1999 seville speedometer issues

[baleibec]

hey everyone, im new to the forum and tried to search the post to see if anyone has reported the problem that im having, but have not found the answer just yet, hopefully ya can help me on this. my 1999 seville speedometer fluctuates alot durring normal driving, sometimes readinf a steddy 120 while only doing 55(mph). any help?

[JimD]

It would help us if you would retrieve/display/report any Diagnostic Touble Codes.

Here's how to do that;

http://www.caddyinfo.com/readingcodes.html

[Bruce Nunnally]

too

There was a technote specific to the 99 Seville:

Important

Prior to performing any mechanical repair, it is imperative to confirm that the output speed sensor circuit is functioning normally and that the condition is not a malfunction in the speed sensor or cruise control system or wiring. Specifically, inspect the wiring harness connector at the vehicle speed sensor. The vehicle harness may be installed such that the harness exhibits excessive tension, causing a poor connection at the vehicle speed sensor. This condition may also be caused by air gap variation between the speed sensor (130) and the differential carrier (110) due to movement of the final drive internal gear (120) relative to the transmission case. This causes wear of the bushing (124) in the case extension (134). Some affected transmissions may have a mis-machined final drive internal gear outside diameter and has a final drive internal gear retaining ring (135A) with a corner break at the thickest side. Some vehicles with the 3.11 or the 3.71 final drive ratio carrier assembly (100) may also have one or more planet pinions (103) with mis-machined gear teeth.

Otherwise you want to check the circuit from the PCM to the VSS.

[Logan]

It's either the VSS sensor, wiring, or a IPC issue.

My money is on the VSS sensor. Easy to change, above passenger side trans where the axle inserts into the trans.

Havent seen Bruces TSB, guess I'll take a look at that one. Cant know them all...