I am going to install an aftermarkt tach in my truck and dont know where the best and easiest place to intall it is...
Should I hood it to the neg coil? Crank sensor? PCM?
I tried to search the forum but no one has any real soild info...
BTW-91 f150 4.9L 5speed...
Thanks to all that help!

 

Coil (-)
There should also be a wire from the PCM but it is just spliced to the coil (-) anyway so why bother cutting into the harness

 

got mine hooked into the - of the coil if i remember corectly its the green with yellow stripe

 

losthillbilly-any chance you can get a pic of it for me?
I am trying to get a referene point...

 

in this one u can see both wires commin from the coil red "hot" green and yellow strip "ground"



in this one u can see i used a splice conector like what u use when hooking up a trailor harness



my tach had 4 wires red "hot" black "ground" white "light" green "to coil"

i hooked the red to the empty costant hot in my fuse block i grounded the ground to the e-break braket and i hooked the light into the dash light so when u turn the lights on the tach light comes on



in this one u can see ware i mounted my tach its out of the way but still easly seen plus it was easy to hide the wires going down into the kick pannel

also when u do this use a razor blade to cut the tape off the case on the coil wires but becarfull not to nick the wires

 

All the wiring needed for the tach is in the instrument cluster connectors. There's no need to pull wires thru the firewall. So the BEST place for a tach is IN THE CLUSTER - just find one in the JY and swap it in.



It's simple to open them up & swap the speedo so you keep your original odometer.

 

Thanks losthillbilly, that should work great for me!
Steve83, I got the tach as a present for my bday thats why I am just hooking this one up. Plus I like the look of an aftermarket tach! lol

 

You should still use the wiring in the cluster connectors to hook it up.

 

This can be done?
Which is harder? To pull the dash off and plug it in via the cluster or to just run it through the firewall into the - coil?

 

Depends on your definition of "harder". I'd rather sit in the seat & take out a few screws instead of lying upside-down in the floor & shoving wires through a grommet.

 

Good point...I am waiting on a chiltons but how many screws are we talking about? Even then Do I have to run any wires through the firewall? If I could just plug and go I would rather do that.

 

A clip each for the h/l & wiper *****, a few screws for the cluster bezel, unplug the tank & other switches (if equipped), pull 2 screws & drop the shift indicator (if equipped); 4 screws, 2 connectors, & the speedo cable, and the cluster comes out. At that point, you can either splice the tach into the cluster wiring, or just plug in a tach cluster, then put it all back in.