Not getting 12 volts to coil

[Mattax]

To test directly at the appropriate location in a circuit, do I insert a needle into the wire ?

For the locations with a plastic connector housing a thin probe into the back of the connector until it touches the metal terminal.

In most cases it doesn't need to be a super thin probe, just a standard one will generally do.
A couple of terminals have rubber on them to better seal against moisture. Usually R6 and A1 going into the firewall connector. So I usually skip those locations and go to the next nearest location.

On the column connector on your car, I'm not sure how much room there is to backprobe.

Begin with the easierto access locations.

Battery positive, Alternator output stud, Alt field J2 (backprobe).
Inside for the firewall connectors - although maybe on your car access is difficult - on mine its not (other than body mechanics!)

 

[wrecks]

For the locations with a plastic connector housing a thin probe into the back of the connector until it touches the metal terminal.

In most cases it doesn't need to be a super thin probe, just a standard one will generally do.
A couple of terminals have rubber on them to better seal against moisture. Usually R6 and A1 going into the firewall connector. So I usually skip those locations and go to the next nearest location.

On the column connector on your car, I'm not sure how much room there is to backprobe.

Begin with the easierto access locations.
View attachment 1715727086

Battery positive, Alternator output stud, Alt field J2 (backprobe).
Inside for the firewall connectors - although maybe on your car access is difficult - on mine its not (other than body mechanics!)

For the locations with a plastic connector housing a thin probe into the back of the connector until it touches the metal terminal.

In most cases it doesn't need to be a super thin probe, just a standard one will generally do.
A couple of terminals have rubber on them to better seal against moisture. Usually R6 and A1 going into the firewall connector. So I usually skip those locations and go to the next nearest location.

On the column connector on your car, I'm not sure how much room there is to backprobe.

Begin with the easierto access locations.
View attachment 1715727086

Battery positive, Alternator output stud, Alt field J2 (backprobe).
Inside for the firewall connectors - although maybe on your car access is difficult - on mine its not (other than body mechanics!)

Wrecks: now It's starting to make sense. I did not know about backprobing. You opened up a whole new world. Yes, I can get access to the column connectors. Measuring the current coming in and going out under crank should tell me if the switch is bad in both run and crank modes. My feeling is that the current will be less than 10.5 going to the ingition switch while cranking, which means cleaning/replacing the connectors, or checking the splice area. The two nuts holding the red and black ammeter wires look clean. I really appreciate your help. It makes me feel funny to take stuff apart under the dash that has not been moved since 1969.

 

[wrecks]

See the text above after Wrecks.

 

[Mattax]

My feeling is that the current will be less than 10.5 going to the ingition switch while cranking,

If the battery voltage is 10.5 Volts during cranking, that's fine.
One of the reasons the coil gets power through a wire direct from the key switch during start is the reduced voltage.

If the battery is at 11.5 Volts during start, and the feed to the column connection is 10.5 Volts, then there is resistance before the column connector.

 

[wrecks]

Since I got 1.5 lower volts after the bulkhead connecgtor under the dash than immediately before in the engine compartment, I'll work on cleaning them up or replacing. Frankly, nothing looks that bad. I see oxidation on the flat bottoms leading up to the fuses, but the copper looks ok.
So I bought some welding pins to try to clean the insides of the connectors out. Should I bite
the bullet and take the individual connectors out? As you said, I'll have to take the seats out
to make access easier.

 

[67Dart273]

Don't discount that the ignition switch CONTACTS themselves...............can be flaky/ intermittent/ unstable as to voltage drop

 

[wrecks]

That's really good advice. I'm going to try to get the black and red wires out and clean them. I see others have inserted a small screwdriver to squeeze the connectors together, and then they have pulled them out. I don't know where the 'female' connector is, but I'll see. Next,
I'll backprobe the steering column and fight that problem next.

 

[Mattax]

I'm not sure which terminals your working on, and I know some of the connectors on an e-body are different.
That said, it seems that most were one of the following"
Similar to Packard 56 and 58. The female terminalks have a tab to catch the plastic terminal.
Twin Lock.
Round terminals similar to Molex. Those are worth buying a removal tool for.

Skim through this 'till you find the ones that look like what you are working with.
Sources for Chrysler type wire terminals

This one too will has some pics pointing out the tabs/barbs for the Packard type terminals.
1969 Dodge Dart - Engine Compartment Main Bulkhead Connector

 

[wrecks]

I am assuming since I got low voltage at both ends of my ballast resistor when cranking, that my low voltage to the + coil was upstream- bulkhead or ignition switch. When I started looking at male/female connectors, they look good, so I tested resistance between red, black, brown, and yellow wire pairs at the front of the bulkhead and the corresponding column connectors on the steering column (wires going toward the engine, not up the steering column), and got close to zero for each wire. I did not want to remove these bulkhead male/female connectors as on a fishing expedition. So now I'm thinking about your comment about contacts on the cylinder switch. PS. My wife is making fun of me, because I told my son not to be afraid of surgery in school, especially if he specialized enough. She says I can't even
get my car to start.

 

[Mattax]

If there is no current flowing through the ballast resistor, voltage will be the same on both sides.
I do not know whether current wil lflow through the ballast during start, and if it does flow it may be intermittant as the coil resistance may be more lower than the combination of ballast (.7 ohms) and rotor winding resistance.

If there is any measureable resistance with an ohmeter, its probbaly too much. That's the reason for finding resistance using voltage loss with a known current. Also when using an ohmeter for small measureiment make sure you've zeroed the meter by touchiung the probes together and adjusting the meter or making note of the resistance.

review post #45.
I was avoiding the math at that time.
But this time lets include it.

We will measure voltage drop through any resistance between the battery positive and the main splice. We will measure voltage between the battery positive and the main splice by placing one probe on the battery terminal and the other on the alternator output terminal. No current flows through the R6 line as the engine is off. So the R6 wire acts as an extension of the probe.
Turning on the headlights will send roughly 12 amps from the battery to the main splice.

.15 V drop for 15 amps isn't bad.
Now lets do the math.
Energy level (Volts) = Current x Resistance.
0.15 Volts = 14 amps x R ohms
0.011 ohms = Resistance

(Example 2).
This time we're going to measure the resistance in the line between the alternator output and the main splice.
Engine running, battery fully charged, turn on headlights.
step 1. Start engine and allow battery to recharge. Ammeter shows zero. Measure voltage to ground from Alt output. It should be around 14 Volts.
step 2. Measure voltage difference between alt out and battery. Turn on headlights. Measurevoltage drop with lights on.

We're going to estimate the current knowing the only items drawing power are the lights, ignition, and alternator field.
At 14 Volts, the lights shoudl draw a little more current than at 12.5 V. 13 amps is reasonable estimate.
With points ignition at idle and low demand on the alternator, current for those may only be 4 amps.
Total of 17 amps flowing between the alternator output terminal and the mainsplice.
Voltage difference measures 0.9 V

0.9 Volts = 17 amps x R
0.053 ohms = Resistance.

What does 0.05 ohms in that line mean?
A couple things.
1) When the lights are on, there is so much resistance in the output line that the voltage regulator is seeing at less .9 Volts less than the alternator is putting out. If the regualtor is trying to keep the system running at 14.2 volts, then the alternator will have to be running at 15.1 Volts.
2) When more things are calling for power - things like wipers, brake lights, battery charging - then the current flow will be higher and the voltage loss even greater.
Also, voltage loss represents a loss of energy. Where did that energy go?
It goes to heat.

Once you know the resistance and condition of the two main power lines, then you can use the same method to check for resistance in the circuits going through the key switch.
On the other hand if you can measure resistance in any circuit or section of circuit with the ohmeter, then you know there is a problem. I dont see a need to do a voltage drop test to further prove anything.

 

[wrecks]

Mattax, I got 9 volts at the steering column connecter while cranking, but 10.5 on the other side in the engine bay for the same circuit by backprobing while cranking. Unless I had measurement error when I got '0' resistance 2 days ago in this same circuit, I don't understand. On your voltage drop test from the alternator to the spicle when the lights were on, I got 2.4 volts. (hey, at least my lights work, so at least part of the spice under the dash is o.k.). I could not do your other test, because my car won't start--at least due to low voltage to the coil, and I'm afraid to force a crank by hooking a battery cable from the battery + to the + coil. I have .45 volt drop at my negative cable to the negative battery post and .4 drop at my positive cable to the positive battery post.

 

[Mattax]

9 volts at the steering column connecter while cranking, but 10.5 on the other side in the engine bay for the same circuit by backprobing while cranking.

9 Volts backprobing which wire terminal on the steering column connector?
10.5 Volts backprobing where in the engine bay?

On your voltage drop test from the alternator to the spicle when the lights were on, I got 2.4 volts. (hey, at least my lights work, so at least part of the spice under the dash is o.k.)

Something garbled in the typing there!
I'll assume the measurement was from the battery positive to the alternator stud with output wire.
That shows there is a lot of resistance somewhere between the battery positive and the main splice.

To narrow that down further, move the probe to the starter relay connection, and then to the fusible link connection if its not sealed. I'm not sure what's on your car.
It would not surprise anyone if there was some deterioration in cavity 16 of the bulkhead connector, but sometimes its a bad connection at the battery cable or something else.

I have .45 volt drop at my negative cable to the negative battery post and .4 drop at my positive cable to the positive battery post.

Let me be sure I understand. When the headlights were on, one probe on the top of the lead terminal and the other probe into the cable's terminal?
If so, the .4 Volts is a portion of 2.4 Volt drop between the battery and the main splice.

Unless I had measurement error when I got '0' resistance 2 days ago in this same circuit, I don't understand.

Because the resistance is at the lower limit of what most multimeter's can measure.
Resistance caused 2.4 volts to be lost when 12 amps was put through the line.
2.4 Volts divided by 12 amps
That's 0.2 Ohms

 

[wrecks]

9 Volts backprobing which wire terminal on the steering column connector?
10.5 Volts backprobing where in the engine bay?


Something garbled in the typing there!
I'll assume the measurement was from the battery positive to the alternator stud with output wire.
That shows there is a lot of resistance somewhere between the battery positive and the main splice.
View attachment 1715733810

To narrow that down further, move the probe to the starter relay connection, and then to the fusible link connection if its not sealed. I'm not sure what's on your car.
It would not surprise anyone if there was some deterioration in cavity 16 of the bulkhead connector, but sometimes its a bad connection at the battery cable or something else.


Let me be sure I understand. When the headlights were on, one probe on the top of the lead terminal and the other probe into the cable's terminal?
If so, the .4 Volts is a portion of 2.4 Volt drop between the battery and the main splice.



Because the resistance is at the lower limit of what most multimeter's can measure.
Resistance caused 2.4 volts to be lost when 12 amps was put through the line.
2.4 Volts divided by 12 amps
That's 0.2 Ohms

 

[wrecks]

Yes, the wire with 9 volts under the dash and 10.4 in the engine bay was #16. # 18 (black) was confusing, as it seemed to go to 0 under cranking. All my fuses look old but unblown, except the extentions for the red and black wire coming into the box are exposed on top- with nothing over each one's stud sticking out. Yes, I did the voltage drop test from the alternator 'batt' post, and I assume I'm measuring the positive part of the under dash splice circuit, because if I were drop testing the negative part of a circuit , would I have the negative volt meter terminal on the alternator's body's metal body and the positive meter terminal on the battery's negative terminal? You've given me a lot of principles and clues. My car is supposed to be stock, but we were supposed to be virgins on our wedding night. The alternator is original, but a shop said it was good. I'm surprised we have not talked about the two connections on the ammeter gauge, but I'm glad, even if you may be testing me to develop a test that would infer something about the ignition switch, my demon problem. Thank you for helping me. # 16 is on the bottom of my bulkhead connector, but in the manual, all the connections look upside down.

 

[Mattax]

Let's start with this.

Yes, I did the voltage drop test from the alternator 'batt' post, and I assume I'm measuring the positive part of the under dash splice circuit, because if I were drop testing the negative part of a circuit , would I have the negative volt meter terminal on the alternator's body's metal body and the positive meter terminal on the battery's negative terminal?

Yes. You can measure for resistance in the grounding with one probe on the battery negative terminal and the other probe on some other ground point. For the headlights, I would probably chose the screw where the headlight wires ground to the radiator support.

the wire with 9 volts under the dash and 10.4 in the engine bay was #16.

let me get this correct.
While someone is turning the key to start, one probe is in the firewall connector at 16?
I'm just a little surprise because that is often sealed making it hard to backprobe.
Same with wire R6 into cavity 18 - the ones I've seen (A-body) are sealed.

# 18 (black) was confusing, as it seemed to go to 0 under cranking.

Are you talking about R6 wire ? The one connected to the alternator?
or are you talking about Q2 on the steering column ?

If R6 is going to zero during start, something is wrong.
If Q2 is goin gto zero during start, that is correct.

 

[Mattax]

here's the seal I'm talking about

 

[Mattax]

I'm surprised we have not talked about the two connections on the ammeter gauge, but I'm glad, even if you may be testing me to develop a test that would infer something about the ignition switch, my demon problem.

So. Yes the tests are to isolate and narrow down the problem.
What this one shows is there is resistance in the highlighted path.

I'm trying to understand where the probes were on this one, and was this also during the headlight on test.

I have .45 volt drop at my negative cable to the negative battery post and .4 drop at my positive cable to the positive battery post.

Is this where the probes were?

If so, then that is one step closer to identifying the location(s) of resistance.

Then check the first section (because its easy)

What you check next depends on a what you can access.
For example, you have long wire leads or maybe an aligator clip and some long wire, I've done this.

It can also be done by using the ground as reference. Use the same ground for both positions. Or at least what should be the same, like the body sheet metal.

Compared to inside.

IF you find the 2.4 voltage drop is all in the sections just tested, then there is no reason to access the more difficult to reach ammeter connections.


There may or may not be poor connections in the ignition switch, its connector, or the firewall connectors. What we are seeing is there is a significant issue before the electricity gets to the column connector or fuse box. We can't use the battery as a reference for testing when the votlage is dropping before it even gets to the main splice.

 

[wrecks]

So. Yes the tests are to isolate and narrow down the problem.
What this one shows is there is resistance in the highlighted path.
View attachment 1715734196

I'm trying to understand where the probes were on this one, and was this also during the headlight on test.


Is this where the probes were?
View attachment 1715734241

If so, then that is one step closer to identifying the location(s) of resistance.

Then check the first section (because its easy)
View attachment 1715734246

What you check next depends on a what you can access.
For example, you have long wire leads or maybe an aligator clip and some long wire, I've done this.
View attachment 1715734249

It can also be done by using the ground as reference. Use the same ground for both positions. Or at least what should be the same, like the body sheet metal.

View attachment 1715734253

Compared to inside.
View attachment 1715734255


IF you find the 2.4 voltage drop is all in the sections just tested, then there is no reason to access the more difficult to reach ammeter connections.


There may or may not be poor connections in the ignition switch, its connector, or the firewall connectors. What we are seeing is there is a significant issue before the electricity gets to the column connector or fuse box. We can't use the battery as a reference for testing when the votlage is dropping before it even gets to the main splice.

 

[wrecks]

Yes, Q2 went to 0 on start under the steering column. Here are some results with your lights on to draw some current at the splice under the dasht:
R6 at Batt on alternator to splice had 1.7 volt loss one time and .7 another. ??
Red wire under column connector 11.6 volts with ground to body.
Red wire at bulkhead (with insulation puncture) had 11.58 volts with ground to body.
Red wire under column connected to + battery had .89 drop.
Red wire (# 16) at bulkhead connected to + battery had .14 drop.
fusible link had .57 loss with lights off and voltmeter to + battery and .27 with lights on.
I don't understand how the voltage readings to gound were so close before bulkhead and after bulkhead, yet the voltage drop differences were so high. Should the horn be loud?

 

[Mattax]

Not sure what's happening with your quotes and replies.

I'm going to try to merge them so to make sense to myself.

What works on a computer is to highlight the sentence you want to quote by holding the mouse button down over all the text of interest. Release the mouse button and there will be two choices. For jsut one quote, click reply. For multiple quotes, click quote.

Here's a screen shot.

Then when typing into the reply box, click the "Insert Quotes" button will let you chose one or more of the quotes you selected.

Is this where the probes were?

If so, then that is one step closer to identifying the location(s) of resistance.

Then you can place your answer or question to each section like I think you are trying to do.

 

[Mattax]

Are you talking about R6 wire ? The one connected to the alternator?
or are you talking about Q2 on the steering column ?

Yes, Q2 went to 0 on start under the steering column.

That is working correctly.
When the key is in start, the switch only connects the Battery to J2A (ignition start) and S2 (starter relay)

 

[Mattax]

I don't understand how the voltage readings to gound were so close before bulkhead and after bulkhead, yet the voltage drop differences were so high.

We'll have to add them up and see. It is possible that something is loose. And its possible that byt probing a loose terminal you temporarily made the connection better.

We can only add up what was measured under the same conditions. If the battery is not being recharged after each test, this will result in some decrease of both voltage and current flowing.
Anyway kets give it try with what you've measured.

lights on to draw some current at the splice under the dasht:
R6 at Batt on alternator to splice had 1.7 volt loss one time and .7 another. ??
Red wire under column connector 11.6 volts with ground to body.
Red wire at bulkhead (with insulation puncture) had 11.58 volts with ground to body.
Red wire under column connected to + battery had .89 drop.
Red wire (# 16) at bulkhead connected to + battery had .14 drop.

Does this look like what you measured with lights on?

This is showing a small drop in voltage up to the bulkhead connector, and essentially no drop in voltage (.02V) between the bulkhead connector and the main splice.
We don't have a battery voltage measurement during this test, but if we add 0.7 to 11.6 Volts measured inside the passenger compartment, that's 12.5 Volts.
12.5 Volts acros the battery makes sense.
Sure seems like there is enough resistance in the bulkhead connection to cause trouble.

fusible link had .57 loss with lights off and voltmeter to + battery and .27 with lights on.

This I can't help with.
Unless there is a clock or something, there should be no current flowing through the fusible link with the everything off.
Wait. Maybe the door was open and the dome light on?
Still current would increase with the lights on. Possibly a loose connection at one or both ends of the fusible link ?

 

[Mattax]

Should the horn be loud?

In the garage? Yes.
Horn wiring changed a lot from year to year and model to model. We need to find where the relay power is wired in for your car to even begin looking.

 

[wrecks]

Is this where the probes were?

I separated each battery cable from each battery post; for the positive cable, I put the + volt lead on it, and I put the - volt meter lead on the + battery post, and recorded the result. I replaced the positive cable on its post, and reversed the process for the negative battery post.

 

[wrecks]

Thank you for showing me some basic skills. Because resistance was higher on the other side of the bukhead connector for the # 16 wire, I think I'll pull out the # 16 blue female pin, and others, if needed inside the bulkhead, clean them, and see if voltage to the + coil has increased above 9 volts, when I try to start the car. Turning on the lights was a good idea, because you got some current flowing to test concepts, and I appreciate the concept of checking the 'distant' splice by inference from a wire that is asleep with lights on.