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Mid - suggestions?

R

RustyRed

Active Member
Midlife...I bought a tach yesterday to put on the Mustang. Small one that goes on the column.

I need to find a couple of good wires to splice into and since you reworked my underdash harness figured that make you da man.

Tach has four wires in question...two are easy / no brainer.

One needs to go to a wire that is hot when the ignition is in the on position.

Second needs to go to a wire that comes on when the dash lights are on.

The other two are easy....ones a ground and the other goes to the neg side of the coil.

Any suggestions on a good place to splice in on the first two wires?

Just looking for a place to splice in that will be the least interference?
 
Get switched 12V off of the back of the ign. switch? That would be a clean easy option; just solder on a ring terminal and bolt 'er on. I'm not too well acquainted with the dash light wiring on these things anymore, so I'll keep my yap shut on the subject. :lol
 
The lights are easy: they go to a three-prong female bullet connector, red in color with blue/red wires.

The power is more troublesome: you need to patch into the red/green wire coming out of the ignition switch, as that is the only line that is only hot when the key is in RUN but off when key is in ACC. Personally, I would recommend the ACC line which is the post on the back of the ignition switch. So...your tach will be on when the key is in ACC and RUN. Not a big deal for most.
 
I had forgotten about the post on the back of the switch but that will work.

I pretty much never turn the car to Acc...always afraid of frying the petronix.
 
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