Sure. Glad to be have some help.
This link in the earlier post should help with seperating the connectors and removing terminals.
1969 Dodge Dart - Engine Compartment Main Bulkhead Connector
and
question on the main harness plug on firewall
Not getting 12 volts to coil
- Thread starter Dusten
- Start date
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This link in the earlier post should help with seperating the connectors and removing terminals.
1969 Dodge Dart - Engine Compartment Main Bulkhead Connector
and
question on the main harness plug on firewall
This information on getting the pins out is invaluable. I'm going to have another practicle hurdle, but on my low voltage problem, I don't understand why, with the lights on, the voltage in front of the bulkhead at the 16 red wire location and the corresponding path inside the car under the steering column had such high, and almost identical voltages of 11.58 and 11.60, but the voltage drop tests applied at the same two points with the negative end of my meter at the + battery terminal, showed high resistance under the steering column , 89 volt, and low resistance at the bulkhead, .14. Could it be that the splice captures other paths not used with the lights on, like ignition, and fuse box, which could expose hidden resistance?
I'm going to assume your digital meter doesn't care which probe you place on the higher voltage location. If reversed the meter will just show negative.
Now I'm not quite sure what you did.
This what I thought you described.
So I assumed the battery voltage to ground was around 12.5 Volts.
And that's why I concluded there was resistance in the bulkhead connection.
Probably best to measure the battery voltage with the lights on.
Comparing voltages to ground is OK, but assumes the ground path is perfect.
Check the ground path by turning on the lights and measuring from the battery negative post to some body ground locations.
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Seperately - I meant to write this before. Not related to the bulkhead but is related to your initial question.
If you want to do a check of the ignition switch to see if its a major source of resistance, you can check the operation with the ohmeter.
-Disconnect the steering column connector.
- Measure on the switch half from the J1 (power in) to the Ignition, Accessory and Start terminals. Should be no connection.
- Turn key to Accessory. Measure from J1 to the other terminals. Q2 should have no resistance and the Ignition Run (Dark Blue) should be open.
- Turn key to Run. Measure from J1 to the other terminals. Q2 and Ignition Run (Dark Blue) should have no resistance. Start and Ignition (Brown) should be open.
- Turn key to Start. Measure from J1 to the other terminals. Q2 and Ignition Run (Dark Blue) should be open. Start and Ingiton Start (brown) should have no resistance.
When done, touch the meter probes together to see what the 'zero' resistance reading is. It might be 0 or it might be .1 ohms
If any of the connections showed above the baseline zero of the meter, there may be resistance of consequence in the switch.
Now I'm not quite sure what you did.
This what I thought you described.
So I assumed the battery voltage to ground was around 12.5 Volts.
And that's why I concluded there was resistance in the bulkhead connection.
Probably best to measure the battery voltage with the lights on.
Comparing voltages to ground is OK, but assumes the ground path is perfect.
Check the ground path by turning on the lights and measuring from the battery negative post to some body ground locations.
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Seperately - I meant to write this before. Not related to the bulkhead but is related to your initial question.
If you want to do a check of the ignition switch to see if its a major source of resistance, you can check the operation with the ohmeter.
-Disconnect the steering column connector.
- Measure on the switch half from the J1 (power in) to the Ignition, Accessory and Start terminals. Should be no connection.
- Turn key to Accessory. Measure from J1 to the other terminals. Q2 should have no resistance and the Ignition Run (Dark Blue) should be open.
- Turn key to Run. Measure from J1 to the other terminals. Q2 and Ignition Run (Dark Blue) should have no resistance. Start and Ignition (Brown) should be open.
- Turn key to Start. Measure from J1 to the other terminals. Q2 and Ignition Run (Dark Blue) should be open. Start and Ingiton Start (brown) should have no resistance.
When done, touch the meter probes together to see what the 'zero' resistance reading is. It might be 0 or it might be .1 ohms
If any of the connections showed above the baseline zero of the meter, there may be resistance of consequence in the switch.
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Yes, I penetrated the insulation at the bulkhead for position # 16 for wire A1 10R and got 10.5 volts, but only 9 volts at the column connector (backprobe), wire J1 12 R.
Going back to your schematic at post 80, Yes, your drawing reflects what I did. Both battery voltages to ground were within a few minutes of each other, and the voltage drop tests were done with the both the headlights and interior lights on with the negative volt meter terminal on the positive battery terminal. The increased implied resistance using both your 'lights on' test and my earlier cranking tests are what have led me to check the male and female bulkhead pins before messing with the ingition switch.
Ok. If the seal you pierced is the one on the engine side of the firewaull, then it makes sense.
If you probed on the passenger compartment side of the firewall, then the resistance might be at the ammeter connections.
On the older A-body's and others that use the same firewall connector, backprobing the inside is fairly easy. On your car I don't know.
I think what you've done so far points in that direction.
Once the connector is seperated ypou can see the condition of the terminals.
Decide your next steps from there.
Dont feel bad. I'm tracking down an issue on my '85 Grand?Wagoneer. The fusebox is mounted directly on the inside of the bulkhead connector making it impossible to backprobe the main connections. Plus it has the A/C that hangs under the entire length of the dash. A royal pain for that and other reasons.
Mattax, you have really helped me learn, and I have led an 'isolated life.' At 72, I'm lucky my car has bench seats and column automatic (70 'Cuda -sorry). But the stretching and weird angles seem to have helped me in other areas of life. It may be a while before I reply. other problems at home.
I've been out of town, and am using DeOxit to reduce resistance on the red terminal going to the fuses, which only goes close to zero when I put pressure on it. On the ingintion switch tests you mentioned, I get 1 resistance (bad) on J1 and Q2 with the key in 'accessory' (first click), but 0 when the key is turned to 'run' , second 'click. I'm still trying to clean the red and black basic connections from the ammeter gauge. My car is stock.
I'm not understanding what red terminal to the fuses you are pushing on.
You'll have to correct me if there was a change for your car.
On everything I have, the accessory position is the other direction from on and start.
So I think your switch is OK so far
p2. 1975 Operator's Manual Plymouth Valiant
Speaking of which, you'll have to say what wire is actually where on your car. The Shop manual shows Ignition 1 as the brown wire on that connector. Elsewhere (and on other drawings) Ignition 1 is the Run wire and is blue or blue with a stripe. Ignition 2 is start. Lets just call them Ign run and Ign Start. Ign Run is almost certainly the blue wire.
So make note or photo what is actually on the car..
??
You'll have to correct me if there was a change for your car.
On everything I have, the accessory position is the other direction from on and start.
So I think your switch is OK so far
p2. 1975 Operator's Manual Plymouth Valiant
Speaking of which, you'll have to say what wire is actually where on your car. The Shop manual shows Ignition 1 as the brown wire on that connector. Elsewhere (and on other drawings) Ignition 1 is the Run wire and is blue or blue with a stripe. Ignition 2 is start. Lets just call them Ign run and Ign Start. Ign Run is almost certainly the blue wire.
So make note or photo what is actually on the car..
67Dart273
Well-Known Member
Forget checking this stuff with resistance checks other than a 'quick' check for continuity. Check them under load, and check them for voltage drop. That is the ONLY way you are going to find drop problems, because poor connections or high contacts resistance in switches changes under load
I agree. I just suggested it as a way to quickly identify if there was major resistance in the switch or its leads.
Mattax, Below is the J1 big red wire, which looks pretty clean (used DeOxit) and conducts over 11 volts with interior lights on and aligator clips from its male bulkhead connector to this female connector. The next picture is the fuse box J1 red wire, which also gets 11 + volts by touching the connector and grounding to the steering column. All your ignition switch tests worked except the two with the key in start and the J1 to -Q2 (Accessory and J1 - to J2A (ignition 1), which were closed, and the other pairs, J1 to S2-18Y (start) and J1 to J3 and J1 to Ignition 2, were open. But when you say 'start', do I keep pressure on the ignition switch? Maybe that's my problem.
I'll pull the female black Accessory Q2 wire and look for corrosion. The connections to the individual fuses look the worst, although I got closed results with testing
each pair for continuity. The second picture is the place where these fuses hook up. The fuse box disconnects from the female connector box. Thank you for guidance on the theory of voltage drop, and results varying with the load on the whole circuit. Also, the ignition tests were really neat, especially since you can do them with no current flowing.
I'll pull the female black Accessory Q2 wire and look for corrosion. The connections to the individual fuses look the worst, although I got closed results with testing
each pair for continuity. The second picture is the place where these fuses hook up. The fuse box disconnects from the female connector box. Thank you for guidance on the theory of voltage drop, and results varying with the load on the whole circuit. Also, the ignition tests were really neat, especially since you can do them with no current flowing.
I'm too tired to read and look up stuff and not make mistakes.
A couple things I can answer now.
Not sure what you mean by J1 at the fuse box. [edit: rereading now I think I understand now, see new post below.] I'll look at the shop manual diagram for e-body.
Generally I've seen
J1 is from the main splice to the ignition switch.
Q2 is out from key switch to junction and then to the fusebox as Q2A.
Q3 is from main splice to fuse box.
The fuses connected to the Q2A wire are only hot when the key is in Accessory or Run.
The fuses connected to the Q3 wire are always hot.
(Wire H1 is also hot at all times. It connects to the horn relay.)
Its fine to clean up the connections at the fusebox.
But nothing there would relate to lower voltage at the battery and/or the regulator than compared to alternator.
A couple things I can answer now.
Yes.
Not sure what you mean by J1 at the fuse box. [edit: rereading now I think I understand now, see new post below.] I'll look at the shop manual diagram for e-body.
Generally I've seen
J1 is from the main splice to the ignition switch.
Q2 is out from key switch to junction and then to the fusebox as Q2A.
Q3 is from main splice to fuse box.
The fuses connected to the Q2A wire are only hot when the key is in Accessory or Run.
The fuses connected to the Q3 wire are always hot.
(Wire H1 is also hot at all times. It connects to the horn relay.)
Its fine to clean up the connections at the fusebox.
But nothing there would relate to lower voltage at the battery and/or the regulator than compared to alternator.
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I think what you're calling J1 is all of the wires that are connected to the welded junction.
With that out of the way, we can probably figure out what you measured.
Even with the photo I don't understand where this femal terminal connected.
Remember the question is whether its less than the supplied voltage while the current is flowing. If the battery is the same 11+ Volts with the lights on, then there is not any resistance to that amount of current along that path.
The goal is to find where there are poor connections or bad wires. If it looks bad, or feels loose, just clean it and gently tighten it up if you can.
That arrangement is one I haven't worked with. Hopefully there is enough slack its not too difficult to deal with.
Thank you, Mattax for all your help. I've never seen most of your diagrams, which I need to study and combine with your insights. My whole assumption was a low voltage from the two-wired end of the ballast resistor meant my problem was bulkhead connector, splice, ammeter connections or the steering column switch. I've looked at wire # 16's cavity (red) male and female connections in the bulkhead connector and plan to do the same thing with cavity # 18 black wire, because they seem to be the basis for everything else related to low voltage at the ballast resistor, which would reflect as low voltage to the + coil. I lack knowledge of how the relevant wires flow and work together. After I try to clean the male/female # 18 wire, I'll reasseble. If it fails, then I'll have to decide if I want to learn how to install new connectors. The wires at the ammeter gauge look clean, but I've never looked at the splice. There seemed more current going into the bulkhead # 16 (I've cleaned the male probe) than coming out- see the female # 16 connector picture, so that's my hope. If that fails, maybe I'll pack up and move to Florida.
My diagrams are essentially tracings of the circuits of interest. They are from the same shop manual as you are looking at. Just reorganized a bit so its easier to see the flow.
Making a schematic like these is helpful in visualizing how the circuit connects and works.
Here's a pdf you can download from 1968 where Chrysler suggests this https://www.mymopar.com/downloads/mtsc/247.pdf
I Agree that those are the most likely places where there could be resistance. The battery terminal and the terminals at the relay and fusible link are also possibilities.
The tests I was suggesting were designed to narrow down the list, and avoid digging into areas that are difficult to access if not neccessary.
Lets just go over the strategy.
1. Make sure the battery is fully charged. I assume you have some sort of charger whether automatic or manual.
2. Check for resistance in each power feed to the main junction.
2a Measure voltage drop between the battery terminal and the main junction with some moderately high current (engine off).
2b Measure voltage drop between the alternator terminal and the main junction with about the same current (engine running).
3. After establishing or correcting so there is minimal resistance in fees to the main splice, then check for voltage drops between the main splice and the ballast resistor.
3a. Resistance check of the key switch will identify a major issue there.
3b. Measure voltage drop between the battery positive and the ballast resistor, and the battery positive to the cavity in the firewall connector. Then you'll know if the problem is inside, or in the engine compartment.
Yes. 16 connect the battery feed wire (A1-12red) and 18 connects the alternator output wire (R6-12 black)
Might as well look at and clean terminals for J2 and J3 wire while your in there.
Unless the evidence points to a bad welded splice, there's no reason to unwrap the tape to look at it.
Current in must equal current out. Picture it like a stream except instead of gallons per minute its electrons per second.
It is the voltage that is reduced when current goes through resistance.
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Lets look at the two wire junction on the resistor for a '70 Barracuda:
When Starting, voltage at that terminal should be the same as the battery voltage. If the battery drops to 11 Volts during starting, then the voltage at that side of the ballast resistor should be 11 volts. If its 9 Volts at the battery, it should be 9 volts at the ballast connection.
During start, only about 5 amps flows from the junction at the starter relay to the starter switch, where it divides into two smaller currents. There should be no resistance to that flow.
When the engine is running, voltage at the ballast resistor's two wire junction should be less than at the single wire terminal.
Voltage at the single wire terminal should be the same as the power supply voltage.
Why?
With the key in run, current to the coil and points must flow through the ballast resistor. Current flowing through resistance loses voltage. When the coil sees less voltage, it draws less current. Together this provides the correct amount of electricity for the coil to function as designed.
If we want to know what voltage the regulator sensing terminal is seeing, we need to measure the at the ballast resistor's terminal with the single blue wire. Another place to check is at the alternator's blue wire field terminal connection.
I'm waiting for a cleaning chemical to arrive, and reading your wiring basics, 1968 article. All your ignition switch tests worked. What a relief. Thank you. I should have figured them out myself. All I want is 1 volt more at the +coil. After the bulkhead male/female cleaning, if it does not work, I'll follow your plan for voltage drops in the engine bay. I have an original 1970 alternator, which a took to a starter shop and they said was good. New starter, coil, dual points, rotor, ballast resistor, plugs.
In tracing wires back to wiring diagrams, I found out my car has the wiring for a different engine, so I'm sort of in shock and that that bulkhead cleaning for 1 extra volt doesn't matter anymore. There's actually two modules of six wires each (including the dark blue wire to the + coil), I don't even have.
Can you explain more? Post pics?
In the shop manuals there are diagrams for rally dash equiped cars and a seperate set for non-rally dash cars. The bulkhead connectors are different.
I'm not familiar with the e-body wiring and how things were done differently for different options.
The only wiring diffferences we see in the shop manuals due to engine options is generally for the 426 Hemi cars.
It is completely possible there are errors or undocumented options in the shop manuals.
For example there's at least two or three threads here at FABO about undocumented windshield wiper motor wiring for the 1967 cars.
I can't find the rectangles in the photo. My bulkhead looks like other ones I see for sale online. This picture if from the wiring diagram for a Hemi. The other wires, colors, look the same- like with the ballast resistor, but I can't find the [1.2.3], [4,5,6].
OK. I'm sure we can figure this out. May need to look at some unmolested or well restored examples, but lets try with what we have now.
Your 1970 Barracuda originally came with what instrument panel and options ?
Let me clip some pics for my own better understanding of the options.
or
This is your photo of the inside of the bulkhead connector. We see a pair of 4 terminal connectors and a pair of 8 terminal connectors.
which looks like it matches up with this illustration in the Plymouth FSM
So far so good. Now I'm looking at the engine compartment diagrams. In addition to the alternator wiring for the Hemi that you posted, the diagram on the previous page shows four or five wiring configurations depending on the engine and whether an idle speed solenoid was used. None of these use a a connector like the Hemi wiring.
Is there, or was there a idle soldenoid on the throttle side of the carburrtor. Take a photo if it helps.
Your 1970 Barracuda originally came with what instrument panel and options ?
Let me clip some pics for my own better understanding of the options.
This is your photo of the inside of the bulkhead connector. We see a pair of 4 terminal connectors and a pair of 8 terminal connectors.
So far so good. Now I'm looking at the engine compartment diagrams. In addition to the alternator wiring for the Hemi that you posted, the diagram on the previous page shows four or five wiring configurations depending on the engine and whether an idle speed solenoid was used. None of these use a a connector like the Hemi wiring.
Is there, or was there a idle soldenoid on the throttle side of the carburrtor. Take a photo if it helps.
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