98 Taurus with P0500 code

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I have a 98 Taurus station wagon that is getting the code P0500 from the check engine light. That code calls for replacing the vehicle speed sensor. I first bought one from the parts store, installed it and the erratic shifting continued.

We pulled out the new sensor and put the old one back in and the car drove great for about 4 days until the check engine light came on again with the same P0500 code.This time I replaced the old one with a dealer bought sensor, still no luck.

Someone suggested that the problem might be the pcm or turbine speed sensor, so I replaced the tss with a new one and picked up a pcm from the junk yard and tried to install that. The new pcm gave us more errors because it wasn't the same as the original pcm.

Replaced the old pcm and now I am back to the original P0500 code, but after replacing the speed with 3 new sensors I'm pretty sure that the problem is not the speed sensor.

Any suggestions would be greatly appreciated.

[RickMN]

Don't you wish you had checked for a TSB on this condition before buying all these parts and doing all this work? This problem is covered by TSB 01-21-12 and calls for you to replace the ignition switch. Your trouble code is the first code that shows up with a bad ign switch.

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Hi RickMN,

I replaced the ignition switch and the problem persists.

[jram]

i have a 2000 ford ranger that the odmeter jumps around and i replaced the speed sensor and it does the same thing now the odmeter stays on zero

[G O R T]

I suggest a thorough check of the wiring.