In this instructable I will show you how I installed an aftermarket tachometer on my ‘91 Chevy S-10. Tachometers are a great tool for your vehicle if you enjoy monitoring your engine speed or idle. In fact, they are nearly a necessity for a vehicle with a manual transmission.
Teachers! Did you use this instructable in your classroom?
Add a Teacher Note to share how you incorporated it into your lesson.
Step 1: Parts & Tools
Tachometer - - - - - Can be purchased from most any auto parts store for as low as $33. Mine was salvaged from my old truck
3M quick splice connectors 14-18 gauge - - - - - $4.10 (Walmart)
Automotive diagnostic tool-used for finding tachometer wire
Ratchet and sockets
Step 2: Tachometer Input Wires
The following are the wires going into the tachometer.
Red- ignition power
White- illumination power
Green- tach wire
Step 3: Finding the Tach Wire
First I found the output from the distributor cap. My distributor is hard to get to, so I had to remove a couple wire braces to reach it. Other than being almost out of reach, finding the correct wire was fairly easy.
Step 4: Using the Tach Meter
To be sure I had found the right wire, I used this diagnostic tool. I connected the black wire to the (-) side of the battery and the red to the (+). Next I clipped the meter wire onto the white wire from the distributor. To be sure it was the right one, I had someone watch the meter as I revved the engine.
Be sure to mark or remember the wire for when you come back later.
Next, I found where I wanted to mount the tach, and removed a dash panel to access the wiring behind it. I chose to place the tachometer behind and below the ignition, where it would be out of the way yet I could easily see it.
Note; When I was working on this project, I also installed a new stereo and rewired my instrument panel lights that had not been working.
Step 6: Connecting the Green to the Distributer
I couldn't find anywhere possible to run the wire through the firewall to the distributor, so I drilled my own. Next I ran the wire through the hole to the distributor wire. Luckily the wire was the perfect length. I used a crimp on connector to make the connection easily.
The rest of the wires were connected as follows;
Red--ignition power--from fuse box
Black--ground--cigarette lighter ground
I will not go into detail on how I connected these three wires, because it's pretty basic. The only thing you need to remember is that the wires you tap and their fuses need to be able to support the extra power draw from the tachometer.
Step 8: Finishing Up
Once those connections are made, fire up the engine and make sure it works-mine did. Wrap up all the excess wire and hide it in the dash. Above is a picture of my finished tach. It looks and works great.
Thanks for reading and please feel free to comment