Tic Toc Tach wiring issues

[ChargerST]

Hi,

My 70 Charger came with a tic toc tach from the factory that is still there. When I bought the car neither the clock nor the tach were working. I tried to follow the wiring and discovered that the tach is probably not hooked up to the coil (I'm not 100% sure because there are 2 wires hooked up to the coil and a black one that is not hooked up - I don't think that there is a splice somewhere in the neg cable that goes to the coil so the one not hooked up should be my tach cable).

Also there are only two cables attached to the back of the tach. A white cable that goes from the spade terminal to the engine bay (probably coil) and a dark blue cable that goes to the fuse box (radio fuse?). As it seems there is no constant 12V source which would explain the non working clock.

I wanna get my tach and clock running again (if they're still working) but I don't wanna fry the tach. Should I just try to hook up the black cable to the coil and see what happens when I start the car?

Here is a picture from the back of the tach:

[71_deputy]

clock is a grey wire different than the tach feed-check with a meter- should be + 12 volts all the time! ) that goes to the headlight switch- same terminal as the pink- which is +12 volts battery feed or some diagarms show it back to the fuse block- still grey wire.

tach- blue wire is ing. power feed-correct- white wire-???  diagrams don't show it.

but look at the terminal beside the other one- with the spacer- that is the terminal for the grey wire from the - coil.

[ChargerST]

Went through the wiring diagram again and as it seems my tach is not correctly hooked up. The white wire you can see in the picture runs to the coil - it should be gray but doesn't matter. The dark blue wire in the picture goes to the fuse box (probably the accessory fuse - according to the diagram).

Here is the mistake: The white/gray wire is hooked up to the wrong stud! it shouldn't be hooked up to the same stud as the accessory wire (dark blue in the picture). The white/gray (coil) wire should be hooked up to the other stud that's not used at the moment..and maybe it will work.

Am I correct with my assumption?


UPDATE:
Found a picture in another thread that confirmed my assumption so I gave it a try, put the grey/white wire on the other stud and hooked it up to the coil. Tried to start but the car wouldn't start - unhooked the wire from the coil and the Charger started right up. Alright, while running I connected the white cable with the coil and the car instantly died. Looks like I don't get a spark when I hook up the tach...I guess the tach is shot, right?

[y3chargerrt]

Which stud are you hooking it up to? Sounds like you might be grounding out the coil when you hook it up.

[FLG]

Yep instant off means your grounding out your coil. Might just be your hooking it up wrong.

[ChargerST]

I used the long stud (which is closer to the "flat" side of the tach housing) for the +12V (dark blue cable going to the fuse box) and hooked up the white/greyish cable (the one that goes to the coil) to the short stud (with the spade terminal).

If you look at the picture I posted earlier you can see that both cables were on the long stud - I don't know why. Somebody has already hacked into the wiring in the past (just by looking at the bulkhead connector) but surprisingly everything except the tach/clock, AC (it was removed) and the key buzzer works.

Here is a picture I used for figuring out how to hook up the wires:



from this thread: http://www.dodgecharger.com/forum/index.php/topic,4240.0.html