I bought an MSD rpm window switch. it has an on at a low rpm and an off at high rpm. I'm trying to hook it up to an LED light right now to see at what rpm it comes on and when it turns off. According to the diagram I can hook up on lead of the light to the yellow wire but where does the other lead of the LED go? to ground or to a 12 volt source? in this diagram the RED is ignition source, WHITE is tach output.
You have to put RPM modules in it to make it operate. You will have to determine what rpm you want it to activate and deactivate and buy the modules.
Doesn't it come on and off depending on the RPM chips? Are you trying to verify that it is working? The yellow wire provides a ground for the SOLENOID/LAMP. Notice the negative symbol [-] on the box? Some LED's are polarized, they required the correct lead attached to a source or drain (ground). Hook up the positive side of the LED to a 12V source and the other side to the yellow wire. Make sure you are using a 12V LED.
ok great, that's what I needed to know. the yellow provides the ground, I need to hook up a power to the other side of the LED. thanks as for the RPM modules, the guy I bought this unit from put together his own potentiometers. They aren't labeled so I'm gonna drive around and figure them out. they look like this
