Coil Negative getting power and not starting - Slant six

[Mopar King]

Hi everyone, I am having a few small electrical issues with dodge. The car was a big project but now it is almost done and I wanted to test out the engine by starting it and letting everything get warmed to see if it has any leaks or problems.


with that said, I did tried to start the car but didn't fired up. I started to check with a test light to see if it has power at all the right places which it did. I also discover that when the key is in the "ON" position (engine off) and with the test light on the negative side of the coil terminal it has power! I was wonder what would cause the coil negative to have power? i tight checking on-line but the key-search turned up nothing.

also both side of the ballast have full power when the key is at the ON position (engine off).


Details are as followed below

• 1972 Dodge Dart
• Slant six
• converted to the Mopar electronic system
• New reman. distributor, new cap, new rotor, new coil, new 1973 sqaureback alternator, new '73 Mopar Brand voltage regulator, new mopar brand orange box, new V.R. wiring harness, new spark plugs, new ballast resistor 2 pongs with metal hanger, new mini starter, old starter relay which i found laying around

 

[67Dart273]

It is normal to show "a little" power at the coil neg, did you measure voltage, or just put "a light" on it? Light is dim? normal

Is the ECU grounded FOR CERTAIN?

Full battery voltage on both sides of the ballast either indicates no current through the coil or a wiring problem in the ECU harness

Trace the neg. coil wire back to the ECU and make sure it's continuous

Make sure the ECU is grounded.

I assume? later model ECU with 2 pin resistor? Is it possible you have an older 5 pin box? You cannot tell "by looking," some replacement 4 pin boxes have 5 pins. You must check continuity from the "5th pin" to the other pins to see if there is any connection

Simplified "4 pin" ECU wiring:

 

[TrailBeast]

Power will flow all the way through the coil, as it is just a big roll of wire inside so power ar the neg terminal is normal. (Same with the ballast)
However, something is not telling the coil to fire by grounding and ungrounding it.
Is the distributor pigtail plugged in to your harness from the ignition module?
Is the ignition module harness plugged in.

Beat me to it Del (again)

"Full battery voltage on both sides of the ballast either indicates no current through the coil or a wiring problem in the ECU harness"

If the coil has no ground it could look like full voltage at both sides of the ballast.
Especially with a test light.

 

[Mopar King]

forgot to add : I also don't have any spark but I think it could be a few things

1. maybe I need to gap the reluctor inside the distributor since I just installed the distributor and left?
2. maybe i need the condenser?
3. maybe I need a ground strap from the engine block to frame/chassis
4. maybe spark plug wiring is incorrect
5. maybe timing is off again
6. maybe starter relay box is incorrect

Im just thinking, I'll check these tomorrow when i have time.


Im still worry and puzzled on why the coil is getting power to negative, my dad and me are still thinking it has to be a wrong wire misplaced somewhere or a defected coil - which is a duralast Gold coil part #C819G





forgot to add on the list of new items that i added.

• New summit racing blue spark plug wires - cut and shorted them to fit

here is a picture of the ballast resistor


sorry for all the details

 

[67Dart273]

Or to 'xplain a little more, if the test lamp on the coil neg is bright, we have a wiring or ECU problem,

If the test light is dim, "pretty dim," might be "normal."

forgot to add : I also don't have any spark but I think it could be a few things

1. maybe I need to gap the reluctor inside the distributor since I just installed the distributor and left?
2. maybe i need the condenser?
3. maybe I need a ground strap from the engine block to frame/chassis
4. maybe spark plug wiring is incorrect
5. maybe timing is off again
6. maybe starter relay box is incorrect

Make sure you have power to the coil when cranking. Try adding a clip lead from a battery source to coil+ during testing.

2--Condenser on coil+ only is for radio noise supression, not needed

3-Ground strap probably not the cause of this, but you DO need battery grounded to block and body

4--With no spark, plug wiring is irrelevant for now

5--Irrelevant for now

6--If engine cranks not a problem, and certainly not the cause of "no spark"

 

[Mopar King]

I have the mopar 4 pin ECU

- which the green cable is not used,
- black cable goes straight to negative side of coil,
- distributor cables goes to Distributor,
- coil positive has the brown cable going to ballast and going to Ignition 2 which is also brown
- blue cable goes in between the V.R, ballast and blue ignition 1 cable .

Im going to have to get another multimeter because the one i have doesn't work. I was just using the test light just to indicate if i have electricity going through certain areas.

as i said both the positive and the negative sides of the coil have power that the test light is bright on either side - same with the ballast

-Distributor pigtails are plugged in the dist. and the ECU but I make sure again just in case

I did tested out another car (1974 Plymouth scamp) just to see if it was doing the same thing. coils negative is off when key is in ON position (engine off) and the brown wire on the ballast is lightly dimmed while the blue wire is bright.


I going to have to do that tomorrow and see if that helps - taking some of the paint off the V.R. and the ECU

 

[Mopar King]

Or to 'xplain a little more, if the test lamp on the coil neg is bright, we have a wiring or ECU problem,

If the test light is dim, "pretty dim," might be "normal."




Make sure you have power to the coil when cranking. Try adding a clip lead from a battery source to coil+ during testing.

2--Condenser on coil+ only is for radio noise supression, not needed

3-Ground strap probably not the cause of this, but you DO need battery grounded to block and body

4--With no spark, plug wiring is irrelevant for now

5--Irrelevant for now

6--If engine cranks not a problem, and certainly not the cause of "no spark"

OK at least you knock them off my mind and list:thumblef:

 

[Mopar King]

I tried looking at everything again just to make sure i didn't make a mistake. Everything checks out except one thing ... The ECU orange box's wire harness wasn't fully plugged in. I also removed both the V.R. and the ECU and sanded the back to make better ground.


After that I tested the coil and now negative has no power, brown wire is lightly dimmed when key is in the ON position (engine off) and Blue wire is bright. car starts now and everything is warming up nicely. now I need to test the voltage levels and plug my voltage gauge to see if everything is truly alright. waiting for my new multimeter to get here.


simple mistake on my part, Thanks both you guys



The only problem i have is the oil gauge level being low but thats a different subject