I'm actually trying to help someone out currently with an issue that seems to be common but that I'm struggling to figure out at the moment. I will not be able to get to the car till Monday but I need some help and info on what I'm about to type here.
This is about a 1973 dart with a slant 6...feel free to move this thread elsewhere if I posted incorrectly.


The issue is when you try to start the car it wont unless you hold the key forward pretty much running it off the starter.
Well I did some googling I found this forum along with some other forums and other people had this issue as well. Common bad things are... bulk head connector which I'm assuming is the one on the firewall with 3 different connectors, ballast resistor, ignition switch, and old wiring. I'm placing my money on old wiring but let me break this down.


With those known issues I did some testing...
At the ballast resistor with the key in the RUN (not starting) position I used a voltmeter hooked a probed to the positive battery post and the other touching each terminal and I got 12volts on each (4 terminal ballast resistor). Im confused on this though?? If Im supposed to have ignition switch 12 volts with the key on run then why would I have to touch the + battery post and not the NEGATIVE? Like if the resistor is grounded.
Same goes for the coil... + and - terminals on coil show 12v when voltmeter probes are placed on battery + and one on either one... I thought they get energized then the coil grounds each time it fires..


Only one that showed 12 volts with probes on battery - and other probe to the blue wire coming from one of the connectors on the firewall (third connector from passenger side, lower left terminal looking at it from the front of the car) hope I'm right on that wire.


Well anyway I got frustrated so I disconnected the negative side of the battery and I disconnected that third bulkhead connector, wire brushed it slighty and the female end then blew off the dirt with compressed air, connected it..and....it worked! I shut it off, started it back up, and again and again. Then... all of a sudden it stopped working. By the way there seems to be an issue with the brake lights because they stay on (probably brake light switch) because the fuse keeps blowing when I move the brake pedal like its shorting.... don't think its related though. However coincidently it stopped working right around the time the fuse blew.... I noticed it after I drove it around before it stopped working. parked it saw the lights then went under the dash to see the switch wiggled the pedal the make contact, saw sparks fly out and then the fuse blew. Tried to start the car but no dice.


So that pissed me off... I couldn't find a diagram that showed the wiring the way the car is wired and for the most part it seems original. So... I pulled the steering wheel off pulled the cam switch off, then got to the ignition switch to trace wires from there. Well I decided to manually operate the ignition switch by pulling it out and turning it and it worked!!
I noticed that when it works, when I put the key to RUN, the orange light which is probably the OIL light but faded comes on then it runs, but if it doesn't it wont stay running. So Im confused cause now this seems intermittent... either that or I fixed it without knowing. Only thing I can say is the red wire coming off the ignition switch was a bit smashed by some black protective plate under the steering column that hides those wires. Im afraid to put it back together and it not work.


Can someone tell me where the blue, red, yellow, brown, black, and double red wires go to? All wires connect to that white connector then the blue one becomes a dark blue with a white stripe and that goes to the fuse block...however, I read that it goes to the bulk head connector????
Which wire supplies power to the fuse block?
And how do I perform a voltage drop test on each wire? Like from what point do I touch the probe to what other point?


Sorry so long, needed to be detailed

 

Here's the problem. ............Wire colors change, and I don't have a '73 shop manual.

Here's a thread "over there" where you can download a 72 shop manual

http://www.forabodiesonly.com/mopar/...p?p=1970088617

and from "MyMopar" is a simplified diagram of the 4 post, 5 pin box

http://www.mymopar.com/index.php?pid=31

go to this page

http://www.mymopar.com/index.php?pid=18

This diagram is electrically correct but may not PHYSICALLY be correct and it does not show the resistor bypass starting circuit. This is a traditionally brown wire which comes off a separate contact in the ignition switch, goes through the bulkhead, and connects to the resistor terminal which feeds the coil + side of the coil

THE REASON that you are getting 12V when the meter is connected to the battery positive is that you are actually NOT getting voltage at the resistor where you are testing. That part of the circuit is actually acting as a GROUND and the battery positive is providing the source. In other words you are getting mislead.

In the diagram below, the top right wire labeled "existing wire" represents the "ignition run" wire coming from the bulkhead. With the key in "run" this should be hot. This goes cold in "start"

With your meter clipped to coil positive, the coil should show "some" low voltage maybe as low as 4--5 volts with the key in "run". If not either the resistor is bad, or you are not getting voltage from the key. You can also check the blue field wire on the alternator.........This should show battery voltage with key in "run."

Again with meter on coil+, and with the key in "start," this should show "same as battery" and in no case less than 10V



Now it is IMPORTANT to understand a few facts................

1.....The original box MUST have a 4 pin resistor that is known as a "5 pin box." LATER ECUs only need 4 pins, and only needed a 2 pin resistor. These later boxes CAN use either an original harness with a 4 pin resistor, or the newer 2 pin resistor. OLDER 5 pin boxes MUST have a 4 pin resistor. To further complicate, not all 4 pin boxes have only 4 pins. Some boxes have 5 physical pins, but the 5th pin is not hooked to anything

2.....There are TWO separate ignition sources, in the manual known as "IGN1" ---used to be traditionally dark blue, otherwise known as "ignition run." This is NOT FUSED at least on earlier cars, and feeds the ignition system, the alternator field (blue), the regulator IGN terminal, and on some cars, things like retard solenoids, idle solenoids, and electric choke if used.

The above, "ign run" goes COLD during crank. It is ONLY HOT with the key in "run."

The SECOND source for ignition is ONLY hot in "start" and is called "IGN2" or the "bypass" circuit. On earlier cars this was traditionally brown, and goes only one place..........from a separate contact on the ignition switch.......to the coil+ side of the ballast resistor.

3......The resistor is TWO separate resistors and is DIFFERENT resistances. Look at the diagram, the "U" shaped cutout in the ceramic. This is what indexes the resistor. See here:

http://www.mymopar.com/index.php?pid=115

Essentially, the part that connects to the coil+ is really no different than the old points resistors. The side which feeds the ECU provides power to part of the box internally

4....Here is a simplified diagram for the later "4 pin" boxes, which CAN use a 2 pin resistor. Notice, compared to the first diagram, that essentially they eliminated the "half" of the resistor which feeds the box. This then was a manufacturing / engineering change to the box

http://www.mymopar.com/downloads/Ign...ystem_4pin.jpg

5....Here is a link to a somewhat better diagram of the system

http://www.mymopar.com/downloads/Dual_Ballast_5pin.pdf

6....Some general checks to this ignition



The ECU MUST be grounded. MUST. Remove it, scrape around the bolt holes, and re--mount using star lock washers. It's not a bad idea to do the same with regulator, and not a bad idea to add no10 or larger ground wires from the ECU/ regulator mounting bolts to the engine

Remove all connectors, the ballast, the ECU, the distributor. Inspect with a light for corrosion, and work in/ out several times to "feel" for tightness.

Especially the distributor connector is subject, as there is almost no current through that. Remove the cap, rotor, and inspect. Inspect the inside of the distributor for rust, debri, strike damage, and shaft wobble. Get a brass feeler gauge, and set reluctor gap at .008".....inches not metric. O'Reallys has brass feelers

Hook your multimeter on low AC that's right, AC volts to the distributor connector. Crank the engine....the distributor should generate about 1V AC

Also, when testing a system that won't work, but which is getting 12V, you can ground one of the distributor connector terminals leading to the ECU. I don't remember which, try them both. Every time you ground it, one spark should be produced.

This is the diagram from the 72 shop manual, and may or may not be "physically correct" for 73

Wire no J3--14BR which goes from pin 22 of the bulkhead to the top left terminal of the ballast is the power for starting, IE the IGN2 or "bypass" circuit

The two connectors on the right side of the resistor are pooly drawn. These are jumpered together, and are connected to the IGN1 "run" circuit