Hi, This is my first post. I have a 2006 H3, it's been a great ride and I LOVE it. But my baby is parked and I'm driving my husband's pick-up for now. I was in the H3, at a stoplight and when I went to move forward, it wouldn't! After a moment's panic, I shifted it (automatic transmission) into 3rd, and it moved forward. Was still at the stoplight during this. Then, when I pressed on the gas, it again wouldn't go. So I shifted it into 2nd, and was able to proceed into a nearby parking lot. It didn't make any weird or loud noises, just wouldn't go in drive or 3rd gear. We would up having it towed home and here she sits. We just had like $3,000 of work done on it, well fairly recently. During this time all fluids were changed. We really don't have the cash currently to be taking it back to the shop for a rebuild/replacement of the tranny so it's been sitting for like 2 months. Recently a friend came over with a fancy scanner. I wasn't around at the time but my husband said it didn't show any codes (and no check engine or any other lights have shown during my stoplight episode) - also have onstar monthly diagnostics - they don't show anything either. Anyway, husband said he and friend were able to do something ( sorry I don't know what it was) to make all the gears work and friend said it was the solenoid (not sure which one...). It currently only is back to 1st, 2nd and reverse for working gears. My question is (finally!)….. could it be the solenoid or could it be the forward sprag? I ask this because troubleshooting seems to point to maybe the sprag, The more I read online the more confused I'm getting. Maybe should we just replace them both? Husband's going to be doing the work. Thanks for any suggestions! I would like my ride back.

 

How old is your radiator? Have you pulled your trans dipstick and made sure the fluid doesn't look pink and milky? Not to alarm you but when I had these same symptoms (I was in a drive thru when it happened!) my radiator failed internally and the trans fluid and coolant mixed, completely toasting the transmission.

 

Welcome to HF.

You did not provide us with how many miles are on the truck or when/if the Trans fluid and filter were ever changed? Without that, you are asking for wild guesses.

GM 4L60E Auto Trans in a 4X4 truck are gonna need a rebuild somewhere around 100K miles depending upon use, driving habits, and maintenance.

If the truck has more than 80K miles, what you describe is typical, sound like you need a rebuild, doesn't matter what the exact answer to your question is, if it won't shift to 3rd, it likely will not fully lock (into overdrive) either.

Good luck.

PS.... O Star and its diagnosis are useless.

 

Bad low/reverse sprag would mean it would have issues with choosing gears manually, but full auto (drive) would probably be okay. But also depends on how much it has let go; a bad sprag can be okay because they are so tightly sandwiched, but any play on the shaft and all of the sprag rollers can cut loose and they will take out EVERYTHING. This just happened to me when I was in the wilderness, and by the grace of all that is holy I made it 90 miles home without the sprag grenading. I would definitely avoid driving it and have it towed directly to a top-rated specialist for a proper diagnosis. When you were driving it, was it making any new noises?

 

Had new radiator installed last fall, just checked dipstick yesterday, fluid's red/auburn. Hummer has about 170,000 miles. Trans fluid & filter changed along w. the new radiator. No it didn't make any noises, sounds quiet as usual. We're going to try a new solenoid today.

 

At 170K miles, you need a rebuild, no question in my mind. Consider yourself fortunate to get that many miles before needing one.

 

I'm sure your right. I just have one other question. Which solenoid is it that controls Drive & 3rd gear?