for those with 124s that have inoperable tachometers, this may help you fix it.

during my previous posts i found out that the tach gets its signal from an engine speed sensor located at the flywheel driver side. its the black plastic module with 2 wires coming out of it, its held there by an allen head bolt. i traced the wire up to a 2 prong connector behind the battery. that connector is connected to the ELR diesel thingy.


anyway, this may help if you want to check your contacts.

in my case, all the contacts were good, it turns out my OVP was to blame. I opened it up to find that 1 contact/switch was corroded. i just cleaned it up using a pin.(clearance is very small)
it,s the contact which gets magnetized, once you remove the cover it's the one that can be accessed easily, the others are almost impossible to reach w/o further disassembly

voila! tach starts working.

or two would be really nice...