Please help!! 1971 340 duster having major ignition wiring headaches.

[sassygrnduster]

Hi all, I need some serious wiring help for my ignition setup. I’m not electrical savvy but have read about 20 post and tried others suggestions that they commented before making my own post but nothing seems to work. The one good thing is I am learning a lot about the electrical the hard way lol I’ve been restoring this car since I was 16 and I’m almost ready to drive but this wiring has held me up for over 2 weeks.
2 weeks ago I finished hooking up all the electrical, got in the car and she cranked instantly and idled great. I did this about 10 times over 2 days (very proud of getting it finally cranked for the first time) Then I go to work come back to show my son how it sounds and it struggles for the first time and won’t crank (does turn over) I tried 2 more times and then boom a big back fire out the exhaust a 2 second idle and then died. (Also saw a little fuel spray out the top of the carb) I figured it was flooded waited until morning to try again and ever since it will turn like it wants to start but never starts and has backfired a couple more times. After reading all the post I changed the single ballast, ICM, and ignition coil, just to see if it was one of those. Then I tried measuring test with my multimeter and wasent showing what other people said it should be. So now I checked all wires for damage or grounding out, pulled the center bulk head disconnect and double checked my wiring and can’t find anything causing the bad reads.

So this is what I got
Single ballast, ignition coil and ICM
I am getting 12v read at battery
I am getting 9.8v read on hot side of ballast
I am getting 9.6V on right side of ballast
I am getting 9.8V on +side of coil with key in on position
I am getting 1V on -side of coil with key in on position
I am getting 11.2V when reading #1 socket hole on ICM wiring plug
*** When cranking the coil +side drops from 9.6V to 4.2 Volts*****

I have a wire going from the +side of the coil, spliced into my dark blue ign 1 wire (actually two blue wires that were connected to the same plug) plugged into left side of ballast.

Then I have my black and yellow wire from my ICM plug to my coil -side

Also I have my blue and yellow wire from my ICM spliced into my brown Ign 2 wire (actually 2 brown wires, they were already connected to the plug from original harness) plugged into the right side of my ballast.

Please help, any and all suggestions welcome.

 

[69FBCuda]

Hi all, I need some serious wiring help for my ignition setup. I’m not electrical savvy but have read about 20 post and tried others suggestions that they commented before making my own post but nothing seems to work. The one good thing is I am learning a lot about the electrical the hard way lol I’ve been restoring this car since I was 16 and I’m almost ready to drive but this wiring has held me up for over 2 weeks.
2 weeks ago I finished hooking up all the electrical, got in the car and she cranked instantly and idled great. I did this about 10 times over 2 days (very proud of getting it finally cranked for the first time) Then I go to work come back to show my son how it sounds and it struggles for the first time and won’t crank (does turn over) I tried 2 more times and then boom a big back fire out the exhaust a 2 second idle and then died. (Also saw a little fuel spray out the top of the carb) I figured it was flooded waited until morning to try again and ever since it will turn like it wants to start but never starts and has backfired a couple more times. After reading all the post I changed the single ballast, ICM, and ignition coil, just to see if it was one of those. Then I tried measuring test with my multimeter and wasent showing what other people said it should be. So now I checked all wires for damage or grounding out, pulled the center bulk head disconnect and double checked my wiring and can’t find anything causing the bad reads.

So this is what I got
Single ballast, ignition coil and ICM
I am getting 12v read at battery
I am getting 9.8v read on hot side of ballast
I am getting 9.6V on right side of ballast
I am getting 9.8V on +side of coil with key in on position
I am getting 1V on -side of coil with key in on position
I am getting 11.2V when reading #1 socket hole on ICM wiring plug
*** When cranking the coil +side drops from 9.6V to 4.2 Volts*****

I have a wire going from the +side of the coil, spliced into my dark blue ign 1 wire (actually two blue wires that were connected to the same plug) plugged into left side of ballast.

Then I have my black and yellow wire from my ICM plug to my coil -side

Also I have my blue and yellow wire from my ICM spliced into my brown Ign 2 wire (actually 2 brown wires, they were already connected to the plug from original harness) plugged into the right side of my ballast.

Please help, any and all suggestions welcome.

Did this configuration run before?
Did you pull the distributer prior to the not starting?

 

[moparlvr166]

Question: after it started and ran did you set the timing and tightened the distributor down, so it won't move?

 

[sassygrnduster]

Did this configuration run before?
Did you pull the distributer prior to the not starting?

Yes the configuration I listed was how it was when it ran before the issue

 

[sassygrnduster]

Question: after it started and ran did you set the timing and tightened the distributor down, so it won't move?

The distributed was tightened down before starting and is still tight and don’t move. Also it ran and idled very well so it seemed the timing was spot on. Would any of that cause the readings to be off and the Volts on the +side of the coil to be reducing to 4V when trying to crank instead of reading the 12V I believe it’s supposed to be showing when turning the key to crank?

 

[Mike69cuda]

What kind of ignition system does it have? Points? Chrysler electronic ignition? Some thing else?

 

[tonysrt]

Does the engine crank over fairly good? Battery voltage at 12 volts may seem a little low. If you have a charger put it on for a few hours and try it then. If it runs make sure charging volts is about 13.6volts or that ammeter shows it is charging. I had a 12 volt battery that would drop to 9.5 volts when cranking, bought a new battery and solved my problem. I keep a trickle charger on, because only run the car once a week or sometimes once a month depending on the weather..

 

[Kendog 170]

How old is the Battery? Definitely give it a charge. You could have a couple of bad cells that die out when cranking.
And as said what Ignition are you running?

 

[halifaxhops]

This will walk you right through the mopar electronic ign. If you are using a "new" orange box they are really iffy now also

[SOLD] - Electronic ignition trouble shooting guide.

I have some copies of a great book for trouble shooting Mopar electronic ignition with a ohm meter. Askin $21 shipped lower 48

www.forabodiesonly.com

 

[67Dart273]

So this is what I got
Single ballast, ignition coil and ICM
I am getting 12v read at battery
I am getting 9.8v read on hot side of ballast
I am getting 9.6V on right side of ballast
I am getting 9.8V on +side of coil with key in on position
I am getting 1V on -side of coil with key in on position
I am getting 11.2V when reading #1 socket hole on ICM wiring plug
*** When cranking the coil +side drops from 9.6V to 4.2 Volts*****

I have a wire going from the +side of the coil, spliced into my dark blue ign 1 wire (actually two blue wires that were connected to the same plug) plugged into left side of ballast.

Then I have my black and yellow wire from my ICM plug to my coil -side

Also I have my blue and yellow wire from my ICM spliced into my brown Ign 2 wire (actually 2 brown wires, they were already connected to the plug from original harness) plugged into the right side of my ballast.

Please help, any and all suggestions welcome.

The 4.2 when cranking means the starting/ ballast bypass IGN2 circuit is not working or wired wrong

"

I have a wire going from the +side of the coil, spliced into my dark blue ign 1 wire"

This sounds wrong. The blue is normally the IGN1 "run" coming from the key into the engine bay. That (if the one) feeds VR IGN terminal, alternator field, the key side of the ballast (not the coil directly)

Somehow I missed: What is the reason for this rewiring? Did the car have another system and you added this? Or is this some trial and error to get it working, or what?

 

[67Dart273]

DIAGRAMS BE CAREFUL

Aftermarket, simplified wiring diagrams can lead you astray, there are two general problems

1: Some diagrams show the box connector looking INTO the FRONT of the WIRE end harness connector. Some diagrams are drawn as looking at the FRONT of the box itself This produces a MIRROR image. This diagram is looking down at the front of the BOX

2...Second and this is a MISTAKE is some label the BYPASS circuit as if it goes to "START." THIS IS NOT CORRECT.

In the diagram below, the "S" START wire at top right DOES NOT come from the (normally) yellow "start" wire from the key, and which fires the "start" relay. This instead comes from IGN2 on the key which is a SEPARATE contact to prevent backfeed

HOW THIS works. With the key in run AND ONLY IN RUN and in NO other position, the blue "run" wire feeds power into the engine bay. This goes through the ballast to the coil, and branches off to the ECU box

Most any box you will find nowadays is a FOUR wire box, and if plugged into EITHER a factory 2 terminal ballast harness, or a 4 terminal ballast harness, WILL work. A true 5 pin box will NOT work with a 2 pin ballast. YOU CAN NOT identify a 4 pin box by looking, as some have 5 physical pins

WHEN STARTING, and the key is held to "start", the IGN2 terminal of the key becomes live and sends power to the wire labled START. The RUN IGN1 line (bottom right) GOES DEAD at the key. The BYPASS/ IGN2 circuit (labled start) IS THE ONLY power during cranking.

This power feeds through the terminal on the ballast, direct to the coil, and SHOULD provide near full battery voltage to the coil for start. The NEG side of the coil goes to the box and to ground---THE BOX MUST be grounded.

HOW DOES the box get power for starting. Power at the top terminal of the ballast flows through the ballast and over to the box, so the box actually receives REDUCED voltage during cranking. (Why this was done the way is beyond me)

 

[George Jets]

Poping back through the carb, good chance the loose timing chain jumped a tooth or 2.

Easy test, set the distributor cap off to the side so you can see the distributor rotor.

Then get a socket on the front crank pulley bolt head with a breaker bar and rock it back and forth to see if there is excessive delay before the distributor rotor moves.

A little delay is OK, a lot of delay is not.

☆☆☆☆☆

 

[67Dart273]

Your voltage readings sound ?? partly because I don't know what right side and left side means. One side of the ballast is power from the ignition switch, the other side goes to the coil

WITH KEY IN RUN the switch side should be nearly same as battery. It rarely is, because the harness often has voltage drop.

The coil side of the ballast should show maybe 6-10V +/-. If it shows full battery, it means the coil is not drawing current, is open, or not getting ground through the box, or the box is not powered or defective

With the key in "start" and cranking, the coil + should be near full battery and in no case below 10V

HAVE YOU checked for spark and spark quality? "Rig" a solid core wire (can be low voltage wire if propped away from metal) from the coil tower to a spark gap tester, or a good plug gapped wide. Crank engine USING THE KEY. You should get snappy hot blue sparks at least 3/8 and typically 1/2" long

 

[sassygrnduster]

What kind of ignition system does it have? Points? Chrysler electronic ignition? Some thing else?

I just have the stock wiring, a ICM from Oriellys that pulled up for my 340 duster, the ballast and coil also from Oriellys that pulled up under and my distributor was put on by the guy who rebuilt my 340

 

[sassygrnduster]

Does the engine crank over fairly good? Battery voltage at 12 volts may seem a little low. If you have a charger put it on for a few hours and try it then. If it runs make sure charging volts is about 13.6volts or that ammeter shows it is charging. I had a 12 volt battery that would drop to 9.5 volts when cranking, bought a new battery and solved my problem. I keep a trickle charger on, because only run the car once a week or sometimes once a month depending on the weather..

Engine cranks really well it’s the battery

 

[sassygrnduster]

The 4.2 when cranking means the starting/ ballast bypass IGN2 circuit is not working or wired wrong

"

This sounds wrong. The blue is normally the IGN1 "run" coming from the key into the engine bay. That (if the one) feeds VR IGN terminal, alternator field, the key side of the ballast (not the coil directly)

Somehow I missed: What is the reason for this rewiring? Did the car have another system and you added this? Or is this some trial and error to get it working, or what?

So are you saying that my wire from the +coil side should be spliced into my brown wire which is on the opposite side of my ballast? To be clear I ran (spliced in) a single wire from my +coil side to the blue wire that runs from the (N) plug of the bulkhead disconnect( labeled ignition 1 in my wiring diagram)it plugs into the ballast and was there already with the stock wiring. If I’m not supposed to splice it in with that wire and just run it to the ballast directly and leave off the blue ignition 1 wire, where would that plug in then?

Also I got this car with a slant six, so we pulled the engine and tranny(plus everything else ) except the original wiring. It had no ballast, coil or ICM when I got it. Just engine, tranny and loose wires.
I really appreciate the help guys, thanks

 

[sassygrnduster]

Your voltage readings sound ?? partly because I don't know what right side and left side means. One side of the ballast is power from the ignition switch, the other side goes to the coil

WITH KEY IN RUN the switch side should be nearly same as battery. It rarely is, because the harness often has voltage drop.

The coil side of the ballast should show maybe 6-10V +/-. If it shows full battery, it means the coil is not drawing current, is open, or not getting ground through the box, or the box is not powered or defective

With the key in "start" and cranking, the coil + should be near full battery and in no case below 10V

HAVE YOU checked for spark and spark quality? "Rig" a solid core wire (can be low voltage wire if propped away from metal) from the coil tower to a spark gap tester, or a good plug gapped wide. Crank engine USING THE KEY. You should get snappy hot blue sparks at least 3/8 and typically 1/2" long

When I say left and right of ballast, I’m just saying which side looking at it directly from the grill of the car.

With the key in run position
One side of the ballast reads 9.8V
The other side reads 9.5V
The +coil shows 9.8
When I turn to crank it hoes down to 4.7V not up to 12V

Ran a jump wire from battery to plus coil and she fires right up and idles well.
Just can’t figure out why I can’t get 12V to the coil or why the ballast is showing the voltage it is

 

[moparlvr166]

It sounds like with the jumper wire it works.
Do you have a wire diagram to follow.
Do you have a good ground from engine to firewall, engine to battery, ICM to body?

 

[67Dart273]

So are you saying that my wire from the +coil side should be spliced into my brown wire which is on the opposite side of my ballast? To be clear I ran (spliced in) a single wire from my +coil side to the blue wire that runs from the (N) plug of the bulkhead disconnect( labeled ignition 1 in my wiring diagram)it plugs into the ballast and was there already with the stock wiring. If I’m not supposed to splice it in with that wire and just run it to the ballast directly and leave off the blue ignition 1 wire, where would that plug in then?

Also I got this car with a slant six, so we pulled the engine and tranny(plus everything else ) except the original wiring. It had no ballast, coil or ICM when I got it. Just engine, tranny and loose wires.
I really appreciate the help guys, thanks

I cannot see what you have so difficult to answer. But I DID say earlier that the coil/ ballast wiring is THE SAME for either points or a 4 pin ECU box. You should not have had to change ANYTHING on the factory wiring to the ballast, from the old points system

The run wire should already have been wired to the ballast.
The coil side of the ballast should already have the brown bypass/ IGN2 wired in.

If you connect the original coil + wire to the coil +, and run a new wire over to to the ECU from the coil NEG, ground the box, connect the two wire distributor connector, and then run the box power wire and splice that into the key side of the ballast (see the diagram I posted) that is all you need. To determine for sure which is key side of ballast and which is the coil side, simply unplug either connector at the ballast, turn the key to run, and then probe the two wires and see which one is "hot." That one is the feed from the key

In the diagram I posted, the (incorrectly) labled start wire and the "Run" wire should already be in place, if no one has chopped things up Again, all you need to add to that diagram is the power wire to the box, from the "RUN" connection at the bottom of the ballast

 

[harrisonm]

@sassygrnduster, listen carefully to what @67Dart273 says. I am pretty good with automobile electrics, and he has forgotten more than I'll ever know.

 

[Mattax]

Just can’t figure out why I can’t get 12V to the coil or why the ballast is showing the voltage it is

There will never be 12 Volts at the coil if everything is working correctly.
While the starter motor is running battery voltage gets pulled down. With a strong battery it will be around 11 Volts, and with high load or a weaker or old battery it may be 9.5 Volts but still start. Under 9 volts it probably won't start even with points ignition. Measuring the voltage at the battery with the starter motor turning is a way to test battery condition.

When I say left and right of ballast, I’m just saying which side looking at it directly from the grill of the car.

Means nothing. There's no way for any of us to know which side you plugged the wires into.
What is needed and useful is to know is which wire or circuit is being measured.
Choices are:
Run Circuit (labled on the diagrams as Ignition J2 and usually a blue wire) This supplies system power from the key switch when the key is in run.
Ignition Start (labled as Ignition J3 and is usually a brown wire). This supplies power from the key switch when the key is in start.
The ignition start is crimped to the wire going to the coil.

One side of the ballast reads 9.8V
The other side reads 9.5V
The +coil shows 9.8

This suggests very little current is flowing through the ballast resistor.
When the engine is running. Power is supplied from the run circuit. When the ECU closes the connection, power flows through the ballast resistor and coil. The resistor reduces the current flow and a voltage drop across the resistor can be measured. No current flowing, no reduction of voltage.

With a 4 pin ECU, a single 0.5 ohm ballast resistor will work like this.

 

[Mattax]

When the engine is running. Power is supplied from the run circuit.

Electric current is like water flowing though a pipe.
It flows from the alternator or battery to junctions where it branches off to circuits that need it.

Engine running, current flow looks like this.

When the ECU closes the connection, power flows through the ballast resistor and coil. The resistor reduces the current flow and a voltage drop across the resistor can be measured.

The coil negative wire is connected to ground every time the magnetic pickup signals the rotor has moved to the next spark plug.
The Chrysler 4 pin ECU is powered through the light blue wire. It draws power whenever the key is in Run (or start).

So the resistor drops the voltage in proportion to current flow.

Resistance varies with temperature, current flow varies with coil and rpm so I can't give you an exact number. An osciliscope is more useful than a meter for checking coil primary voltage.

 

[Mattax]

An osciliscope is more useful than a meter for checking coil primary voltage.

Live Coil Voltage Levels: Pix

FWIW.... if you ever wondered what the voltages at the + and - of a typical ignition coil really look like when running, and why you get those odd 6 to 10v readings on your voltmeter at coil + for example, here are some oscilloscope pix from a running ignition system. An oscilloscope presents...

www.forabodiesonly.com

 

[67Dart273]

Oh come on. Nobody needs to break out the scope to troubleshoot a wiring/ no spark problem.

 

[Mattax]

Oh come on. Nobody needs to break out the scope to troubleshoot a wiring/ no spark problem.

I agree. My point was to show why spending time measuring voltage at the coil positive or negative is not that helpful for solving wiring problems. Sassygrnduster is hardly unique in doing this and then wondering why we can't provide an answer.