This is a shoutout to Funola (and techguy512), but I'll post it here for all to see.

I was looking for techguy to purchase a new tach computer, but his website is down.

So I went hunting for whatever other information I could find, and I stumbled upon this:



But I was also looking into testing the sensor itself. And I'm now confused as to what type of sensor this may be.

1. Inductive sensors seem to have two wires, and a permanent magnet. They produce a sinusoidal wave, and are tested by measuring the resistance between the two wires;


2. Hall sensors have three wires, and they usually include some circuitry in their housing. These are tested by applying electric power (but not too much) to the power and ground wires, and measuring the voltage change as a magnet passes by. They produce square wave outputs.


Our cars' sensors have 3 wires, but I'm dead sure the tab on the balancer is not magnetic. So our sensors can't be Hall sensors, right? Yet they have 3 wires instead of 2, so they're not inductive sensors either, right? I'm also quite sure they don't have magnetic tips.

Stretch mentions that Funola has done some tests on these sensors with a oscilloscope.

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1995 W202 C250 Diesel, OM605 NA engine, 5-speed manual
1986 W123 200, OM617 NA engine, 5-speed manual, rev counter
1989 W126 300SE, 5-speed manual