Ignition Issues - ‘74 Dart Sport

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SpriceyStuff

SpriceyStuff

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I’ve posted here before about this issue, but it seems that nothing has come of it. I’ve replaced the wiring harness and swapped engines and there is no change. I have no spark. I know my ignition switch is faulty, but I can’t get to it at the moment because I can’t get the retaining pin off the steering lock wheel. But that shouldn’t be the issue I’m having now… I have no voltage at the ballast resistor in the run position. When cranking, the voltage at the ballast goes up to 0.085v. Obviously this isn’t enough voltage to create spark, but I can’t figure out why it’s doing this. It’s a brand new ballast resistor, so it shouldn’t be out of spec. I’ve spent so many 12+ hour days working on what should be a simple issue but it’s clearly not as simple as one would think. Please. PLEASE help me. I’m about ready to give up on this car at this point.
 
I sent you a PM

The "path" for the ignition power IN THE "run" position of the key is Starter relay stud (battery)--through fuse link--through bulkhead connector (RED) through ammeter circuit, out ammeter (BLACK) to the WELDED SPLICE (up behind cluster taped up in harness)---branch off to key switch BATTERY terminal, through the switch connector, the switch, back out the switch connector on the "IGN1 run" wire--through the bulkhead connector and out into the engine bay. From there it branches off and supplies the underhood loads as equipped---VR IGN terminal, alternator field (blue) ignition system (ballast) electric choke if used, and "smog doo dads" on some models
 
Check power in the "run" position at the key switch, and follow that out through the bulkhead.....standby............

Also check "the stupid" connector. This is a white rectangular connector which separates the wiring right at the engine from the firewall harness. These are prone to failure. Bypass it if it is at all damaged

Also look on the driver side fender apron for a small box with a (used to be red) reset button. This is the seat belt interlock. Permanently splice the two yellowish wires together, which break the starter relay connection when it trips

bulkhead.jpg


dash.jpg


ignSwitch.jpg

Below the ignition switch is not quite drawn correct. The starter circuit is isolated, all by itself.

S2-12Y activates the start relay through the forementioned seat belt reset/ interlock
J3 -12BR is the ballast resistor bypass circuit and is also hot in start, feeds full power to the coil+ for a hot starting spark
J10-12R is battery power feeding switch, hot at all times
J2A 12DBL (Dark BLue is the IGN1 "run" wire
Q2- 12BK (BlacK) is accessory
igndiag.jpg
 
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74 and newer harnesses suck. I fixed this 74 dart picture below to get the Barracuda. Same issue and several wanna be engineers couldn't fix it . It had me stumped for a little while, The bulkhead connectors were corroded where the wires go into the spades.. You had to pull them out of the white plastic one by one to see it.

106_0290.JPG


106_0291.JPG
 
Oldmanmopar said:
74 and newer harnesses suck. I fixed this 74 dart picture below to get the Barracuda. Same issue and several wanna be engineers couldn't fix it . It had me stumped for a little while, The bulkhead connectors were corroded where the wires go into the spades.. You had to pull them out of the white plastic one by one to see it.

View attachment 1715936719

View attachment 1715936720
Click to expand...

alright I’ll give er a shot this weekend
 
Well boys, I couldn’t do it today. I went over there with a positive attitude but I didn’t even get to break out the multimeter and find out where I was losing voltage because the moment I hooked up the battery cables the Hotwire started smoking and the fusible link burned out.
 
Oh MAN!!!. I've posted this before---and of course you may not know you HAD a short, but when you suspect a short or know you do, put a big wattage 12V lamp like backup, turn lamp in series with the battery

First thing "I'd check" is the alternator output stud connection. Is the wire shorted, is the alternator shorted, etc?
 
67Dart273 said:
Oh MAN!!!. I've posted this before---and of course you may not know you HAD a short, but when you suspect a short or know you do, put a big wattage 12V lamp like backup, turn lamp in series with the battery

First thing "I'd check" is the alternator output stud connection. Is the wire shorted, is the alternator shorted, etc?
Click to expand...
No I just wired those up not long ago they’re good. I know there’s some janky wiring under the dash tho…
 
SpriceyStuff said:
No I just wired those up not long ago they’re good.
Click to expand...
It's best not to assume anything. The fact that you just changed a wire doesn't guarentee the alternator didn't short internally or that the wire didn't get pinched or grounded.

If there is nothing supoer obvious visually, use the ohmeter to find the location.
First very verify the short shows up by connecting one lead to the circuit and the other to ground.
Then disconnect the alt output wire (Batt terminal) and see if that solves it. If not, keep going. Disconnect each wire connecting back to the battery wire until you find the short.

Just look at the unfused wires that are normally always connected to the battery. In other words, always hot.
upload_2022-6-5_9-33-6.png


We know the short occured with nothing turned on, and on the other side of the fusible link.
So one of these made a good connection to ground - good enough the fusible link went poof real fast.
upload_2022-6-5_9-40-24.png
 
Mattax said:
It's best not to assume anything. The fact that you just changed a wire doesn't guarentee the alternator didn't short internally or that the wire didn't get pinched or grounded.

If there is nothing supoer obvious visually, use the ohmeter to find the location.
First very verify the short shows up by connecting one lead to the circuit and the other to ground.
Then disconnect the alt output wire (Batt terminal) and see if that solves it. If not, keep going. Disconnect each wire connecting back to the battery wire until you find the short.

Just look at the unfused wires that are normally always connected to the battery. In other words, always hot.
View attachment 1715937540

We know the short occured with nothing turned on, and on the other side of the fusible link.
So one of these made a good connection to ground - good enough the fusible link went poof real fast.
View attachment 1715937542
Click to expand...

alroght I’ll check it out tomorrow when I get some time off work. Thank you
 
If you don't already have a FSM, go to Mymopar & print one out. It will save you time, trouble & headaches in the long run.
 
So I’ve finally gotten some time to work on the car again. Now that I’ve finally gotten over the hurdle of putting the new ignition switch in, some problems have been solved, but others remain. I checked voltage in a few different places. From the starter relay all the way to the Hotwire going into the ignition switch, I had about 12.14 volts. With the key in the run position, I began checking the run wire. At the plug, 11.75v. At the bulkhead, 11.75v. At the ballast resistor, 11.75v (both sides). The wire then goes to the ignition control module. I still have no spark, but I will have to get new mounting screws for the ICM so that it can be firmly mounted and properly grounded to see if that is the cause. If not, I will move on. Although I’m not sure what else to check after that, as I’ve already traced those wires to their proper places.
 
OK back to basics. That voltage is low, but "workable" for now. You need to find out if you have voltage to the ignition when cranking. The circuit for cranking power is different than "run." So hook your meter to the coil + and turn the key to run. You should see maybe 6--10 volts, not any higher and not much if any lower.

Now crank the engine, using the key, and see what you have. You should have "same as battery" that is whatever the battery itself reads WHEN CRANKING you should have close to that at the coil+
 
The Ignition module (ECM) has to see the Battery negative, from case to apron to battery.
Every good-working module that I have ever tested, will give a spark out the coil-wire, when the ignition switch is turned from run to off. I call this the one spark test. If yours does this, then this leaves only a few potential candidates for a no spark while cranking situation. They are:
the Magnetic pick-up has failed
the distributor mainshaft is Not spinning
the reluctor gap is too large,
the reluctor has become magnetized
 
AJ/FormS said:
The Ignition module (ECM) has to see the Battery negative, from case to apron to battery.
Every good-working module that I have ever tested, will give a spark out the coil-wire, when the ignition switch is turned from run to off. I call this the one spark test. If yours does this, then this leaves only a few potential candidates for a no spark while cranking situation. They are:
the Magnetic pick-up has failed
the distributor mainshaft is Not spinning
the reluctor gap is too large,
the reluctor has become magnetized
Click to expand...

You can also, with the key in "run" take the engine bay end of the distributor connector, and tap the bare terminal against ground and create a single "snap" spark each time
 
Alright guys thanks to all of you and some others, this car now starts and runs! We got it to start sparking, but the distributor was WAYYYY off time so I spent over an hour adjusting that, mostly it was sparking late and shooting giant flames out the exhaust. Now it runs like a top! Only trouble is, it starts up and tries to drive away so tomorrow my brother and I will try and tackle the shift linkage not being adjusted properly.
 
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