Speedometer Failure

When driving home at about 60 mph last night in my 96 Lsi ,I experienced a sudden oscillation of the speedo needle swinging between 20 and 45 mph , even though my road speed hadn't changed .It lasted for about two minutes and then the pointer dropped to zero and wouldn't budge again . I checked the cruise control which then would not operate . About 5 minutes later the "check engine " light came on .
I'll take it to the dealer tomorrow and report back later . I'm not sure if the speedo is cable driven or just an electronic pickup on the SVX .

Alan.

[strange179]

I'm not positive about this but it sounds like one or both of your speed sensors has gone south. I think one of them is inside the transmission, but again I'm not sure. The TCU will store that code and you can retrieve it if you know the procedure. I wish I could be more help but my service manual for the specifics is at home. It definitely sounds like a speed sensor though due to the cruise control being inoperable.
Jay

Jay : thanks for the prompt comments .I checked the dealer today, but the "SVX mechanic " ( they actually do have a guy who knows the SVX pretty well !) is off .So I guess I'll wait until next week .However I'll try your suggestion to read the error codes this weekend .
Thanks again : Alan.

[eddycat2000]

Originally posted by alanscouse
Jay : thanks for the prompt comments .I checked the dealer today, but the "SVX mechanic " ( they actually do have a guy who knows the SVX pretty well !) is off .So I guess I'll wait until next week .However I'll try your suggestion to read the error codes this weekend .
Thanks again : Alan.

It's really easy to pull the sensor and check it yourself. It lives on the right side of the tranny by the diff dipstick tube. Should just take a 17mm open end wrench to crack it loose, and then uscrew by hand.

You may already have the info on why your speedo quit, here's my experience. On the side of the transmission(I believe, I didn't replace mine myself) there is a "device" for lack of the technical name, that acts as an interface between the trans and speedometer or whatever it connects to,(lots of technical info from me today). It's about 2" long and cylindrical. Inside, is a T shaped doohickey, that spins with the trans. speed, relaying vehicle speed to the whatchamacallit. Mine has been replaced, twice, same symptoms you describe.
Mike
P.S. It was the little "T" shaped thingamabob that broke off, the first time it was replaced, the mechanic told me it was a PITA to get the little piece out.