speedometer

[emericadna7]

my speedometer wont work 80% of the time and the times that it does work it just jumps to the speed and goes back down repeaditly. how would i fix this

[mdaitc]

try

http://www.unofficialbmw.com/speedo/speedo.htm

when i did mine the other day, i removed the fuel gauge to get better access to the contacts of the plug.

[spiff325is]

you might need a new instrument cluster

[mdaitc]

eh? i had exactly the same problem, figured it was a bad wire because when i pushed on the connector on the back, or jiggled the wires, or hit the panel it fixed it. Then i read the link i showed, which involves re-soldering all the contacts and it was plainly visible they weren't right - dry-jointed. Since i've done that, it's been rock steady. I just wish i did the tach connection when i was in there so my temp gauge might not jump around so much...

[eidelweiss]

How likely is it that the speed sensor can go bad? The reason I ask is that it is a passive device and has no moving parts. I have pulled the boot off that covers the wires to the speed sensor and sprayed with contact cleaner. The conatcts looked clean to begin with. But still no speedometer. I have a perfectly working RPM gauge, but no speedo. With a working RPM Gauge can a fuse still be a culprit?

[WardJ]

rpm is on a seperate cable, so no. i have the same problem now too. my speedometer isn't working all of a sudden

[nukeduster]

actually, the rpm isnt off a cable on e30's. the sensors dont often fail, but the eletrical contacts on the sensors do. they get corroded and send bad signals. clean the contacts on it and plug the 2 wires back on it. that'll fix most e30 speedo problems