Rockworthy

I know, I know. There are a million posts about this same thing. But the thing is, none of them really tell you how to do it! I have this aftermarket tachometer that I want to use. It's got 4 wires: Red, Black, White, and Green.

White: Dash lighting
Red: Switched 12V
Black: Ground.
Green: Signal wire from tach port, distributor, or "negative side" of the coil.

My problem is with the Green wire. What is the "negative side"? Surely I wouldn't attach the green wire to the big fat wire that goes from the coil to the distributor right? I really don't see where a "negative terminal" is, or how on earth to attach a wire to it. My truck has the EEC-controlled ignition system (TFI-IV).

I know there is a way to swap in a factory tach/speedo gauge cluster and I don't want to do that. I know there is some tach signal wire that is already coming through the firewall in a bundle of wires but who the hell knows how to find that?

snipe1605

If 302 or 351 its the grey wire with yellow stripe coming off the coil. Normally when you buy a tach it comes with a peice of paper telling you what wire. White wire you can wire into the lighting socket for the heater controls, Black ground can be put on the fire wall and redwire you can wire into the fusebox or find a hot wire that only comes on with key on.

jefpel

heres a great writeup

https://www.f150forum.com/f10/afterm...-wiring-19458/

4wheeldevil

out of curiosity why dont you want to do the factory conversion? i did it was very simple and i like where the gauges sit

jaytperry

imo i like the aftermarket tach, i have mine mounted on the a pillar down by the dashboard. eventually i plan on putting more gauges there but will be mounted in a pod. the factory conversion is great if you find a gauge cluster in the proper year. I just like the look though. plus i only paid 30 bucks for mine, and some of the bone yards out there like to take an arm and a leg for parts. rockworthy.. what kind of tach did you purchase?

seprice40

please do not put an aftermarket tach in.....if you really need one buy a stock dash gauge with one built in it, it is plug and play

MattFromKingston

i put an aftermarket one in, one of the little 2 5/8s or whatever inch ones. mounted it at the bottom of my A pillar right behind the registration. i had my door and key in chime disconnected and pulled light and switched right from that. ground went somewhere in there just to a bolt under the dash. my truck is a 300 with the coil mounted on the inner fenderwall and it had the negative right off it for a test port that was a deadplug. see the pic below

Richf150truck

Easiest way is to hook up tach is to tap into the wires going in instrument cluster. Here are the wires you need to find once you open up the dash and get to the the back of the cluster.

Switched power ; RED/YELLOW
Ground; BLACK (or black/white as it was in my truck)
Tach signal; WHITE/PINK
Dash lights; LIGHT BLUE/RED

There all there, easy to get to, clean and you don't have to poke any necessary holes in fire wall.

JIMC93

so your saying my 1993 F150 with a non tach gauge cluster is already equipped to accept a gauge cluster with a tach?No Mods no changes just plug it in???

I visit my local junk yard all the time and i know there is a cluster for a 94 with tach.

jim

4wheeldevil

yes your truck is already wired and no the 94 wont work here is how it breaks down.

92/93
94/95 obdI
95 obdII and 96 obdII

and of course gas engines get gas clusters and diesel engine get diesel clusters. they dont mix.

the reason the cluster match up the way they do is because of the location of the battery light(or lack of). get the wrong cluster and your battery wont charge.

here is my write up on the swap i may do an update to it as i have seen a lot of these threads lately

https://www.f150forum.com/f10/gauge-...p-pics-127758/