Make a DIY test RPM gauge for under hood diagnostics. RPM mechanic tool.

I had an extra RPM gauge from my old CRX gauge set that I removed and changed for an Integra gauge cluster. So I decided to make this handy mechanics tool.

DIY Mechanics RPM gauge

I start by cutting up a plastic Folgers can (Amazon). I used the bottom half for the gauge connections, and to hold the circuit board.

I plan to have the gauge go through the lid of the coffee can.

I mounted the gauge on with 3 holes in the lid. One for the needle, and 2 for the screws that hold it on.

I then made 3 holes in the bottom for the gauge wiring, and this also holds the circuit board in place.

Everything snaps shut as it should.

Its a nice compact size.

I added hot glue to hold the 2 parts of the plastic can together. Now the lid is as easy to open as it was opening it for coffee.
Then I connected the RPM wires from the gauge to the control board.

I added labels and made a harness with color coded heat shrink.

Easy to use. Connect the big clips to the positive and negative on the battery,
and the little clip goes to the RPM signal wire – from the distributor, or dash harness, or ECU connections.

Here is my first test with it. 1,400 RPM.

4,500 RPM. I also compared it to the gauge in my dash, and they match!