speedo stopped
 

My speedo (930) has stopped. For no obvious reason.
Am I able to check a voltage output from the gearbox drive unit?
The wire codes from the gear linkage terminal to the speedo are the same for both wires. Does it matter which one is hooked to the wires from the drive unit - which are clour coded different - green and brown.
Bit lost where to look. The wires are intact on back of speedo.
Thanks
Alan

There is a connection of the wires in the rear plate of the tunnel, to the passanger side
Its possible to have the sending unit go bad and its possible to have the magnets fall off the disc in the trans.
Bruce

How would I check if the sender unit is faulty, or the magnets fallen off in g/box?
Presumably there is a voltage I can check at the terminals in the gear linkage housing?
Alan

I dont know how to check it because there is so few parts that can fail that I just put another one in place. except for the magnets inside they would only fail one at a time and I think there is 8. I had 3 magnets off on one trans and it would read slower..3/8ths slower.
To check the pickup you would need to create a magnetic field for it.
Bruce

My car is up on jackstands at moment (engine partly disassembled).
I was wondering if I could run it in gear, and measure something at the terminals in the trans tunnel.
But I dont know what I should be looking for voltage wise - AC/DC. how much?
If the magnets fall off in the trans case, that might be problematic?
Alan