Sign in to follow this  
Guest Anonymous

Help needed with ignition coil and starter wiring

11 posts in this topic Last Reply

Recommended Posts

Guest Anonymous

Okay, so I've finally got the '74 Auto back running after replacing the starter motor and the section of shorted out ignition wire. I incorrectly reported earlier that I had the red Bosch coil but in fact I have just a plain black coil with no resistor. Here are the questions:

1. What wires go into the ignition coil? I have a pair of wires that share a female spade connector going into the positive. One of those is the green wire from the ignition and the other is a black (or some other color covered by dirt) and red wire that seems to go all the way to a spade connector near the starter motor. That dirt and red wire turned out to be my problem because it really doesn't like being connected to the starter motor though I could have sworn it came off of there. On the negative side of the coil I have a black wire to the distributor and and a black wire to the tach.

2. What wires go into the starter motor/solenoid? I have the big positive lead hooked up and then a two-wire-sharing-one-female-spade-connector combo going into the positive trigger side of the solenoid. There's one remaining spade connector on the assembly that looks like it wants a wire connected to it. Through trial and error I've discovered that the conveniently placed dirt and red colored wire that comes from the positive terminal of the ignition coil is definitely not what should be hooked up there...

Thanks everyone for the help. I wish I actually had a complete wiring diagram that covered all the crap under the hood of a '74 Automatic. The closest I can find in the Haynes manual is to use the 2000 Touring wiring diagram but even that only shows two total wires connecting to the starter motor.

Share this post


Link to post
Share on other sites
Guest Anonymous

diagram.jpg

i dont have an auto or any experience with one, but a friend lent me this when i was getting my tii wiring all sorted out:

Share this post


Link to post
Share on other sites
Guest Anonymous

There should be a 12v source which is the green wire to the + side of the coil. Then there are two that go to the - side. One from the condensor on the dizzy and the second on from the tach. those are the only three wires that need to be connected. If you have an electric choke, or an Idle cutoff solinoid there might be a wire from the + side to that.

HTH

Andy Rattley

Share this post


Link to post
Share on other sites
Guest Anonymous

That's a great looking wiring diagram but it doesn't help me any more than what I already have. I need a complete wiring diagram for a '74 which is 12 fuses and has all kinds of extra crazy junk. Thanks anyway.

Share this post


Link to post
Share on other sites
Guest Anonymous

If the green wire to coil terminal 15 is a normal copper wire, that is your problem. It should be a resistance wire of about one ohm; it serves as the ballast resistor. Is that the section of "ignition wire" you replaced? If it is normal wire and you can't find resistance wire to replace it, you can add a normal ballast resistor between the green wire and coil terminal 15.

A black/red (dirt/red?) wire should run from coil terminal 15 to starter terminal 15. (This wire gets full battery voltage from the starter during cranking, and gives it to the coil, bypasssing the ballast resistance.) If you add a ballast resistor as described above, the black/red wire still goes to coil terminal 15.

If you run the wires according to the above and still have a problem, there is something else wrong with the wiring. Since you replaced the starter, that is not likely the problem. Email me for further troubleshooting instructions.

The two black wires on coil terminal 1 (neg) are correct.

There should be one or two black/white wires on starter terminal 50 (trigger).

The coil wiring is the same for red or black coils.

Share this post


Link to post
Share on other sites
Guest Anonymous

Curt,

How do I tell which is terminal 15 on the starter? A wire from the starter to the ignition coil that supplies 12v during starting would totally explain the dirt/red wire going from the starter to positive side of the coil. I may get out there and hook up a multimeter and try cranking her over to figure out if the terminal on the starter that I think you are talking about kicks out 12v under starting conditions.

Also, what purpose does the balast resistor or resistor wire serve on the ignition circuit? Do you have any specs on the resistor so I can pick it up from the local electrical supply house instead of waiting for one to come in the mail? By the way, the car does manage to start fine with the ignition wire straight into the positive coil terminal and no connection between the starter and the positive coil terminal. Tempting to just leave it this way but I'm sure you are going to tell me that I'll soon fry my coil...

Share this post


Link to post
Share on other sites
Guest Anonymous

The car has the standard solex carb in it. I don't think that has an electric choke and I have no idea if that would have a idle cutoff solenoid. If it does, where would the connector be?

Share this post


Link to post
Share on other sites
Guest Anonymous

Look at the pass side of the carb. If there is a big cylinder sticking out from the side of the carb that has a spade connector on it, that is the vlave. If its just the stock solex, I doubt you will have one.

Andy

Share this post


Link to post
Share on other sites
Guest Anonymous

my wife wont let me paint that as a mural on the livingroom wall

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this