Sometimes the speedometer needle will jump to 10mph on engine start up and read that high driving until the next start up. The next time it may start at 20mph high, the next time it may start at below 0mph.

What's likely to be the problem, how hard is it to fix, and how much should I expect to pay for the part?

Thanx,

KY Trailblazer

 

This is likely a failing cluster. You should be able to pick up a cluster from the junkyard or online someplace for a heck of a lot cheaper than the dealer.

 

OK.... I am ready to make time to deal with this and this is what I've found out over the last couple days.

The cluster needles are driven by stepper motors that are soldered into the printed circuit board for the cluster. There are several sources on Ebay where you can buy the motors. I'm pretty good with a soldering pencil and figure I'll buy the motors and attempt the repair myself.

My questions are, How involved is pulling the dash apart to get the cluster out? I took the kick panel off the driver's side and it looks like I can take some screws out across the front and take out the center panel that goes over the radios and heater controls. Is there some other obstacle course there that I don't see? Otherwise it looks like about a 4-6 hrs job easily tackled on a weekend to keep the car from being out of service.

The other one is....if I get a cluster from a junk yard, will that change the mileage on this vehicle?

KYTrail....

 

I just wanted to say that in the blazer they arent soldered in they just press into metal clips. Im not sure about the trail blazer. However my blazer had the same problem and it wasnt the stepper motor it was the cluster going bad. I tried a new stepper motor that worked with a different cluster but didn't fix the problem, it was specific to that cluster. I had to get a cluster out of another blazer and put it in to fix the speedometer. And yes the cluster from a junkyard will have the mileage of the vehicle it came out of.