kissfans03ss Posted April 13, 2008 Report Share Posted April 13, 2008 Well guys to start off my story i got a ticket Fri. night, the speed was posted for 55 so i did between 60-65 and kept my eye on the needle knowing N.Y. state troopers prowl the are,anyway i come around the corner and there he is at which point i check my speedo...60mph,i pull over and he says i was doing 71mph so today i doble checked and my speedo is off by 10 mph so my question is could a pcm for less tune throw off my speedo or could this be related to the instrument problem that GM on some of our trucks?....for now my truck is stock other than a tune and exhaust. Quote Link to comment Share on other sites More sharing options...
Fireman31 Posted April 13, 2008 Report Share Posted April 13, 2008 Yes it is possible that it is the tune, but it also possible that the cluster is bad.....do you have the factory PCM? If you do, re-install it and check it again. Otherwise, the Tech2 at the dealership should be able to see if there is a difference between the cluster and actual speed........ Quote Link to comment Share on other sites More sharing options...
kissfans03ss Posted April 13, 2008 Author Report Share Posted April 13, 2008 actually i had my original pcm reprogrammed by matt(pladdpezpunk)last year and i done drive the truck enough to really notice a difference in speed,and if i do bring it back to the dealer wont they notice the pcm was changed? Quote Link to comment Share on other sites More sharing options...
dozer Posted April 13, 2008 Report Share Posted April 13, 2008 You can make the changes with HP Tuners. Quote Link to comment Share on other sites More sharing options...
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