1990 Lumina euro - speedometer reads too fast

TOWNSEND11234

MEMBER
1990 ALL OTHER MAKES ALL OTHER MODELS

1990 lumina euro 3.1L V6 - 171,000 miles

cruise control works, vehicle speed sensor replaced with no change to results. Speedometer reads consistently 10 mph fast throughout driving range.

what next? Pcm change?

thanks

3 Replies

DAGRASSCATCHER

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7 POSTS

The incorrect tire size can cause speedomoter fluctuations such as you are referring to.

Meaning a 16 inch rim with a 16 inch factory tire and a 16 inch magnesium wheel with : a 16 inch low profile tire have different heighth measurements.

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Friday, February 2nd, 2007 AT 7:05 PM

CARDUDE28

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13 POSTS

First have a tech drive the car with a scanner hooked up, that way he can monitor the VSS and check it against the speedo. The speedo head may be bad. Could be it needs to be calibrated, it could just be bad. I'd have the speed checked vs the VSS before I pulled the speedo.

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Saturday, February 3rd, 2007 AT 5:26 PM

TOWNSEND11234

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Actually the disparity is not consistent. As the car goes faster the greater disparity. If going 55, it could read 70 to 85. Not jumpy though.

I haven't done anything with this problem. Have read that possibly a bad wire could have an effect like this. The car did sit for a long time before this problem arose.

Thanks for your help!

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Thursday, May 3rd, 2007 AT 8:21 PM