transmission not shifting into third or overdrive on 2001 Chevrolet Impala

i just bought a 01 impala, it used to be a police cruiser! the transmission wont go into third or overdrive i just replaced the filter and added new fluid which didnt correct the problem whatsoever, im cluless as to what it might be! the guy i bought it off of said he replaced the transmission before he had to get a transmission from out of state because of it being a police car the gear ratio he said was different from normal 01 impalas!

by in Plymouth, OH on April 11, 2011
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2 answers 1 comment
ANSWER by , June 25, 2011
I had the same issue on my Impala and it turned out to be one of the shifting sensoer located behind the access panel on the left side of the engine. They cost about 30-70 dollars each and their is three sensors in total. Only one needed to be replaced but I suggest you replace them all.
ANSWER by , April 11, 2011
The transmission will need to be removed, disassembled, and repaired to correct the problem. When it comes to automatic transmissions, there are no serviceable parts or systems that can be fixed outside of the case. In either case, the previos owner either didn't install the correct tranny, installed a malfunctioning tranny, or didn't install one at all to begin with and cooked up a good story.
COMMENT by , April 11, 2011
thanks tyreguy i was afraid of that!