Overdrive slipping

pjmmoore · February 10, 2007

Recently my truck has been randomly slipping out of overdrive. I've got an '02 Silverado 4.8l w/automatic. All aspects of the truck have been well cared for, including the transmission. Problem started within the last week and the only that's changed here is the weather - it's been mighty cold here in Baltimore for the last week or so. Could the extreme cold cause the slip?

Norseman · February 10, 2007

Recently my truck has been randomly slipping out of overdrive. I've got an '02 Silverado 4.8l w/automatic. All aspects of the truck have been well cared for, including the transmission. Problem started within the last week and the only that's changed here is the weather - it's been mighty cold here in Baltimore for the last week or so. Could the extreme cold cause the slip?

The most likely cause is a worn clutch but, I'd take it to a trannie shop and let them look it over. Hard to trouble shoot transmission problems over the net. Good Luck.

redvett · February 10, 2007

Are you sure its the OD and not the TCC modulating? Modern day vehicles modulate the TCC so you cant feel engagement. Try driving in drive and see what happens and watch your tach closely.

67ChevyRedneck · February 11, 2007

I noticed something similar with my truck when it was real cold. It would go into 4th, but the TC wouldn't lock. Thanks to the fellas on this board I learned that the TC won't lock until the tranny reaches like 170 degrees or something like that. I now leave my truck in 3rd on cold days until she gets up to operating temps. It might be that simple, or something more serious the others have mentioned.

cyoung1253 · February 11, 2007

I have also noticed that the TCC in my '05 doesn't lock-up till the trans gets a little heat in it. Been sub zero almost every morning this week Brrrrrrr.

CapitalTruck · February 12, 2007

By "well maintained" what do you mean? Have you done fluid changes every 25,000? If you have 100,000 on that truck and you haven't changed the tranny fluid yet...lookout!

2004GMC1500CC · February 12, 2007

By "well maintained" what do you mean? Have you done fluid changes every 25,000? If you have 100,000 on that truck and you haven't changed the tranny fluid yet...lookout!

Mine isn't called for until 50K on the extreme schedule. They do come with synthetic from the factory now.

pjmmoore · February 12, 2007

Thanks, all, for the feedback. I will keep an eye on how and when the trans hops out of OD. I'm hoping that it's the cold weather affecting it and not something more serious.

svensk · February 12, 2007

It is the weather. It has been sub zero F here in MN for over 2 weeks and will not even bother putting it in Drive when I take off. Plus its a lot of fun to drive in 3rd sometimes.

dreman · February 12, 2007

There's a problem with the 4L60E trans. that allows the TC to unlock occasionally. It's apparently caused by a worn shuttle valve in the valve body. Mine started doing that when it got hot, and then the trans. goes into full panic mode, raising system pressure and causing HARD shifts. The fix is to get the valve body repaired. I sidestepped the issue by taking care to keep it from getting hot. It still drops out of lockup once in a while, but the trans. doesn't panic. It's been doing that for over a year, and maybe 50,000 miles.

Billdog350 · February 12, 2007

My 4L80e is doing the same thing because of the cold temps here in CT. Once your engine is warmed up, just get on the gas as much as possible and it'll dump lots of heat into the tranny (thru the slipping converter) and get the tranny up to temp and the TC will lock up. Lately the engine temps need to be up to at least 160+ before my converter will even think of locking. Tranny temps stay cold though...my gauge doesn't even hit 100 sometimes.

dreman · February 12, 2007

I have no idea what problems are associated with automatic transmissions in cold weather. We don't have "cold" weather here in Houston. If you want hot, we usually have lots of that!