I'm not sure if the 2000 Blazer has this same issue, but the 2004 Silverado does. My 2003 Silverado has the same problem.The problem is the small stepper motors in the instrument cluster that move all of the needles (Speedo, tach, gas, temp, etc.). If GM won't fix it for free, and you've exhausted all other avenues, you have some options without paying GM several hundreds of $. If you're handy with a soldering iron, you can fix the speedo for about $12, and the whole cluster for about $75, or you can have someone repair it all for you for about $150. The problem is the same withseveral 2003 to 2007 GM vehicles: most trucks andSUVs, and somecars. See my post in another forum for more details: http://www.topix.net/forum/autos/chevrolet-silverado-1500/TR5QAB2MN19BL1D2J/p8
Mine does the same thing, but its directly related to unhooking the battery.
Get your safety goggles on. Take your negative cable off, make sure the needle is back to zero. If not, tap the negative cable against the post to slightly spark it (BE CAREFUL: batteries can explode) and then see again if the speedo is at zero. If its not, connect the negative cable back to the battery and see if it goes back to zero. Drive it around the block and make sure the speed seems accurate, if you can't tell exactly how accurate it is, have someone follow you. If its not accurate,repeat the process again.
Thanks Blue that did the trick on my 2005 monte having the same problem. Do you know what causes this problem? I would like to have the cause fixed while still under warrenty.. firstname.lastname@example.org
I think what causes it is a normally-closed relay in the gauge pod that sticks open occasionally. I don't think there is any fix to it other than to replace the gauge pod itself and unless the PCM stores the odometer reading, your milage will be reset.
Im having a problem with my speedometer in a 87 s10 4x4 blazer. When its really cold out there is mornings, even after i let it sit for 15-20 min, that it will make a weird sound (not 100% sure how to explain it besides gears grinding really bad) and will be off. Anyone know if i have to actually replace it or is it a simple easy fix???? Also one morning i was going maybe 25 and it was saying i was going 75...it just kept bouncing everywhere........Please help!!