My 2005 duramax has 70000 miles on it. About a month ago I noticed that when I should be going 50+ it registered 20-0. I was only 1 mile from the boat ramp. It worked fine on the way home. Temp was below 32� that morning.

Yesterday on the way to the lake it did the same thing the temp was 27�. The town before the lake had a 4 way stop. After going through it the speedo seemed to work fine.

It worked on the way home.

It works today.

Any ideas as to what I should do other than taking it to the dealer.?

I don't know if they still use cables or if it is all electronic. If it is cable driven, sounds like your cable is sticking or your gear is broke. I had a 67 chevy PU that is did the opposite. It was cold out then also. Anyway, it started squelling and the spedo pegged out (If I remeber that spedo topped at 80 MPH. I was only going about 15-20 MPH. I can't remeber if I had to replace the cable or the plastic gear or both, that was 30 years ago. Might be that you just have moisture in your cable. If that's the case you could spay some WD in there to dry it out and then put some lube in it.

My 05 Tahoe did the same from time to time. It was electronic
and it was the instrument cluster. The Tahoe had 55,000 miles
on it when that happen.

I also have an 05 Tahoe 85k, dealer service said it was a stepper motor in instrument cluster. Replaced cluster, fixed

There is a guy in the DFW area that will replace the stepper motors for around $125. He advertises on Craigslist. If you aren't in DFW, the stepper motors can be bought off EBay. Several Chevy forums will have How-to's on replacing them.

Thanks for the info. I just noticed I put this in the wrong forum. Sorry about that.

You're right, the problem is the stepper motor.

However, at your mileage, you should just take it to the dealer. There is a recall on chevy speedometers in the Tahoe, Suburban and Silverado. I have a 2004 Silverado and had mine replaced awhile back. I was told that dealer would cover part and labor under 70k miles, part only between 70k and 80k and nothing after that. I had to pay an hour of labor to get the new instrument cluster installed in mine.

I didn't realize it at the time, but they had to program the mileage into the new cluster. I should've slipped the installer a $20 and told him to knock a few thousdand miles off.

Hey thanks for the heads up. I'm heading for the phone right now to call the dealer.

I called the dealer and they looked up the vin# it isn't covered. They gave me Chevy's 800 service number and I was told by them to take it to the dealership and have it fixed but they would not cover the cost.

For a $500 fix I think I'll wait a while.

That stinks. I'd call that guy on craigslist. I had heard some good stuff about him before I found out about the recall.