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Discussion Starter #1
[SIZE=11pt]Self[/SIZE][SIZE=11pt] Chrysler Grand[/SIZE] Voyager (GS) 3.3 years of production 2000. The vehicle I pmeumatiky 215/65 R15. On summer I put new tires 215/65 R16 and I wanted to change this setting using the DRBIII in TCM. After setting, but the speedometer does not show the correct speed. He thought that a bad TCM. Replaced the TCM but the problem remained.I do not know where the error ?
 

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Welcome to Allpar. How far off is the accuracy? ∓ 5% error is allowable in the USA by law. You have increased the wheel radius by 12.7 mm with the same cross-sectional height of tire.
The difference in radius from the 15" to the 16" wheels is 12.7 mm. Total rim and tire radius has gone from 330.25 mm to 342.95 mm. That is still about a 4% difference and within the allowed error tolerance. I don't think that the instrument cluster itself can be calibrated.
Is it reading faster or slower than actual speed? Is the odometer also off by an equal amount?
 

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I think that if TCM allows the setting should TCM after setting change dimension pneumatilk recalculate and show good speed. If not, according to me are in the engine ECU transmitting invalid data such as vehicle speed, depending on otáčkých engine. This may affect the proper gear shift automatic transmission.
 
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