Ignition 1 and 2

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scatpakman

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I'm a little confused when it comes to wiring diagrams. Looking the diagram in my service manual, I see ignition 1 and ignition 2. Am I wrong in assuming they (1 and 2) are for Start and Run. If so, which is which?
 
IGN1 is "run" but it is ONLY hot in "run." That is it goes dead with key in "start." This wire feeds ignition system, alternator field (70/ later) and VR, and electric choke if used, and other smog doo dads on some years/ models

IGN2 (brown) is the resistor bypass circuit and is hot ONLY in start. It is the ONLY source of ignition voltage in "start." If you run an aftermarket ignition system that does not use a ballast resistor, you much jumper IGN1 and IGN2 together
 
IGN1 is "run" but it is ONLY hot in "run." That is it goes dead with key in "start." This wire feeds ignition system, alternator field (70/ later) and VR, and electric choke if used, and other smog doo dads on some years/ models

IGN2 (brown) is the resistor bypass circuit and is hot ONLY in start. It is the ONLY source of ignition voltage in "start." If you run an aftermarket ignition system that does not use a ballast resistor, you much jumper IGN1 and IGN2 together

20200719_160203.jpg
 
So in this instant, the 2 red wires from the MSD and distributor are spliced together and joined by Ignition 1 and Ignition 2???
 
Yeh, only "it gets more complicated" and here is why

In theory you can splice IGN1 and IGN2 together at the ballast. Don't leave out any spliced wires in that connection, like the one going off to the VR. Now you can take your original coil + wire and use that to feed the two reds in the diagram That "in theory" would work fine

HOWEVER........The complication is, that most of these old girls have voltage drop in that circuit which causes low voltage when starting or low idle RPM and ALSO CAUSES high charging voltage because the low voltage to the VR causes it to over charge

HOW TO FIX

One way is to electrcially cut the blue ign1 "run" wire coming out into the engine bay, near the bulkhead connector. Use the wire from the bulkhead connector to trigger a relay. Feed the relay contacts through a big fuse/ breaker say 20-30A from the "big stud" on the starter relay

take the engine bay end of the cut blue and connect that to the load contacts of the relay. Now the various underhood stuff is fed right off the relay and gets full voltage

You can tell if you have over-charge voltage, caused by harness voltage drop in a couple / three ways. One is to monitor battery "running" voltage. If it gets above 14 by much you likely have this problem

Or turn key to "run" with engine stopped. Put one meter probe on the "key side" of the ballast and stab the other into battery + post. You should see very little voltage, over .3V or more you have a drop problem

This is normally caused by poor connections in the bulkhead connector, at the ignition switch connector, or in the switch contacts themselves
 
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