Overcharging Issue & Car Start Issue

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fluctuating from 13-15.5 is not good. at idle i have 12.5 or so and cruising i have a solid 13.9-14. i think you have a loose/dirty connection somewhere or a bad ground. you need to work out the starting issue. first , i would make damn sure your ecu box is grounded, i just had the same problem where it wouldnt start until the key was on its way back to the start postion . it turned out be a bad ECU box . new box, fresh ground, been working ever since.
 
What actually do you check for in these pins? Do you spread the pins to make better contact? Do you ohm them while you wiggle them? Do a lot of people have these problems after replacing harnesses ? This is so frustrating doing this. I hate intermittent failures.
 
are you talking about the column harness ? some pics and a complete description of what you have going on would help
 
bvfs12 said:
Explain to me what the ECU box is. ECU is short for what?
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ECU is your Mopar Electronic Control Unit, the "ignition box." Yes, please go through the thread very carefully, and read that MAD article I posted the link to, earlier. It details what types of problems go wrong in the bulkhead connector

I also detailed the circuit path IE "what all" the power goes through on the way from the battery to the ignition, etc, earlier. There are several things of concern in that circuit.
 
I guess I'm a little confused. I've never heard of an ECU on my car. Now I might be all green here and never knew it on my car by that name but never heard it termed Electronic Control Unit. I have a 1970 Duster 340. What am I missing here. Please, educate me here.
 
bvfs12 said:
I guess I'm a little confused. I've never heard of an ECU on my car. Now I might be all green here and never knew it on my car by that name but never heard it termed Electronic Control Unit. I have a 1970 Duster 340. What am I missing here. Please, educate me here.
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Maybe we are missing something. Just what are you running for an ignition system?

Mopar ECU:

It can be black, chrome, orange, or blue.

ecu.jpg


Older boxes use a 4 pin ballast, newer ones use a 2 pin ballast

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ballast-resistor-5206436.jpg
 
Some ECU’s are orange as well.

But, you may not have on in your 1970 car, as it came from the factory with points. Unless your car has been upgraded with electronic ignition, you won’t find an ECU under the hood.
 
My car has an MSD electronic ignition along with a MSD ballast resistor.
 

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What model is the MSD?

It's very possible the MSD is causing electrical interferance in the rest of the system, and may be related to your overcharge condition.
 
wish we would have known this earlier, anything else i have to say would be pure speculation.....
 
The model of this MSD on this car is Pro-Billet Ready-to-Run Distributor P/N 8388. Coil is the Blaster II P/N 8202.

Funny thing is that I've been running with this coil and distributor for 5 years and never had a problem like this. I've seen these coils and distributors on other cars and they seem not to have a problem ..that I know of.
 
I have a question about one of the steps you mentioned in checking the voltage drop in the wiring harness.

You stated "Turn the key to "run" but with engine off. Select "low DC volts" range on the meter, put one probe on the battery positive post, the other on the blue field wire, and or, the IGN feed to the ballast and regulator IGN terminal"

When you put the probe on the blue field wire are you disconnecting any of the wires when your making these checks?

Another question I have is what is IGN1 used for ? Is it the line that is used when your key is turned backwards ? The reason I ask is when I do continuity checks on my ignition switch from Battery to IGN1 I have no continuity when the key is placed in run and start. These measurements were made at the connector end of the steering harness.
 
No when making the test, everything should be hooked up

The MSD ready to run is probably not going to cause the problem I mentioned


IGN1 is the ignition run (dark blue), and is hot only in "run" no other key position. I'm wondering if you made a mistake.

Since you are having problems, and have converted the ignition, I'm wondering if the brown bypass circuit came unhooked somehow.

I looked at the destructions for your ignition, and it appears to me that you should have bypassed the ballast resistor. Nevertheless, the brown bypass circuit should STILL supply 12V to the coil+ in start. This is the one referred to as IGN2 (brown, or bypass circuit)
 
I did some troubleshooting today and this is what I found.

I called the individuals who rebuilt my steering column. I asked the if they could make some continuity measurements on the ignition switch wiring harness for the 1970 Duster. They said that they had new one and they would be glad to accommodate me.

This was my findings:

I disconnected my ignition connector on the steering column from the main wiring harness. I place the ignition switch to the 2nd click (Run position)

Taking a volt ohm meter to make make some continuity checks I made measurement from the Red wire to the IGN1 (Blue) and had no continuity. The new cable showed continuity.

Taking a volt ohm meter to make make some continuity checks I made measurement from the Red wire to the IGN2 (Brown) and had continuity. The new cable showed no continuity.

I think that this is the reason that the car will not start when the key position is placed to start but will start when the key position comes back to run (IGN1)

I'll be receiving a new harness in a few days in the mail to confirm this. We're almost 100% sure that this is the problem and a new ignition switch is the fix.
 
You may be on the right track, but what you say makes no sense. The dark blue is live "in run" so if it's not working, how could the car run?

The brown is live in start, so why won't the car fire in "start?"
 
+1 on bad connection(s). The voltage regulator senses the 12V at the switched ignition supply. If the voltage dips, the regulator boosts the field so the alternator voltage increases. So if the ignition circuit is a volt low, the battery voltage is a volt high.

Check the bulkhead, ignition switch, and ammeter wiring. Re-seating is not doing it. Time to clean, tighten or change connector terminals. Packard 56 style terminals.
 
What do you do with the brown wire when you have removed the original ingnition system and installed an MSD disy and ICU? MSD recomended bypasing the ballest resistor.
 
73Swinger318 said:
What do you do with the brown wire when you have removed the original ingnition system and installed an MSD disy and ICU? MSD recomended bypasing the ballest resistor.
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Put blue and brown together.
 
67Dart273 said:
You may be on the right track, but what you say makes no sense. The dark blue is live "in run" so if it's not working, how could the car run?

The brown is live in start, so why won't the car fire in "start?"
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The way I understand his comments, the brown is hot in run.
Maybe neither wire is hot in start.
 
Well I think I figured out why my ignition cranks in start mode and starts in run mode.

When I check continuity between the battery (red) and the Brown (IGN2) in the run position I have continuity. When I place the car to start mode the IGN2 goes to open in continuity test. This would make sense why my car doesn't start when cranking but starts when the key goes back to run. Continuity test should show the opposite of what I have. In start mode the motor is turning over and over and over. When I let off the key for one brief moment the brown wire picks up the voltage while the motor is turning from the start and it fires. I've also noticed that every once in a while it just coughs or makes a small compression backfire. This I'm sure is caused when there's not enough rotation of the motor along with to much gas in the cylinders to fire the motor when the key comes back to the run position. I think this only make sense according to what I'm experiencing. The correct continuity is brown wire (IGN2) should be hot in start position and not be an open line.
 
Is there ANY chance that the blue/ brown got switched at the switch? Are you checking the switch while disconnected from the harness?
 
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