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Recalibrate Speedometer on 04 2500HD?


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Many moons ago, I upgraded my tires from the stock 245/75X16 to 265's.


My speedo was about 2mph off, which I adjusted to.


My question is, I had the instrument cluster replaced under warranty at the dealer.


The first thing I noticed was the faster I drove, the more the speedo was off according to my GPS. When it showed 70mph, I was doing close to 75.


I called the service advisior after a couple of exits on the interstate, and he said there was no adjustment, and after I drive it for a while the computer would correct itself.

Is this true? After about 100 miles, it seems a little better, but not the way it was, and I don't feel like getting a ticket.


I go out one morning, and as I start the truck, I happen to be looking at the cluster, and notice there is no check engine light when I start the truck.


The manual says that if you turn on the ignition without it running, it stays on to check it untill the truck starts and then should go out.


There is no light period, so I call him again, and he says that there is no way to fix this, and the cluster would have to replaced again.


So I ask him this time while they are replacing it if they could adjust the computer for the 265's. He said that could be down. I know the same truck 3500HD SRW comes with the 265's.


So is he right about the computer adjustment, or does the truck still use a gear that would have to be changed to correct the speed discrepancy?

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The dealer can adjust the speedo for any tire size or gearing that was a factory option. If he refuses you can have it adjusted using a handheld tuner. You don't swap a gear in the trans anymore

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This gets stranger yet!


I haven't used the truck for a few days, and went out to start it, and what do I see, the check engine light goes on and off like it's suppose to! It hasn't worked at all since the new cluster. I'm hoping that I don't have to go back to the dealer again. It's 60+ miles one way. At this point I'll live with the speedo.


He's suppose to get the replacment cluster next week sometime, so I'll just keep checking that it works.


I love this truck, but it's had it's fair share of electrical gremlins.

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