Truck Guys I need your help with an 05 Trailblazer LT

**5.7literMustangEater** · 01-25-2008, 02:41 AM

Ok here is the deal, I got my wife a 2005 Chevy Trailblazer about a 1 1/2 years ago. She called me yesterday on her way to work and said the speedometer wasn't working right.
Well this is the problem; the speedometer will not go lower than 35mph and it goes up to about 80mph when she accelerates to 25mph. My question to you all is what could be causing this? Is it a speed sensor, relay etc... She also mentioned that the transmission seems to be shifting incorrectly. Please any help would be great because our warranty only covers the motor and I want to know what type of cost I'm getting into to fix it. We bought it used so the factory warranty had already expired due to mileage. Thanks in advance for your help.

**cabel** · 01-25-2008, 03:09 AM

The fullsize trucks have bad problems with the cluster doing that but I never had a Trailblazer do it. Try unhooking the batt for 5 min and it should go back to 0. For how long it all depends.

**5.7literMustangEater** · 01-25-2008, 04:14 AM

I'll give it a try. Hopefully that's all it takes, but knowing my luck it is probably something else. I'm going to look at the sensors, relays and fuses to see if any of that may be the problem. Thanks for the input.

**Nitrous** · 01-26-2008, 06:35 AM

You also need to scan the PCM for any codes eventhough the light isn't coming on. Sounds like the VSS is acting up causing it to shift out of wack. I don't think the cluster would cause a shift issue but I've been wrong before. LOL

**01pewterz28** · 02-02-2008, 07:14 PM

Not sure if it has any relation but my wife's 05 Trailblazer EXT when we had it had issues when it was cool out she would pull out of the driveway and the gas pedal would go t the floor RPM's would go not nothing and the truck would not go faster than 10-15mph. After a minute or so and it warmed it was fine.

We took it in dealership said nothing was wrong, I ended up trading it in back in October for a Suburban. Last week I had to get a tail light replaced on my Silverado when the tech who always works on my vehicles said our old Trailblazer was in the shop for two weeks. Apparently one of the pistons was bad it some how caused the gasket or seal to break knocking out the temp sensor the engine ended up overheating and seizing. The dealership said a crack was found in the block causing some issues with pressure thus the new owners had to pony up $7k for a new engine, parts and labor. The SUV was out of warranty with 43k on her.

Good luck