How to Install a Tachometer




Introduction: How to Install a Tachometer

About: "CAN'T can't do anything until TRY comes along and does it" -Grandpa

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. 

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)

Wire cutters
Wire strippers
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
Black- ground
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.

Step 5:

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.

Step 7:

The rest of the wires were connected as follows;

Red--ignition power--from fuse box
Black--ground--cigarette lighter ground
White--illumination--headlights/dash lights

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

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    9 years ago on Step 6

    You need to install a rubber grommet where the wire goes through the firewall so it doesn't cause a short. The way you are running it is dangerous it could start a fire if the wire were to short out.


    Reply 1 year ago

    Sorry but there is no way that wire going through the fire wall could cause a fire. It would only short out and blow a fuse.


    Reply 1 year ago

    But a grommet is a must

    william payne
    william payne

    Question 3 years ago on Introduction

    on the back of my tach there are 4 pins for the plug i need to know what color goes on what pin there are letters t l b g i dont know those colors are can you help.


    5 years ago

    hi i need some help i have install a tachometer but my car doest not have distributer it have coils a toyota corona premio


    6 years ago on Step 2

    All we really want to know is where the wires go and it 'd be nice to have that clear up front before looking through all the lovely pics. In fact it is never clearly stated.

    I don't think so anyway. Is it? Main thing is the tacho is connected to the wire from the coil to the distributor. That's it. Right?

    Then it is powered as usual by 12v and an earth. And then it has more power being 12 for the light.

    DIY  Dave
    DIY Dave

    Reply 6 years ago

    I discuss that in steps 2-4. Black, Red and White go straight to the fuse box for ground, ignition power, and light power (connected with the dash lights). The green wire gets crimped to the output from the distributor cap

    Uday nani
    Uday nani

    6 years ago

    Hai i brought a speedometer from kinetic gf 125 bike, i want to install it to my bajaj bike it has 4 wires orange, black, white and yellow plz any body tell me how to connect the wires

    i dont think anyone has mentioned it yet... you should have put a grommet in the hole where cable goes through the firewall.......doubt you would start a fire tho, like some muppet suggested


    9 years ago on Step 6

    You really should add a grommet between the wire and the firewall or else vibrations will cause the firewall to cut the sheathing and make issues later.