6. Cylinder duster is now a 340 ignition issues wants to start when you let up on the key

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flathead31coupe

flathead31coupe

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I've done some research on this. Still can't find what was actually the problem when people had this issue. With a test light hooked up to the ballast resistor I turn the key on. I have light when I turn it to start. I have no light.. so I went to my ignition plug on the column and found that the yellow wire has power when I am in to start position as I believe it should also the yellow wire comes through the bulkhead all the way upper top right hand position. Just trying to figure out how to make it work like it should. Any help would be appreciated
 
flathead31coupe said:
I've done some research on this. Still can't find what was actually the problem when people had this issue. With a test light hooked up to the ballast resistor I turn the key on. I have light when I turn it to start. I have no light.. so I went to my ignition plug on the column and found that the yellow wire has power when I am in to start position as I believe it should also the yellow wire comes through the bulkhead all the way upper top right hand position. Just trying to figure out how to make it work like it should. Any help would be appreciated
Click to expand...
So is there voltage on that side of the bulkhead when you turn the key to start sounds like you figured it out or am I missing something?
 
Sorry for being confusing. I have power to the existing ballast when not cranking but in the run position. And I have power when cranking on the yellow wire that comes from the ignition through the bulkhead in the upper right hand far right corner of the bulkhead but I don't know where it's supposed to go. I've traced it over to look like the horny lay for some reason somebody did the wiring before I got it said that they always had trouble with it starting when they let up on the ignition switch . It also only has a single ballast instead of the dual ballast that it probably came with, so I'm not sure of where the wiring should be. Of course it has electronic distributor. I just don't know if I can make it work with a single ballast or have to hook the dual ballast back up. I found this picture and it looks to me like I can just hook that yellow wire that is hot when I'm cranking it the side of the ballast that goes to the side of the coil and it would work but I'm not sure

Screenshot_20230705-151302.png
 
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You have to understand how Mopar ignition works

1....First, there is only one 12V switched source into the engine bay with the key in "run". This is the (unfused) IGN1 "ignition run" power comeing out of the bulkhead connector into the bay. This splits up, and feeds the VR, the ignition system (ballast), the alternator (blue) field 70 and later, and depending on year/ model, electric choke if used, and some smog doo dads in later years.

IT IS NORMAL for that power to go dead in START

2...So how does it start? The ignition switch has TWO switch contacts (2 circuits) that are momentary hot when the key is in "start." One, of course, is the usual (usually yellow) "start" wire, and the 2nd is the ballast bypass circuit, IGN2, usually brown. This only goes one place---from the key switch, out through the bulkhead connector, and to the coil + side of the ballast. It is hot whenever "start" is hot, and IS the power that starts the car

IF YOU have modified the wiring, added aftermarket ignition, eliminated the ballast, etc, check that this brown is incorporated into the new power to the ignition.
 
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The single ballast has nothing to do with this. Either points, Mopar 4 wire ballast, or Mopar 2 wire ballast/ electronic, that part is always wired the same. The brown bypass always goes to the coil + terminal on the ballast resistor.
 
Thanks a lot. I will check that out All I can tell you for sure is I have power to the ballast when I turn the key on. That's it. So I have a wire I have to find
 
So after looking at it again, it looks like they've relocated the ignition box from the driver side to the passenger side looks like they left everything hooked up and just tied on to the new electric ignition box wiring harness. I need to sort it all out if I want to put it back where it goes originally or.

PXL_20230705_221118058.jpg


PXL_20230705_221243350.jpg


PXL_20230705_221250302.jpg
 
Does anyone have a picture or a diagram of where the factory starter relay? ECU the box for the alternator and the ballast go on a factory 75 duster
 
Is this plug in harness? A factory piece looks like it hooks up to the temperature sanding unit and the alternator and a few other things. I'm only asking because I have no idea of what's supposed to be here

PXL_20230706_002312188.jpg
 
flathead31coupe said:
So after looking at it again, it looks like they've relocated the ignition box from the driver side to the passenger side looks like they left everything hooked up and just tied on to the new electric ignition box wiring harness. I need to sort it all out if I want to put it back where it goes originally or.

View attachment 1716110898

View attachment 1716110899

View attachment 1716110900
Click to expand...
Sounds like a good move.


I have a few pics of @zkx14 '75 if I can find 'em
 
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At the moment the only one I can find is this one. I know I have a couple more, but not sure where I filed them.
1688605959741.png



Some have reported early '75s with seat belt interlock.

As best I can tell, the majority of '75 cars did not.
However they did split the alternator's output power before going through the bulkhead connector.
The power feed to the key switch gets its a fusible link, in addition to the normal fusible link on the battery feed.
1688606569744.png

Open circles and squares represent connectors.
Solid circles represent welded spices.
Yellow was often used to identify the wire from the key switch to the starter relay.


This may be the 'engine connector'
1688606864026.png


There's a partial diagram from a '75 service manual here.
 
@Bugman posted this in another thread.
1688607394235.png

Position Z is J1 (power to key switch) an 18 gage Gray with red stripe fusible link. This is connected to both the battery and the alternator. ie. Its always hot.
Position L is S2 (starter relay from key switch) 18 gage yellow. This should have power when the key is in start.
Position Q is J3 (ignition start from key switch) 14 gage brown. This should have power when the key is in start.

1688607776212.png
 
Thanks a lot. I appreciate it. Mine looks like it has the interlock switch with the reset button on it. Two yellow wires, one yellow with a black stripe and a different color wire. Also, where did the alternator regulator mount? Thanks
 
You may also be able ot test on the inside.
The position letters are molded in the plastic.
1688607916896.png
 
The 1/2 ohm resistor is needed to protect the coil when the engine is running.
A newer ECU will not need the 5 ohm resistor. Having it there won't hurt, its just not needed.
The top pin of the ECU is the power connection. Wire J2D in the drawing. That connection is needed.
1688608325994.png



A place to buy a paper manual

1975 CHRYSLER, DODGE, PLYMOUTH Full Line Body, Chassis & Electrical Service Manual

automotive repair manual, service manuals, owners manual, waxes, cleaners, sale brochure, parts book
www.autobooksbishko.com
 
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Yeh you need to get a manual, digi or paper. Wiring in these girls changed almost every year from 71--75 or 6 so be careful what you are looking at.

Frankly if it is wired correctly, I see no reason to relocate it.
 
Well I have the starting issue that only wants to run when you let off the key. So I think whoever installed the new ECU and wiring harness didn't install the wire from the starter that was needed. After investigating and untaping a realize that the original wine harness for the four wire, ballast and ECU is still there, they just tapped into the wiring. I was just trying to clean out the wire in a little bit. They mounted the new ECU on the passenger fender with the voter regulator in the original ECU wiring and ballast wiring is on the driver side is still there so I'm trying to figure out which to do
 
Be nice to get it figured out, make good connections, then wrap them into a harness and get them secured. All it takes is one bad connection or one wire scraping against something to ruin the fun.
Some people like the convolute wire loom better. To me the tape is more compact but takes more work (a little).

67Dart273 posted a neat splice
www.forabodiesonly.com

Inline wiring splice clips........from the Dodge RAM service manual

!!HUH!! Old man learned something. Was into the Dodge ram service manual and saw a little drawing about inline splice "clips" A simple little "U" shaped clip that you wrap around the "running" wire along with the "to be added" tap wire, and crimp. Solder........Makes a...
www.forabodiesonly.com www.forabodiesonly.com
 
Does anyone know where the stock starter relay location is on a 75 Plymouth duster. I thought it would be close to the battery tray but I see no holes but I do see a little bump and a couple hoes up on the driver side firewall that looks like it could have been mounted there at one time
 
Your car's starter relay is in the correct postion.
Maybe or maybe not the correct orientation.
Your car was manufactured with the seatbelt interlock, and still has the bypass switch.
1688677073759.png


You may find additional parts of the system on the car.

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1688677199764.png

from the 1974 Booklet explaining the system

Browse MTSC by Model Year – 1974 – MyMopar

mymopar.com mymopar.com


That may be why the J3 wire isn't getting power with key in start. Eitehr the system failed, or it wasn't properly disconnected/bypassed.
See the posts here about the early '75 versions from @Bugman and @67Dart273
www.forabodiesonly.com

Continuing to track down source of no voltage to coil while cranking

Car I'm working on is a 75 Duster 360. (5 wire ECU w/ Dual Ballast) It has an intermittent issue that'll cause it to crank and them immediately fire off when the key returns to the run position. Yesterday I replaced the ignition switch and hoped that it would solve it as it was the last...
www.forabodiesonly.com www.forabodiesonly.com

Those are the guys that can help you bypass that thing properly.
 
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flathead31coupe said:
I'm sorry I meant to votltege regulator for the alternator
Click to expand...
Yours is close to the correct spot.
Wire routing doesn't look right.

I can't find my photos of @zkx14 engine bay. But a search for 1975 here may turn up some photos.
 
Thank you so much! I really appreciate it. I just want it back like it was supposed to be. Do we know what color wires go to the coil factory?
 
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