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2000 Silverado Z71 4x4 5.3L 460k+ miles w/ GM rebuilt motor and trans
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Have you had the computer tuned to the appropriate tire size and rear end gearing? Sounds like a programming issue...
 

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If the stepper motor is good, the rear end gears are what the truck came with, and the tires are the size that came on the truck, or at least are the same height is the same as the original size tires, and the speedometer is still off, then it can be reset in the ECM. I have reset mine with a hand held, Jet programer that I bought to tune my truck. This allows me to adjust things like tire size, gear ratio, and a whole lot more. You may be able to get a local transmission shop to reset it for you, or a dyno shop that tunes vehicles, or even a good repair shop may be able to do this. My programer sales for about $325 and is or was available on Summit racing. You would need to go to www.summitracing.com
 

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Nothing on it has been changed, correct tiresize, everything is original, when I use my code reader to see my speed it's correct
So your code reader is telling you that everything before the speedo is correct, meaning, the speedos calibration is off. There is no way to set this your self. The repair shops that work on clusters have tooling for this, but very few will work on 96-98 clusters. The simple answer is to reset you tire size to get the speedo to read correctly, but you have to be careful with that because the transmission shifts by reading MPH.
 

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Not sure about your ground. Maybe so, IDK. Ether one of these will let you adjust for tire size, ect. Go on summits site and look at them. The top one is what I have. The bottom one, needs a lap top, but you can set more things with it.
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My 1996 chevy c1500 has the speedometer 12 off 40 mph if 50 on the dash and 57 mph is 70 on the dash iv heard it's common issue and I'm running on 235/75/r15 and the computer says I have a 3:12 rear end
 

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My 1996 chevy c1500 has the speedometer 12 off 40 mph if 50 on the dash and 57 mph is 70 on the dash iv heard it's common issue and I'm running on 235/75/r15 and the computer says I have a 3:12 rear end
3.12??? Hummm. Not sure about that. 3.08, or 3.23,or 3.42, or 3.73. tell you what though, there is a way to find out for sure. Follow this video. It doesnt matter that the truck is a S-10. Its the same process.
 

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It did have 205/75r15 when my grandpa got it but he went with the 235/75r15 so it's possible that someone programed the pcm for it because my rpm gage reads 500 rpm more than it should at 57 the dash says 2000 my code reader says 1500 and none of my gages read right except for the water and battery the oil pressure reads what it wants
 

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It did have 205/75r15 when my grandpa got it but he went with the 235/75r15 so it's possible that someone programed the pcm for it because my rpm gage reads 500 rpm more than it should at 57 the dash says 2000 my code reader says 1500 and none of my gages read right except for the water and battery the oil pressure reads what it wants
That sounds like cluster problems, but IDK. Could be someone programmed the ECM but, there is no real way ti be sure without the original programmer that would have reset everything. Could be a ground issue as well. Aslo may be something wrong with the printed circuit board. You may want to get a cluster from the junk yard and try that.
 

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98 gmc k1500 5.7
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why is it i cannot see the original question here , or anything else he says, i see all the responses , but not the question
 

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well, I'm guna make a guess here.... the OP didn't like something in the thread... no idea how or what because it's all gone. so since we cant delete our own content they replaced it with a 1.

ya I dont get it either.
 
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nope you are sane! haha

I had all the same questions the other day.... wondering what was up.

Meh.... guess it wasnt that important.

Al
 

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All the content was deleted by the OP. Since there were replies, he couldn't remove the thread. All he could do was put a one character symbol in the place of his words.
 
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