under warranty...what's the big deal about driving it??

 

Wooo there Troy. You've really got something here. Hmm... let's see... take it to the dealer, umm... no. They're going to charge me an arm and a leg just to look at the damned thing, and no it isn't under warranty. I can't afford to write the dealerships around here a big fat check to tell me that it's not working right.

Sorry for being a smartass but I was looking for something a little more constructive like "I've seen that before and it was caused by..." or "I think there's a TSB on that, you might check..." otherwise what's the point of me posting the question here.

I was kind of hoping I could find a way to fix the problem on my own without forking out a bunch of cash that I don't really have, or atleast find someone who maybe knew something about the problem.

 

What have you done by way of mods to your truck? Any chance you put in a shift-kit or chip? Let the wife drive it?

 

That's a negative Bruce. No mods and the girlfriend has only driven it once in the last couple months. The truck is completely stock. 65,000 miles and my foot is a little heavy. I found a "friend of a friend" place that I'm going to take it to tomorrow and see what they think.

When I went home for lunch I checked it out a little more.

Fluid level is good. Color is good. I just had it serviced about a month ago, give or take a few weeks.

Tranny will freewheel out of every gear except overdrive. If it's in OD, the engine stays at speed even with my foot off of the throttle. This does not happen in lower gears at lower speeds. In all other gears if I take my foot of the gas the engine drops back down to about 1000 RPM's. Also, I said it seems to be shifting hard from 2nd to 3rd. While that's correct, all shifting appears to be a little jerky, but that's where it's most noticeable.

For Troy's benefit, the "big deal about driving it" is because I don't want to aggrivate the condition.

Thanks for the response guys. Hopefully the info above might help a little.

 

can you tell whether or not the torque converter clutch is locking/unlocking like it should?? it almost sounds like the clutch is not locking up at highway speeds...

 

Troy, that may very well be the case. It's really hard to say/tell.

At highway speeds it's behaving normally except that the engine doesn't idle down. It even kicks in and out of O/D just fine using the button.

Keep it comin', I've got to go make some calls.

 

Alright, sanity check here guys. I know that it shifts hard from 2nd to 3rd, that's still there but this O/D thing is becoming a blur and I'm almost starting to wonder if it's behaving normally.

I need to know what your trucks idle down to if you're doing say 70 mph on the highway and you take your foot off the gas. Mine is riding right around 2k and I'm almost starting to wonder if that's normal and I'm confusing myself. Help.

 

That part is normal. The engine should not drop to idle with your foot off the pedal when it's in fourth gear.

As for why it shifts hard, I dunno.

 

Are there any trouble codes. It may not be your tranny. The computer tells the tranny what to do. Good luck.

Pete

 

Mark, Peterblt, I agree with your assessment on the overdrive. I guess it was my nerves or something yesterday. After driving it around this morning I pretty much came to the conclusion that it was behaving normal. However the hard shifting isn't normal, that I know for sure.

I don't have the code reader to pull the code on the computer, but I agree that it could very well be computer related because the computer tells it when to shift. That was going to be the next thing I have checked. It really is only present between 2nd and 3rd, all other gears are smooth, so it's possible that I can get it adjusted (within the computer). That's the next thing on my agenda.

Thanks gentlemen.

 

this is a long shot, but you might try disconnecting the battery for say an hour...then reconnect it and go for a drive and see if there is any difference in shift quality. i know this works on some electronic trannies (especially chryslers) as it resets the brain.

my s-crew has never shifted hard from 2 to 3 unless under wide open throttle...but it does occasionally shift harshly from first to second gear...fwiw.

 

You said you had the tranny serviced.......did they use the correct Dexron fluid????? They are all the way up to like Dexron 5 I think, did they add/replace the correct one?
just my two cents....

medic

 

Isn't Dextron for GMCs? Hope you used the proper Mercon ATF

 

yeah, and you should use mercon V...