1974 Dart 318 crank, but no start (Solved)

[jeff alder]

You guys helping with this wiring are the best! I did a 67 engine compartment when I was in high school and damn near pulled my hair out. Now I am almost completely Bald. I finally put a jumper across the ballast resistor and BINGO. Then I unbolted it and saw it was completely burnt open behind the ceramic. I wish I had you guys back then.

 

[Rhino_74Dart]

How am I being an asshole? I was just trying to help. I never purposely attacked you or said anything bad about you. So I'm sorry that you are a sensitive Karen and I hurt your feelings.

Telling me it's so bad I should rip it out and start over isn't saying anything bad to, or about me? Okay boomer. You didn't offer any help to my post, only bashed it. I'm sure all of your cars were show cars all the way thru the building phases, right?

 

[Rhino_74Dart]

So the wire from the wiper resistor to the coil is wrong.
That's probbaly a 5 or 8 ohm resistor. I didnt see the spec for the 2 speed wiper in a quick look at the FSM but its probaly in that range.

I have swapped out the resistor, got same results, and I have another on order, but it ran with the existing resistor in place, drove into the garage then tore it apart, and yes, it's a newer ECU, only has 4 pins in it

 

[Ant]

Telling me it's so bad I should rip it out and start over isn't saying anything bad to, or about me? Okay boomer. You didn't offer any help to my post, only bashed it. I'm sure all of your cars were show cars all the way thru the building phases, right?

Ok, I'll give you a wall of helpful text you.

Assuming you wired everything correctly.
And you have a 4 pin ECU/ICM.

Tools you need are:
A non LED test light
A multimeter

Key in run, you should have full-ish battery voltage at one end of the properly used ballast resistor and reduced voltage like 6 or so volts at the other end that has the wire that goes the coil. If no voltage at all, check your wiring or ignition switch circuit.

key in run, if you have full battery voltage at one end of the ballast resistor and no voltage at all at the other end, you need a new ballast resistor. If you put a jumper lead across both sides of the single ballast resistor or 12 volt power to the coil feed of the dual resistor, you should be able to now energize the coil.

Key in start, you should now have full battery voltage at the other end of the ballast resistor that has the lead that goes to the coil, because there is another lead that spliced in that supplies full battery voltage when cranking. If no voltage, check you wiring and ignition switch circuit. (I am aware that on certain vehicles it my get power from the starter relay)

Ok, let's say things look good at the ballast resistor so far. Let's move on to the ignition coil.
Key in run, you should have 6 or so volts at the positive end of of the coil. If not, check the wiring.
Key in start, you should have full battery voltage at the positive end of the coil. If not check the the circuit, maybe with a test light, I've encountered wires just good enough to show voltage, but fail under load.

All looks good so far? Moving on then.
Key in run, check the voltage on the negative side of the coil. If you get full battery voltage, suspect an open circuit in the wiring, a bad ECU or ECU ground.
Using a test light on the negative side of the coil, key in start with the engine cranking, the test light should flash. If it does flash and you still have no spark coming directly from the coil, you have a bad coil. If the test light does not flash, you may have an issue with the ECU, distributor pickup, or the circuit for the distributor pickup that goes the the ECU.

Now let's get into the distributor pickup.
As each tooth of the reluctor passes by the pickup a voltage signal is generated and picked up by the ICM/ECU which will break and complete the connection of the negative side of the ignition coil. You can use a scope to check the pickup, but most of us may not have a scope, so a normal multimeter will do fine. With the multimeter on the AC voltage setting and the two multimeter leads in the two connections from the pickup and the engine cranking you should a very low voltage reading, like around .2vac or close. If you see nothing, it's most likely nfg (of course you should also check the reluctor to pickup gap if you messed with that).

Other things to check:
Voltage to power the ECU/ICM is there at the connector.
Pickup signal at the ECU connector.
Wiggle check wires.
Coil to distributor and Spark plug wires.
Cap and rotor.

I hope that is helpful enough for you. I don't know the color of your wires, so that is for you to figure out.

Mic drop!

 

[George Jets]

Sounds like a No Spark to me. Run straight 12 volts to the coil for a test fire.

You know a "Hot Wire".

After it starts, then go back in and wire in the proper ballast inline resistor.

 

[Rhino_74Dart]

Ok, I'll give you a wall of helpful text you hotshot yuppie.

Assuming you wired everything correctly.
And you have a 4 pin ECU/ICM.

Tools you need are:
A non LED test light
A multimeter

Key in run, you should have full-ish battery voltage at one end of the properly used ballast resistor and reduced voltage like 6 or so volts at the other end that has the wire that goes the coil. If no voltage at all, check your wiring or ignition switch circuit.

key in run, if you have full battery voltage at one end of the ballast resistor and no voltage at all at the other end, you need a new ballast resistor. If you put a jumper lead across both sides of the single ballast resistor or 12 volt power to the coil feed of the dual resistor, you should be able to now energize the coil.

Key in start, you should now have full battery voltage at the other end of the ballast resistor that has the lead that goes to the coil, because there is another lead that spliced in that supplies full battery voltage when cranking. If no voltage, check you wiring and ignition switch circuit. (I am aware that on certain vehicles it my get power from the starter relay)

Ok, let's say things look good at the ballast resistor so far. Let's move on to the ignition coil.
Key in run, you should have 6 or so volts at the positive end of of the coil. If not, check the wiring.
Key in start, you should have full battery voltage at the positive end of the coil. If not check the the circuit, maybe with a test light, I've encountered wires just good enough to show voltage, but fail under load.

All looks good so far? Moving on then.
Key in run, check the voltage on the negative side of the coil. If you get full battery voltage, suspect an open circuit in the wiring, a bad ECU or ECU ground.
Using a test light on the negative side of the coil, key in start with the engine cranking, the test light should flash. If it does flash and you still have no spark coming directly from the coil, you have a bad coil. If the test light does not flash, you may have an issue with the ECU, distributor pickup, or the circuit for the distributor pickup that goes the the ECU.

Now let's get into the distributor pickup.
As each tooth of the reluctor passes by the pickup a voltage signal is generated and picked up by the ICM/ECU which will break and complete the connection of the negative side of the ignition coil. You can use a scope to check the pickup, but most of us may not have a scope, so a normal multimeter will do fine. With the multimeter on the AC voltage setting and the two multimeter leads in the two connections from the pickup and the engine cranking you should a very low voltage reading, like around .2vac or close. If you see nothing, it's most likely nfg (of course you should also check the reluctor to pickup gap if you messed with that).

Other things to check:
Voltage to power the ECU/ICM is there at the connector.
Pickup signal at the ECU connector.
Wiggle check wires.
Coil to distributor and Spark plug wires.
Cap and rotor.

I hope that is helpful enough for you. I don't know the color of your wires, so that is for you to figure out.

Mic drop!

Thank you, I have a new ECU, resistor, and dist. pickup coil on order, I will use your post to troubleshoot once they arrive. I am just trying to get this thing running to move onto next part. I was just asking for help, and your 1st comment rubbed me the wrong way. Do you have a Youtube video out on diagnosing Chrysler ignitions? Cause your profile pic looks a lot like the motor in the video, and if so, I've watched it a few times trying to figure out my issue, but there were some parts I didn't understand which is why I came to the forums. I can't wait for parts to arrive so hopefully I can get past this frustrating hurdle.

 

[Rhino_74Dart]

Sounds like a No Spark to me. Run straight 12 volts to the coil for a test fire.

You know a "Hot Wire".

After it starts, then go back in and wire in the proper ballast inline resistor.

I have full batt voltage on both sides of the coil in run and start positions, it's gotta either be the pickup coil died, or the ECU/ICM did

 

[George Jets]

I bought a points distributor for this very reason.

70.00 at rock auto new.

To get them running when all else fails. One wire.....

☆☆☆☆☆

 

[Mopar Tim]

I have full batt voltage on both sides of the coil in run and start positions, it's gotta either be the pickup coil died, or the ECU/ICM did

I do not think there should be full voltage on both points on coil. One side is for "ground" Not actually with electronic but same function. But I might be wrong. @Mattax will for sure know for sure!!!

 

[Ant]

Thank you, I have a new ECU, resistor, and dist. pickup coil on order, I will use your post to troubleshoot once they arrive. I am just trying to get this thing running to move onto next part. I was just asking for help, and your 1st comment rubbed me the wrong way. Do you have a Youtube video out on diagnosing Chrysler ignitions? Cause your profile pic looks a lot like the motor in the video, and if so, I've watched it a few times trying to figure out my issue, but there were some parts I didn't understand which is why I came to the forums. I can't wait for parts to arrive so hopefully I can get past this frustrating hurdle.

I don't have a video, but you can look up Scanner Danner, he pretty much covers the similar stuff in one of his videos on mopar ignition systems. I could make a video on reading diagrams and diagnosing the ignition system since I was an automotive mechanic a long time ago, but Scanner Danner does a much better job.

 

[Kendog 170]

@halifaxhops was selling some ignition manuals. OH, and glad you guys resolved the disagreement.

 

[Rhino_74Dart]

Ok, I'll give you a wall of helpful text you hotshot yuppie.

Assuming you wired everything correctly.
And you have a 4 pin ECU/ICM.

Tools you need are:
A non LED test light
A multimeter

Key in run, you should have full-ish battery voltage at one end of the properly used ballast resistor and reduced voltage like 6 or so volts at the other end that has the wire that goes the coil. If no voltage at all, check your wiring or ignition switch circuit.

key in run, if you have full battery voltage at one end of the ballast resistor and no voltage at all at the other end, you need a new ballast resistor. If you put a jumper lead across both sides of the single ballast resistor or 12 volt power to the coil feed of the dual resistor, you should be able to now energize the coil.

Key in start, you should now have full battery voltage at the other end of the ballast resistor that has the lead that goes to the coil, because there is another lead that spliced in that supplies full battery voltage when cranking. If no voltage, check you wiring and ignition switch circuit. (I am aware that on certain vehicles it my get power from the starter relay)

Ok, let's say things look good at the ballast resistor so far. Let's move on to the ignition coil.
Key in run, you should have 6 or so volts at the positive end of of the coil. If not, check the wiring.
Key in start, you should have full battery voltage at the positive end of the coil. If not check the the circuit, maybe with a test light, I've encountered wires just good enough to show voltage, but fail under load.

All looks good so far? Moving on then.
Key in run, check the voltage on the negative side of the coil. If you get full battery voltage, suspect an open circuit in the wiring, a bad ECU or ECU ground.
Using a test light on the negative side of the coil, key in start with the engine cranking, the test light should flash. If it does flash and you still have no spark coming directly from the coil, you have a bad coil. If the test light does not flash, you may have an issue with the ECU, distributor pickup, or the circuit for the distributor pickup that goes the the ECU.

Now let's get into the distributor pickup.
As each tooth of the reluctor passes by the pickup a voltage signal is generated and picked up by the ICM/ECU which will break and complete the connection of the negative side of the ignition coil. You can use a scope to check the pickup, but most of us may not have a scope, so a normal multimeter will do fine. With the multimeter on the AC voltage setting and the two multimeter leads in the two connections from the pickup and the engine cranking you should a very low voltage reading, like around .2vac or close. If you see nothing, it's most likely nfg (of course you should also check the reluctor to pickup gap if you messed with that).

Other things to check:
Voltage to power the ECU/ICM is there at the connector.
Pickup signal at the ECU connector.
Wiggle check wires.
Coil to distributor and Spark plug wires.
Cap and rotor.

I hope that is helpful enough for you. I don't know the color of your wires, so that is for you to figure out.

Mic drop!

Yea, I have no clue. New ECU, New pickup coil, coil swapped to known working coil, new ballast resistor. NOTHING CHANGED! Full batt volt. on both sides on coil,, test light dims but wont flash while cranking on - side of coil. Key in run, full batt volt everywhere, ballast resistor not dropping volts. Spark tester came in, no spark from coil. Something in the ignition isn't grounding I think, but don't know where. 2 ECUs, 2 pickup coils, 2 ballast resistors, 2 coils, and all do the same thing. This car is driving me nuts, it ran prior to wiring removal, now wont start with all new parts.

Full batt volt on both sides of coil, but if I hit the wire at ecu connecter that is connected to negative side of coil, it only registers like .56 volts, but coil side is over 12 volts.

And for what's its worth, I put new resistor on, tried, then new ecu, tried, then pickup coil, tried, then coil and tried. At no point did it ever do anything different. No spark.

 

[Bewy]

[1] Remove dist cap & crank engine to make sure rotor rotates. Check rotor for carbon tracking.
[2] Dist rotates. Remove dist, but first note position. Measure from vac adv nipple to f/wall or similar; note where rotor points. Connect DVM to dist p/up wires, select AC volts. Depending on how fast you spin the shaft, you should get from millivolts to a few volts if p/up is working. Wiggle wires while doing this to check for a broken wire.
[3] Say a prayer to Allah....

 

[Kendog 170]

Anyone have a definitive answer to post # 34?

 

[92b]

Full batt volt on both sides of coil, but if I hit the wire at ecu connecter that is connected to negative side of coil, it only registers like .56 volts, but coil side is over 12 volts.

I have a few of questions about this statement. You may have answered these already so bear with me.
What is the voltage at the battery (volt meter + to batt+ and volt meter - to battery -)?
With all the wires connected and the key in the run position . With the meter - connected to the battery - what is the voltage at the coil positive and coil negitive (there should only be one wire on the coil negitive)?
With the ignition module unplugged and the key in the run position. What is the voltage at the coil positive and the coil negitive?
With the key in the run position and the ignition module unplugged. By hand, trace the wire on the negitive side of the coil to the unplugged end of the ignition module plug (there should be no other wires connected to this wire). What is the voltage at the unplugged end of the ignition module plug?

 

[Ant]

Full batt volt. on both sides on coil,, test light dims but wont flash while cranking on - side of coil.

You have a problem with the circuit or you are not checking it right. Full battery voltage on the negative side means that there is an open circuit/ loss of connection from coil negative to the module and possibly ground.

Unplug the ICM connector and with the key in run check for voltage at the pin for the negative coil wire. You should have 12 volts there, because you just created an open circuit at the connector, but because it's giving full battery voltage, that means that there is no break in the wire from the coil to the ICM.

 

[Rhino_74Dart]

You have a problem with the circuit or you are not checking it right. Full battery voltage on the negative side means that there is an open circuit/ loss of connection from coil negative to the module and possibly ground.

Unplug the ICM connector and with the key in run check for voltage at the pin for the negative coil wire. You should have 12 volts there, because you just created an open circuit at the connector, but because it's giving full battery voltage, that means that there is no break in the wire from the coil to the ICM.

Yup, I knew it was gonna be something stupid, most likely my fault, and was correct. Got home from work, popped connector off, tested voltage, nadda at ICM side of wire from - side of coil. Thought maybe the new harness I bought was bad, but thought I better check my 1 connection on that wire, the eyelet....AAW kit came with black insulators to cover the crimp connections, as I slid it back, the wire fell out, leaving the eyelet and a few strands of wire connected to coil.....stripped wire, crimped on a new eyelet, bolted back on the coil, instantly got my reduced voltage thru ballast, and the damn car started! So now I have a bunch of backup ignition parts, lol. Thank you for your help, If you hadn't said to check the unplugged side of wiring, dunno how much longer this would have stumped me. Now that it runs, I can move forward, Thanks again all that chimed in.

 

[Ant]

Yup, I knew it was gonna be something stupid, most likely my fault, and was correct. Got home from work, popped connector off, tested voltage, nadda at ICM side of wire from - side of coil. Thought maybe the new harness I bought was bad, but thought I better check my 1 connection on that wire, the eyelet....AAW kit came with black insulators to cover the crimp connections, as I slid it back, the wire fell out, leaving the eyelet and a few strands of wire connected to coil.....stripped wire, crimped on a new eyelet, bolted back on the coil, instantly got my reduced voltage thru ballast, and the damn car started! So now I have a bunch of backup ignition parts, lol. Thank you for your help, If you hadn't said to check the unplugged side of wiring, dunno how much longer this would have stumped me. Now that it runs, I can move forward, Thanks again all that chimed in.

Good to hear.
You know what's funny though? If you did what I said to do in my first comment, you would have probably found the issue sooner. Hahahaha!

Anyway, lol, now you have a good amount of the info on how to check the primary side of your ignition system and figured it out the long, fun, but also correct way. Also, you probably learned more doing it this way, so that's another positive.

 

[92b]

Full batt volt on both sides of coil, but if I hit the wire at ecu connecter that is connected to negative side of coil, it only registers like .56 volts, but coil side is over 12 volts.

This bit of information here is what gave it away. Good for you to post all the information you had. Glad you have it running.