Another ignition issue

[rockymountainspider]

I'm getting no spark from coil. Have 12v when ign is on. Brand new coil. Any suggestions?

[dmwhiteoak]

Did you check the ground ?

[rockymountainspider]

Both terminals show 12v. Is that right?

[digitech]

no, missing ground

[rockymountainspider]

Where does it ground to?

[dmwhiteoak]

There are two terminals on the coil. ( + ) needs 12 v. ( - ) is the ground. It must be grounded.

[majicwrench]

Nope. The (-) side of coil TOGGLES, that is what fires the plugs. You do not have a permanant "ground" on the coil (-)

What type of ignition?? What year??

[rockymountainspider]

1976 point. From a wiring diagram it's says the NEG wire goes to a fuse of some sort then to a relay then back to the distributor. Is that correct?

[spider2081]

Maybe someone has a circuit description for you.
The circuit is very complex.

Yes there is an inline fuse but also there are 2 relays one is called ignition mode relay and the other is called the fuel/ignition mode relay. Also there is a thermal switch in the circuit. It appears to me all of this is between the points in the distributor and the coil - terminal. Question is how do all those components work.
A basic coil and point circuit would have the - coil terminal connected to the ignition points. The terminal would ground through the points when they are closed and no ground when points are open.

Maybe this helps a little

[RoyBatty]

Power flows thru the coils primary circuit to ground when the points are closed.
So yes you can have 12v at both terminals. Positive terminal should be power from the ignition switch. Negative hooks to the points.

[rockymountainspider]

So...I guess I should check the relays. Nothing has been disconnected except for the coil when it was replaced.

[majicwrench]

Why did you replace the coil?? Did it run before you changed the coil? How do you plan to "check" relays?? If it is a point system, the first thing to check is the points!!

[azruss]

yes, check the point gap and the condenser.