Question:

I have a 1992 Eddie Bauer 2dr 4X4. In the last 4 months I have noticed the following.      - When accelerating, in the 60 to 70 mph range the speedometer would hesitate a little , and then all of a sudden jump to the proper speed. It was as if it was sticking on something. It does not do this consistently.      - The cruise control has developed this habit of surging in the 60 to 70 mph range. It seems to do this for a few moments once the cruise is initially turned on and then settle in and behave normally.      What I am wondering is….. Does the speedometer get its input from the transmission or from some other source such as a  sensor on a wheel. Could the cause of both of the problems be a sensor that is giving an inacurate signal.      If anyone has any ideas or suggestions let me know.      Thanks!  

Response:

>I have a 1992 Eddie Bauer 2dr 4X4. In the last 4 months I have noticed the >following. >     – When accelerating, in the 60 to 70 mph range the speedometer would >hesitate a little , and then all of a sudden jump to the proper speed. It was >as if it was sticking on something. It does not do this consistently. >     – The cruise control has developed this habit of surging in the 60 to 70 >mph range. It seems to do this for a few moments once the cruise is initially >turned on and then settle in and behave normally. >     What I am wondering is….. Does the speedometer get its input from the >transmission or from some other source such as a  sensor on a wheel. Could the >cause of both of the problems be a sensor that is giving an inacurate signal. >     If anyone has any ideas or suggestions let me know. >     Thanks!  

The problems may be related.  The speedometer is driven by a cable that turns in a housing, the cable driven from a small gear ion the transmission.  At the point where the cable attaches to the transmission is a sensor that reads road speed for the engine management computer.  This is the same one that generates the signal for the cruise control. So, what could be wrong?  It’s a tough call.  The gear that drives the cable is pretty tightly coupled to the transmission.  If the cable is sticking in the housing, it will be a bit noisy and cause the speedo to jump around.  But, the CC sensor is at the transmission end, and shouldn’t be affected directly by a sticking cable. Recommendation:  Try lubricating the speedo cable.  Or replace it.  At least one of your problems (speedo jumps) should go away.  If the cable is somehow affecting the CC pickup, it will be cured at the same time. Then you will have cured at least half of your problems, and eliminated a potential problem. A good speedo shop may be the best route to take.  Some other users here have mentioned similar problems, and may offer a better diagnostic method based on their experiences. Good Luck! dr bob

Response:

I have got a similar problem with my 1994 Explorer Sport. I just started noticing it about 2 weeks ago.  I drive steady at about 60-70 mph (checking that the tac stays steady) but my speedometer seems to jump around.  I will glance down, still going the steady speed, and my speedometer will say 80, then jump back to 60, then up to 70, back to 60, up to 75, back to 65, you get the idea? Susan

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