Wiring up a tach?

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PanGasket

PanGasket

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I need some help wiring up my tach. I don't know where the wires go. It has 4 wires and I know it has a switch for how many cylinders. I plan on mounting it on my dash and running the wires under the dashpad and through a firewall opening. Any advice or where these wires go?
 
You should have 4 wires 1 green 1 red 1 black and 1 white. The black goes to ground, the red goes to ign. on hot, the green goes to neg coil terminal and the white goes to lights best place to attach is at dimmer switch. Hope that helps.
 
v8fish said:
You should have 4 wires 1 green 1 red 1 black and 1 white. The black goes to ground, the red goes to ign. on hot, the green goes to neg coil terminal and the white goes to lights best place to attach is at dimmer switch. Hope that helps.
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what color is the hot coming off the ign? and whats the best way to splice these wires together in said placed?
 
mine is hooked up to a switched hot coming out of my fusebox. i just took my meter and found a fuse that is only hot when my key is on. its grounded to my dash frame and i run the green through the firewall to my coil.
 
DarTT said:
and which wire on the dimmer switch?
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im not using my tach light so its just not wired in. my fuse panel isnt marked so i dont know which fuse it is, i just searched around until i found one that is only hot with the key.
 
73AbodEE said:
im not using my tach light so its just not wired in. my fuse panel isnt marked so i dont know which fuse it is, i just searched around until i found one that is only hot with the key.
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I guess I'm just gonna have to scavenge my fusebox and experiment on the dimmer switch. I'd think white to white
 
Splicing into "ignition run" is not particularly accessible, and is NOT fused.

So for tach power, get the fuse panel down, and look at the back.

There are TWO buss strips on one side, one is always hot, one is switched. There should be some tabs there where you can attach addionable connectors. You should use an inline fuse but these normally come with huge fuses. You only need 1/2 amp or 1 amp or so fuse

On one end of the panel, is the "inst" fuse. It is completely separate, and one end will have some orange wires. THIS is the dimmer controlled dash lamp output, and is where you need to hook your tach light

Typical panel below: From the left, the first three fuses are "accessory" and therefore switched with the key. This is what you want for tach power

The next two towards the right are "hot."

The fuse to far right is the "inst" fuse, and the bottom, where the orange comes off, is where you want the light hooked to.

18nb76.jpg


Also, when you run the tach wire in from the engine bay, try to "dress" it with ties along ground, such as the column support. This helps shield the wire a little and helps keep radio noise down. Also, is you splice a toggle switch to ground into the tach wire and mount it inconspicuously, you can create an anti--theft switch. Some guys use the cigarette lighter!!! Push in the lighter, hooked only to the tach wire, and no spark!!
 
67Dart273 said:
Splicing into "ignition run" is not particularly accessible, and is NOT fused.

So for tach power, get the fuse panel down, and look at the back.

There are TWO buss strips on one side, one is always hot, one is switched. There should be some tabs there where you can attach addionable connectors. You should use an inline fuse but these normally come with huge fuses. You only need 1/2 amp or 1 amp or so fuse

On one end of the panel, is the "inst" fuse. It is completely separate, and one end will have some orange wires. THIS is the dimmer controlled dash lamp output, and is where you need to hook your tach light

Typical panel below: From the left, the first three fuses are "accessory" and therefore switched with the key. This is what you want for tach power

The next two towards the right are "hot."

The fuse to far right is the "inst" fuse, and the bottom, where the orange comes off, is where you want the light hooked to.

Also, when you run the tach wire in from the engine bay, try to "dress" it with ties along ground, such as the column support. This helps shield the wire a little and helps keep radio noise down. Also, is you splice a toggle switch to ground into the tach wire and mount it inconspicuously, you can create an anti--theft switch. Some guys use the cigarette lighter!!! Push in the lighter, hooked only to the tach wire, and no spark!!
Click to expand...

How does this not fry the coil?
 
Thanks for the info Dart273, your fuse explanation was perfect I was hoping to stumble on some threads on this, now if I can figure out where to mount this thing AND have it look good the one I scored for free is kinda big.
 
Your anti-theft trick. Won't shooting the coil to ground while cranking cause issues with the coil?
 
Not unless you turn the key on and leave it for an extended period, and maybe even THEN it won't. Don't you think the possiblility of a fried coil is a lot better than an empty parking spot?

All the switch does, is the very same thing that the points or Mopar ECU does, IE switches the neg. lead of the coil to ground. If you turned the key on with the points closed, same thing. If you turn the key on with a Mopar ECU, same thing.

Only ignitions that do NOT put current through the coil with key on/ engine off are such things as CD (MSD) and GM HEI modules.

If someone tried to hotwire the car by jumpering a 12v hot lead right to the coil + It MIGHT fry the coil, but in that case they sure as heck are not gonna drive off with it!!!
 
Outkast said:
Thanks for the info Dart273, your fuse explanation was perfect I was hoping to stumble on some threads on this, now if I can figure out where to mount this thing AND have it look good the one I scored for free is kinda big.
Click to expand...

An easy place to mount it is on the drivers side pillar - there is a screw that holds the pillar trim on, just mount it there - you can run the wiring down the side of the dash, and then to the underside of the dash. I did this with my Sunpro Super Tach II with 3 3/8 inch face. That puts it right above the dash pad.

Here it is in the location

September192012

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Green to coil, red to ignition on hot from terminal marked A , black to steering column ground strap location and white to lights. I used the wiring coming out of the terminal marked F. Both of those positions can be referenced off of 67Dart273's image.

If you remove the screw holding the fuse block in, it should tilt down far enough to use female spade terminals that you should solder to the ends of the wires. Run the green wire out of the firewall grommet, and then to the coil.
 
Thanks all! I used my heater/AC switch light. Trying to get the tach wire thru the hole above the steering column. I am doing this on my D100
 
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