How-to: 1990 Ford Mustang 5.0l RPM tach. - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

**djzx3** · 03-29-2011, 12:06

This is a How-to:, to show you how I installed a new AutoMeter 5" Tachometer with optional Shift Light on my 1990 Ford mustang 5.0l V8. I went with the Phantom II Series because I love the all matte black housing and the difference in night and day illumination. I'm not sure if AutoMeter makes one already but if they don't, an all matte black mounting bezel would really be a nice touch for this series.

I first needed to figure out how to wire this beast in. Being that this was my first Tach install, I was originally going to follow the instructions provided by AutoMeter. Instead I got to thinking that I could somehow utilize the wiring harness that connects the radio. So I went ahead and pulled the radio and found I could do just that.

On the harness I decided to T-Tap into the 12V Ignition/Acc. wire and Chassis Ground wire.

For the Tach's light, I had the option of connecting into the Dimmer wire so the light only comes on when the vehicle lights are on or the Illumination wire. I decided to run the light off the Illumination wire so that the Tach light will always be on.

**djzx3** · 03-29-2011, 12:08

Next I needed to figure out were to run the Tachs coil signal wire to. I pulled the coil cover off the vehcile and found the negative terminal located on the coil plug. For those who may not know, the negative coil wire is tan with a yellow stripe.

Now that I knew where everything would be wired, it was time to figure out where to mount the Tach. As most of you probably guessed, I mounted it on the dash just to the right of the drivers side cluster.

I then drilled a hole in the dash where all the wires would be run and installed a rubber grommet for a clean look.

After fishing all the wires down the drilled hole, I ran the Tachometer's SIGNAL COIL wire (green) through a boot under the driver side dash. Again using a T-Tap connector, I made the connection to the negative coil wire.

Now that the coil wire was taken care of, it was time to run the LIGHT (white), GROUND (black), and POWER (red) wires off the Tach into the radio compartment and make the necessary connections.

With everything connected, it was time to test functionality. Here's a quick video...

After a sigh of relief :) I put the radio back in and hid any exposed wires with black cable cover.

Here's the finished look.

DAY

NIGHT

Thanks to Matt over at Discount Tire Direct, For the great write up, and pic's.