I'm using the EMP-34 pickup to detect the bolts on the propshaft (the version with three wires, +12, GND and signal - with the orange LED in the top).

All working fine and then the LED is now permanently on and no speed reading - It could of course just be bust but I'm wondering, could it magnitise? Could I have over-volted it as I'm not sure that my alternator is correctly wired back (but it seems OK)?

This is now the third speedo sender that's gone kaput; tried hall effect twice(useless) and this one seemed better. Is the only robust solution an optical sensor?...

Thoughts observations and general wisdom much appreciated... I've got to nip out now but I'll look in this afternoon.

try a inductive one, they are better quality...

i use a siemens one of 50€...