Push button ignition switch help to wire

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Penstarpurist

Penstarpurist

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1973 Plymouth duster 400 big block. Have been trying to make sense of the wiring in our /6 to big block swapped duster. Been using the fsm here on the forum, factory manuals, our parts car reference. And after days of efforts came to finally look under the dash at the fuse block and the hacked in rats nest to see that the fuse block is a lost cause full of rust to where the fuses are becoming one with the unit. Wires cut and hacked. The car is a 4:10 8.75, big block, Mallory unilite,12 point rollcage, ratchet shift car. Came to realize that it's more a drag car than resto. I want to just go with a toggle switch and push button ignition. How should I wire it all with keeping the ballast resistor, neutral safety switch, etc. I would love to keep the turn signals, headlights, running and tailights. But can add that at some point. Any thoughts or suggestions? Thanks.
 
First, none of the start / ignition wiring even goes to the fuse panel

You say you would like to keep turn and lights, etc, this sounds like you are going to drive it.

A few photos might help, you have lots of options depending on your skill, budget, purpose of the build, condition of the old harness, your goals, I mean "it's complicated."

Some options:

You can buy aftermarket fuse panels, or even salvage one out of a later model car

You can pull out the harness and rework it, as completely as you desire, or at least repair it

You can buy "original style" rep harnesses

You can buy generic "budget" so called "11 circuit" or "12 circuit" etc etc "hot rod" harnesses

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Now..........going to a push button might actually be more difficult than you might think...........

This is because the IGNITION SWITCH in a Mopar handles the coil resistor bypass function. This is almost unique in American cars. In GM / Ford the bypass function is done in the starter solenoid

Look at your diagram...........the ignition switch is NOT that hard, what you have:

1.....Main battery feed coming IN to the switch. This is NOT fused other than the fuse link in the engine bay, and comes off the ammeter circuit black wire, the "welded splice."

2....Accessory feed going TO the fuse panel from the IGN switch. This is hot in either ACC or "run." The fuse panel has TWO busses, one hot at all times, the other this ACC feed, and the fuses feed "out" from there

3..."Ignition run" or IGN1. This is hot ONLY in the run position, feeds the instrument cluster, warning lamps, and out through the bulkhead connector, where it branches off and feeds the ignition system (run), the blue alternator field wire, the voltage regulator IGN terminial, some smog doo dads, the electric choke if used

4...."Bypass" or IGN2, usually brown. THIS IS HOT ONLY in start and ONLY has one purpose......it bypasses the coil resistor, and provides ignition power during "crank."

5..."Start" usually yellow. This feeds out through the bulkhead connector to the starter relay, to one of the "flag" "push on" terminals and activates the starter relay if..........

A....the neutral safety switch (automatic)has............ or

B....the clutch safety switch has...........

.........grounded the remaining flag / push on relay terminal
 
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IF YOU USE a push button switch you have a few options:

1....Forget about the bypass circuit but you will have a WEAKER spark during "start"

2....Add a series diode between the "start" wire to the coil + to provide the bypass function

3....Add a relay fired up by the push button, and use that to activate the bypass function.

Bear in mind.............any anti theft..........will be "gone."
 
IF YOU troubleshoot one circuit at a time, post readings as we guide you, and photos, you might be able to fix this in place if it isn't "too bad."

There are several areas of the old Mopar wiring that "could use" some attention. Start by reading the MAD article. I've been chastised for this, but I stick by this. Even if you do not do the bypass as they outline THIS ARTICLE is an excellent overview of "how these work" and what the problems are and why:

Catalog
 
I figured the fuse block had little if anything to do with the ignition beyond dash lights. I have a couple different parts cars from 1971 to '73. As for driving it on the street, it would be like the occasional car show, swap meet. I'd like to be able to keep, repair and use the factory set up whether it be from a donor car or aftermarket. The budget I would prefer to keep cheap, but will spend the money to make it correct.
 
I'l get some pictures and post them for sure. So far the biggest hurdle is it not even turning over, the engine was run in on our break in stand sdo I know it does run. I matched the wiring from the stand into the engine bay, the only difference being obviously the ignition switch is now the one in the car. But I will definitely get several pics and would absolutely be willing to troubleshoot and work with guidance from you guys.
 
Penstarpurist said:
I'l get some pictures and post them for sure. So far the biggest hurdle is it not even turning over, the engine was run in on our break in stand sdo I know it does run. I matched the wiring from the stand into the engine bay, the only difference being obviously the ignition switch is now the one in the car. But I will definitely get several pics and would absolutely be willing to troubleshoot and work with guidance from you guys.
Click to expand...

"Things to check:" cranking

IF you are sure it is a 73 (does not have the seat belt interlock) and is this stick? or automatic?

The "start" (crank) path is.........

ignition switch...........through the bulkhead .........to start relay "flag" or "push on" terminal..........through the starter relay coil.........out the remaining "flag" or push on terminal........and to either the clutch safety switch or automatic, neutral safety switch

Either of these switches are GROUND to operate, IE push the clutch in, the switch grounds the wire.

So check with a light/ meter at the "start" terminal of the relay. Should have battery there with key twisted to "crank."

If so, pull the remaining wire off and clip the remaining relay terminal to ground. Now it should crank.

If not, is the relay bad.
 
Do you have a service manual/ wiring diagrams? If not go over to MyMopar and download them, free. The 73 diagrams are the first year they were "changed" in a major manner. You can get simplified aftermarket "line" drawings over there as well, click on the "wiring" section.

Some of the manuals over there, including the 73, came from the efforts of some of the guys right here
 
It is for sure a '73, automatic, and does have the seat belt light on the dash. The starter relay is new. The neutral safety is grounded, checked that first. I'll check the relay to make sure it isn't bad out of the box. I am going to look for the aftermarket line drawings to verify my wiring hook ups, it well could be that I missed or hooked up something incorrectly. Thanks.
 
Check that you do not have the '74 seat belt interlock. Look for a box under the hood about the size of a horn relay with a big red reset button. "You hope" you won't find it............:

If you do, splice the two yellow wires permanently together

What is this relay for?????

16kx4d2.jpg
 
could you keep the ignition switch and wire a push button in so that you have to turn the key to the "run" position but press the button to start?
 
I would have to retain the column ignition switch to at the very least keep the steering wheel unlocked.
 
dukeboy_318 said:
could you keep the ignition switch and wire a push button in so that you have to turn the key to the "run" position but press the button to start?
Click to expand...

The entire problem as I outlined above boils down to the ballast bypass circuit. Read my first post. A diode, a relay, a different ignition system, or just don't use a bypass circuit and "hope it starts" under adverse conditions.
 
Okay, I looked around and didn' see seatbelt interlock. Here's a few pics of what I did find and the wiring into my starter solenoid.
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It appears the yellow on the start relay is the "start" wire from the key. Start by putting a meter/ test lamp in the rear of that connector, and see if you have power there in "crank." Then move the lamp/ meter to the other push on terminal and see if you have power there in "start." YOU SHOULD NOT. That should be grounded with transmission in park/ neutral
 
It appears the yellow on the start relay is the "start" wire from the key. Start by putting a meter/ test lamp in the rear of that connector, and see if you have power there in "crank." Then move the lamp/ meter to the other push on terminal and see if you have power there in "start." YOU SHOULD NOT. That should be grounded with transmission in park/ neutral
 
I know the neutral ground wire is grounded. That was something we did test already. The yellow wire is the start power wire and when we tested it I'm pretty sure it had power to it. I will go double check it to be sure. Thanks.
 
OK if you have a ground on the dark wire and power on the yellow, it's either the relay, or the fat red going to the solenoid

You can check that fast. Jumper the two exposed terminals on the relay, the big stud and the "square" screw. If it cranks, it's the relay
 
Well, I most definitely owe you a thanks. I So he checked the yellow ignition wire with the key in the crank position. Nada for any volts, so I checked the power at the starter lug, sure enough power. So I supplied the yellow wire directly with power and it cranks over. So they says the starter relay is no good at the very least. I'll pull one off of a parts harness and try that. If it works out I'll grab a new one from the parts store.
 
??? No. The yellow gets power FROM the ignition switch in "crank." The yellow feeds power TO the relay. If the yellow is cold, AND you have the ignition switch in "crank" then it's (no particular order) the ignition switch, bad connection at the switch connector, bad connection at the bulkhead connector, or you made a mistake in measurements.

Keep at it and post back.
 
Yeah, I read again what you had said to test and realized I had tested it wrong. But if I jumper the square pole and and the bug stud it cranks. My sons 71 valiant of course has the same solenoid. And all my wiring matched his, puts out the same test voltage numbers and his car starts and runs all day everyday. I'm really starting to lean towards the possibiliy of it being a bad bulkhead connection or the actual key ignition switch. Either way I'm hopefully narrowing down the culprit. I'm just hoping once I get it to crank over that the rest of it is in working order. Lol.
 
I would double check..........get a solid connection to a test lamp or meter on that yellow right at the start relay. No power when you twist the key? then it's the yellow............through the bulkhead........etc as I outlined. "Wiggle" stuff, the bulkhead connector, and the ignition switch connector.
 
That i will definitely do. Not quite ready to give up on it yet. Thanks again for your help on this.
 
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