Fried ECM
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wot440
Active Member
Coil @1.8 200ohms setting
9.0 20K ohms setting
I Have two new ballast resistors both read same. 1.5 then drops to 0.9
With key on:
Battery 12V
Start side of ballast(blue wire from bulk) 10.6V
Run side of ballast (brown wire) 8.0
9.0 20K ohms setting
I Have two new ballast resistors both read same. 1.5 then drops to 0.9
With key on:
Battery 12V
Start side of ballast(blue wire from bulk) 10.6V
Run side of ballast (brown wire) 8.0
wot440
Active Member
After market 4 pins. blue box, Timing set 12* btdc, manual choke open.
Appreciate you guy's help. I know these things can be a pain in the butt.
One other thing I can add is... after it dies, it will crank with no spark, and spark at the release of the key and fire for a second then die.
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Should be 0.5 to .7 Ohms at air temperature.
12.0 to 10.6 V is a big drop between the battery and the ignition wire. Check every terminal and connection.
Run side is almost always Blue.
Coil/Start side of ballast should be lower when current is flowing, so that's OK.
Schematic is like this. Feed wire to ignition switch may be red insulated in your car and year.
Here's your test.
When the current flows through the resistor, it loses Voltage. So that's OK.
But when the current flows through the circuit, it should not be losing any voltage.
In reality, there is resistance. Depending on the current draw, a half volt might be acceptable.
1.7 Volts with only 4 or 5 amps draw indicates a problem.
When the engine is running, current should be flowing from the alternator.
If there is bad connection on that wire, that would heat up and get worse as it runs.
You can do a visual check on the connectors and terminals.
A search here for Packard 58 and Bulkhead connectors will turn up photos for you.
wot440
Active Member
Thanks Mattax, appreciate your help. I will check connections and wires. I'll start with the voltage drop. And go from there.
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67Dart273
Well-Known Member
For the record, 14.5 is not "way high." The spec when warm used to be 13.8--14.2. So nominal 14V. 14.5 won't hurt anything electrical, it likely begin to make the battery "use water"
67Dart273
Well-Known Member
The only difference in the circuit / ECM with the dual ballast is that the second ballast resistance feed power into the 5th pin on the ECU. That is no longer used, and unless you find a really old original vehicle or really old NOS, most any new ECU WILL be 4 pin.
You can use a 4 pin box in a 5 pin harness, but not the other way around
Incidently, the "single" (or other half) of the ballast is the same exact circuity/ wiring as the old points setup. In fact in an emergency, if the thing quits, you can stuff in a breaker point dist. hook the wire to the coil, unplug the ECU and go
In today's Chineseoficianicated products, hard to say, but ECUs usually don't fail that often
You can use a 4 pin box in a 5 pin harness, but not the other way around
Incidently, the "single" (or other half) of the ballast is the same exact circuity/ wiring as the old points setup. In fact in an emergency, if the thing quits, you can stuff in a breaker point dist. hook the wire to the coil, unplug the ECU and go
In today's Chineseoficianicated products, hard to say, but ECUs usually don't fail that often
Voltage exists when there is no current.
So the first two voltage measurements have nothing to do with grounds.
Whatever the battery positive is connected is at battery voltage.
Think of it this way. Turn off all the faucets in the house, there's still 60 psi or whatever your pump/city provides in the lines.
The mysteries are:
a) Why is there voltage at those test locations with the switch off? (that's what 67Dart273 stated above, just restating it here)
b) Why is there a voltage drop ignition wire.
Seeing 12 V on both sides of the Voltage regulator makes sense. When there is ony 12 Volts at the regulator, the upper points stay closed so maximum current can flow through the rotor.
Where is the power wire for the ECM spliced in?
wot440
Active Member
Right now it is dis connected. (12v when checked to bat pos.) It was connected to the run side of the ballast resistor.
OK.
A couple suggestions.
But first, forgive me if you already know this, lets be sure the measurements are what we think.
When its not zero, we're measuring votlage drop from resistance to flow.
On the other hand, when one test lead is placed on the negative terminal, whatever the second lead touches is voltage above ground.
Voltage above ground is the normal assumption when not otherwise specified.
My first suggestion is to visually trace the wires on your car and make sure they are routed correctly and the terminals look good.
You can copy the schematic and either print it out or open it in MS Paint.
Check the wire colors and connections in my schematic against the factory service manual wiring diagram for your car and year. Each car and year is a little different.
Then you can do voltage checks if and see if they make sense for the circumstances.
When testing, check the ammeter as this will show whether current is flowing out of the battery (or into it for recharging).
A couple suggestions.
But first, forgive me if you already know this, lets be sure the measurements are what we think.
When one of the test leads is on the battery positive terminal and the second lead is placed any point connected to the positive, the voltage should be zero.
When its not zero, we're measuring votlage drop from resistance to flow.
On the other hand, when one test lead is placed on the negative terminal, whatever the second lead touches is voltage above ground.
Voltage above ground is the normal assumption when not otherwise specified.
My first suggestion is to visually trace the wires on your car and make sure they are routed correctly and the terminals look good.
You can copy the schematic and either print it out or open it in MS Paint.
Check the wire colors and connections in my schematic against the factory service manual wiring diagram for your car and year. Each car and year is a little different.
Then you can do voltage checks if and see if they make sense for the circumstances.
When testing, check the ammeter as this will show whether current is flowing out of the battery (or into it for recharging).
wot440
Active Member
Switch has been replaced one year ago.
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Schematically it should be like this. If not, mark it up.
The solid black dot is a welded splice wrapped in electric tape. Leave it alone.
Adding a third wire to that terminal connection should work. Honestly its not a great way to do it.
I'd either piggy back it there with one of these
Splice it in permanent or attach it at the regulator.
I think there is one year where some ignition wires goes to regulator first. Only you can say what you have there.
The solid black dot is a welded splice wrapped in electric tape. Leave it alone.
Adding a third wire to that terminal connection should work. Honestly its not a great way to do it.
I'd either piggy back it there with one of these
Splice it in permanent or attach it at the regulator.
I think there is one year where some ignition wires goes to regulator first. Only you can say what you have there.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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Nice work Del
Jus saying; My Orange box survived 18 volts when my fancy regulator failed in full fielding mode. Ima thinking she ran like that for about 30 minutes.
Jus saying; My Orange box survived 18 volts when my fancy regulator failed in full fielding mode. Ima thinking she ran like that for about 30 minutes.
wot440
Active Member
OK Thank you. I will print these out and check these connections off one at a time.
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Thanks Matt and Dell had to run out yesterday. From what I am reading definite V drop to the ballast resistor. You guy are great.
wot440
Active Member
Thanks to all for the tremendous amount of help received yesterday. My plan for today is to finish unraveling fifty years of electrical tape and expose every wire and connection in the engine compartment. Then one by one inspect clean and check resistance and voltage for each. Once this is done I will move to the other side of the bulk head connector and do the same. I noticed the starter relay to starter wires are fifty years old and are not in the greatest shape, so those will be replaced but not until the problem is found. Also I will get a new ing. switch from NAPA to replace the auto zone switch. (which I do not have much faith in) again not until the problem is found. Thanks again to all who have been kind enough to lend assistance.
It's hard to know what you'll find until you look. My current car came from the desert - a lot of dried out insulation etc in the engine compartments hottest locations etc. Under the dash and inside is still pretty good. I installed a replacement engine harness and after 20 years or so, some terminal connections were failing and I've had to replace them.
One possibility to look out for on the ignition switch is its for a different year/model.
They shouldn't physically interchange but maybe they can????
From 68 to 69 Abodies the Ignition 2, Accessory, and Start wires connect to different switch terminals.
Why do 68 & 69 dart iginition switches have different # ground plug ins?
[SOLD] - nos mopar ignition switch
The bulkhead connector could have a bad connection, not sure if anyone mentioned this or not. All this talk about the ballast resistor.... I don’t use them with electronic ignitions, I have ran several vehicles for years without them.
wot440
Active Member
Just realized I mis stated info. In one of my post I stated start side of ballast as being blue and run side brown. Actually it is the opposite. Start side brown @ 11.2v up from 10.6 after cleaning bulkhead connectors. Run side blue. Apologize for adding confusing.
Sounds like you're making some progress.
Start side is also coil side, so when the key is in run and the points are closed then current will be running through the coil.
With an ECU hooked up instead of points, current will flow through the coil when the key is on.
If you unplugged the ECU's pentagram shaped connector, then no current can flow through the coil.
Lets go over the voltage drop testing.
Key off, nothing turned on, door shut so the dome light is off, no current flows.
Checking for voltage simply shows which wires are hot.
Lets say the battery is fully charged and voltage from positive to ground is 12.8 volts.
Same situation, turn the key on with the ECU disconnected.
Why are there voltage drops?
Why might there be a little ammeter movement?
Its because the voltage regulator is seeing less than 14 Volts, so its allowing current to flow through the alternator's rotor.
The ammeter movement will be very small because its only around 2 amps. A little more or less depending on which alternator is installed.
The voltage drop illustrated in this example shows resistance in every push type connection that causes a 0.1 Volt drop for every 2 amps.
Think about that.
Voltage drops where current flows through resistance.
Same drawing with arrows showing flow path.
Increase the current through a resistance and there will be more voltage loss.
The dash ammeter scale goes from 40 amps discharge to 40 amps charging.
Its good enough to see movement in the needle with 4 or 5 amps flowing through.
Notice it is positioned only to show battery charging or discharging, not alternator output.
67Dart273
Well-Known Member
You can easily "hot wire" the ignition to see if it will run. One way is to pull the blue field wire off the alternator and run battery power TO it. It should be spliced into the ignition. Another place is to figure a way to jumper power into the ballast where it is jumpered together. That is, two of the 4 ballast terminals should be jumpered together.
So far as losing voltage, the functional path is battery.........starter relay "big stud", fuse link, through the bulkhhead on the big red ammeter wire
Through the ammeter, out the blg black ammeter wire, the welded splice, branch offf to the fuse panel "hot" bus and to the igntion switch.
Through the switch, out on "ignition run" usually dark blue, back out through the bulkead, and at some point branch off and feed the ignition system, the VR, some smog equipment if used, and the alternator field
So the main points to check are the big red and big black going through the bulkhead, the ignition switch and it's connector, and the dark blue feeding back out into the engine bay through the bulkhead
So far as losing voltage, the functional path is battery.........starter relay "big stud", fuse link, through the bulkhhead on the big red ammeter wire
Through the ammeter, out the blg black ammeter wire, the welded splice, branch offf to the fuse panel "hot" bus and to the igntion switch.
Through the switch, out on "ignition run" usually dark blue, back out through the bulkead, and at some point branch off and feed the ignition system, the VR, some smog equipment if used, and the alternator field
So the main points to check are the big red and big black going through the bulkhead, the ignition switch and it's connector, and the dark blue feeding back out into the engine bay through the bulkhead
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