[Bart]

Today I had a chance to get my Roadster out because of the sunny and warm weather. As I was cruising around 40mph in 4th gear the speedometer needle started fluctuating between the speed I was driving and zero. The needle looked like the tach but was moving much faster bouncing between zero and the speed over and over. This happened throughout the drive. I don't drive this car more than once a week and its 25000 miles attest to that. Any thoughts or ideas on what may be happening. Thanks.

Bart
98 M Roadster

 

[Thrlls]

Same thing happened to me today, except it started happening right when I hit 100 mph It just started bouncing from 100 to 120 back down to 80 or so. I slowed down to 80, and everything was normal :dunno:

 

[JimR]

How SAD.

Your cars seem to have developed that extremely rare (especially in a normal and healthy BMW) psychological malady, Speedometer Anxiety Disorder (SAD). Sufferers from SAD take an inordinate notice of roadside speed limit signs. When they find themselves pushed above the limit, their anxiety causes them to fluctuate wildly in their reporting of road speed.

Honestly? I have no idea. Perhaps I have been reading too many of my wife's social work/psychology journals

jim

 

[dwm]

Today I had a chance to get my Roadster out because of the sunny and warm weather. As I was cruising around 40mph in 4th gear the speedometer needle started fluctuating between the speed I was driving and zero. The needle looked like the tach but was moving much faster bouncing between zero and the speed over and over. This happened throughout the drive. I don't drive this car more than once a week and its 25000 miles attest to that. Any thoughts or ideas on what may be happening. Thanks.

Bart
98 M Roadster

I'd check the connection to the speed sensor. It's plugged into the back of the differential. Could just be corroded contacts on the electrical connection. Could be a failing sensor. With your proximity to the ocean, I suspect corroded contacts.

 

[viper501]

My fuel gauge is having the same problem but only when it is full. Once off 'full', all is well and normal.