E30 Zone

my needle for my speed only works when it wants to (everything else on the speedo clock works fine... rev needle, mpg needle,fuel...etc)... i have noticed sometimes when i hit a bump it will kick back in then when it does work it will suddenly go again. theres no pattern to this...just works when it wants to. connections at back of clock are ok. i have laid down new wiring from the back of the speedo clock all the way to the sensor in the rear diff. straight through wire by passing the junction box under the rear seat. i even put a new sensor in the diff.... what is going on..... im going crazy over this... what else can i test or replace....please help......

Hello mate,

I had the same prob with mine, it pissed me off for months. Tried all the above to no avail. It turned out to be one of the soldered joints on the circuit board (back of speedo) Basically over the years with all the vibrations one of them had cracked, so it kept working intermittently.

Take the instrument panel out and go over all the joints with a soldering iron. You wont need any solder, just reheat whats there and it should give you a good connection again.

I soldered in new batteries on the SI board at the same time, might be worth doing that whilst its out, if they have not been done already...?

Good luck!

cheers for that bogney... will give it a go.... will let you know how i got on

This is quite common, and as bogney says. Look around the pins that plug the speedo board into the main board.
Check the soldered connections to a large resistor near the temp gauge as well while the board is apart, and tighten the two small brass nuts on the back of the cluster.