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BDL
02-06-2008, 03:33 PM
My speedometer has become very erratic. When it fails, it takes the cruise control and odometer with it (great not to add mileage, however). Sometimes it pops right back. Other times, the car needs to sit with engine off for a bit. All the other electronics (normal gauges and computer) are working fine. I drive a '99 M3. Any ideas/suggestions?

WRXEATR
02-06-2008, 05:41 PM
correct me if im wrong, but the Odometer and speedo share a common fuse? at least in my e30 they did. I would look for your fuse, and verify that it is the correct rated fuse.

good luck!

Jscrizil2001
02-06-2008, 08:46 PM
I had the Same PROBLEM!

On the back of ur differential there is a sensor called the speedo meter sender unit.

Check to see if its wires are cut or if the plug is damaged

BDL
02-07-2008, 08:09 PM
Thanks for the tip. A mechanic friend thinks it must be the sender. If it were the main dash display, all the gauges would die, not just the speedo. Do you agree?

Black 840Ci
02-08-2008, 06:04 PM
They are right about the sensor, the guages should work all together or all not!!!

Jscrizil2001
02-12-2008, 07:53 PM
Thanks for the tip. A mechanic friend thinks it must be the sender. If it were the main dash display, all the gauges would die, not just the speedo. Do you agree?



Yes i do agree... wanna make sure its not ur dash.... HOLD UR MILAGE RESET BUTTON ON THE INSTRUMENT CLUSTER... THEN TURN YOUR KEY TO THE ON POSITION....DONT CRANK IT! JUS TURN IT ON... ANd it should start showing you some crazy numbers and such! you will like it!