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Discussion Starter · #1 · (Edited)
Hello, I was having trouble with my VSS, speedometer was jumping all over and occasionally the O/D light would start flashing so I had my mechanic replace it.

New problem after replacement: the speedometer is reading 15% too fast and the car is shifting erratically especially at high speeds when it goes into overdrive. I had him replace the sensor again but same problem.

The old sensor registered the correct speed when it was working properly which was most of the time but the new ones are way too fast. Any ideas on what the problem could be?

AX4N Transmission & Duratec

Thanks.
 

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Check to make sure hes using the correct vss. Check wiring and plug. Those are classic symptoms of a faulty vss.
 

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Discussion Starter · #3 ·
Do you think an incorrect VSS would work in the car? The speedometer is no longer bouncing around but is just reading too fast and because of this I think I am getting strange shift patterns.
 

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Speed

Check to make sure hes using the correct vss. Check wiring and plug. Those are classic symptoms of a faulty vss.
Likely with 15% that the gear tooth is a few teeth count off. Back in the day, with mechanical speedometers they had different gear tooth count for different applications depending on tire size and rear ax ratio. One tooth is about 4 to 5 %. That is if my memory works.

Always a good idea to compare the old part to the new one. I heard from a Ford mechanic who replaced a half shaft and it had the wrong tooth count for the ABS. They had to take it back out, and pressed the ring off the old one, and the new one and heated the correct count and put it on the new half shaft. "do it right the first time". or "we get it right the second time, most of the time".:D

Have a fine hot weekend.

-chart-
 
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