JScan Tire Size Issues [Help]

huntb

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I changed my tire size using JScan and then the dealer must have flashed over it when they reprogrammed my radio. I thought it just reset it and I would need to reprogram them again, but now the speedo is ~3% fast, which would mean the computer thinks the tires are larger than what they are, not back to stock.

Does anyone know how to reset everything back to stock so I can reprogram to the correct size?





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Stuckinthesand

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You have to select the stock tire size. It says 31.25 factory in the app.
 
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huntb

huntb

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Resetting it back to stock got it close to what it should be, but it is still off. I'm asking if there is a way to reset the module, where tire size information is stored, back to default.
 

Stuckinthesand

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As far as I know there is now way to reset it back to default with JScan. You can try to do an ecu reset and that may work. I’m a little confused. Are you running stock tires or larger tires?
 
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huntb

huntb

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As far as I know there is now way to reset it back to default with JScan. You can try to do an ecu reset and that may work. I’m a little confused. Are you running stock tires or larger tires?
I'm running rubi take offs on my Sahara and programmed it with JScan to correct for the larger tires. I then had some dealer work done because my UConnect was acting up without changing the tires back to stock. They must have overwritten something because the speedo was acting like there were 34 or 35's on when I got it back. JScan still showed the 32.5" that I had set it with. I changed it back to the stock 31.25 with JScan and it helped, but the speedo is still slightly off
 

Stuckinthesand

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I'm running rubi take offs on my Sahara and programmed it with JScan to correct for the larger tires. I then had some dealer work done because my UConnect was acting up without changing the tires back to stock. They must have overwritten something because the speedo was acting like there were 34 or 35's on when I got it back. JScan still showed the 32.5" that I had set it with. I changed it back to the stock 31.25 with JScan and it helped, but the speedo is still slightly off
Ok now I understand. That’s weird. I know even though I’m running 35’s I had to set the tire size to 33.5 with JScan to get my speedo dead on. Maybe take it down one more size to see if it gets the speedo correct. I have an auto and even though it’s programmed at 33.5 it still shifts gears like normal. Only other thing I can think of is to disconnect the batteries or pull the ecu fuses to reset it.
 
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huntb

huntb

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Ok now I understand. That’s weird. I know even though I’m running 35’s I had to set the tire size to 33.5 with JScan to get my speedo dead on. Maybe take it down one more size to see if it gets the speedo correct. I have an auto and even though it’s programmed at 33.5 it still shifts gears like normal. Only other thing I can think of is to disconnect the batteries or pull the ecu fuses to reset it.
Good to know, thanks. I'll give your suggestions a try and report back. The dealer also didn't fix my radio issues either, so I plan on taking it back and will have it reset to stock before I go
 

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