Vss problems

[Rob S.]

Looking for advice on vss problems, speedo started to not work intermittently
Changed the sensor got worse, plulled sensor and hooked to drill speedo works fine wire seems ok. What is the sensor bolted to in the trans can that go bad. I can stick my finger in the whole and spin the gear by hand it does have some drag on it. is this normal?

Thanks

[Jeff K]

No. The drive gear on the trans output shaft should be firmly keyed to the output shaft. You should not be able to spin the drive gear on the shaft.

[Rob S.]

not doubting your knowledge but r u sure. just checked it again it seems to free spin in one direction and have drag in the other just wondering if it had like a one way clutch set up or something. If it is the problem after removing the cover is there some thing I should be careful about. I just put another trans in it found a jasper rebuild with 40k on it trans seems to be real good other than the speedo issue screwing up the trans.
Thanks for the info!!!

[Rob S.]

update, I have tried 2 new VSS sensors and speedo still doing the same thing, driving along working fine for a mile or 2 then stops. I Have checked them out of the car using a drill and the speedo would work, cleaned the connector and moved the wire all over the place does not seem to be the problem.
stuck my finger in the whole where the sensor goes to check the gear and felt like i could turn it with my finger but I started the car on jack stands and put it in gear and I could not stop the mating gear on the trans, gear feels ok but cant see it.

I guess my questions at this point would be:
Where does the pcm pick up the signal for the trans, from the speedo or before could the speedo be the problem keeping in mind that the trans downshifts abruptly when the speedo stops.

another point of interest is the whole time we have had the car the speedo has always read 5 mph slower then the actual speed. wondering if related at all.

Any help would be greatly appreciated!!!!

[behlinla]

The PCM reads the speed signal at the VSS. That's what the electrical connector on it is for.

Like Jeff said, you should not be able to spin the gear inside the transmission without the wheels turning. Did you make sure the drive gear on the old sensor didn't come off in the transmission?

Speed difference might be due to wrong-size tires or the speedometer might just be off. You can reposition the needle using GPS as a reference.

[Rob S.]

the gear on the sensor is fine guess i will have to pull the cover of where the sensor goes. any issues to watch for.

[Rob S.]

Update for who ever may have this problem in the future. As it turns out I got 2 bad sensors in a row. Both from Advanced Auto both where BWD brand. After checking every thing else I could I went to Car Quest and ended up buying one with there name on it, not sure who makes it for Car Quest but have been driving the car all afternoon with no problems.
My son was going to University of North Western Ohio for High Performance Automotive and said his teacher all complained about Advanced auto's electrical components having a high failure rate.
Only hear say, either way beware.

[behlinla]

Are you sure you got the right part from AAP? Either way, glad you fixed it.

[Rob S.]

Yea, all three sensors where identical.