Ballast Resistor Voltage (Solved. The points failed)

[gary68plyfury]

Hey All,
I'm having a problem with starting my 68 Plymouth Fury 3 with a 383. It cranks over fine but no spark.
I keep going back to the ballast resistor(BR). I'm reading 12volts on both sides of the BR and I've tried 4 new BRs. I'm also reading 12v on the + side of the coil.
Three of the BRs are about .4 ohms and one BR is 1 ohm.
To test, I put two in series for a total of 1.5ohms but still have 12volts on both sides of the BRs. It's like the BRs aren't even installed.
I'm thinking/guessing I have a short somewhere.

Classic Industries has a BR that's $35 but it doesn't report it's Ohms.

I did have this same issue on Saturday. I tried troubleshooting for awhile, then let it sit for an hour and then it started without issue and I went driving around.

Any help would be great.
Thanks,
Gary

 

[MoPar~Man]

Are you reading 12 volts on the resistor (both ends of the resistor) while you're cranking the engine? That's normal I think, during cranking the resistor is bypassed to give the coil 12 volts instead of 8 to 10 with the resistor. Check the coil's resistance (across the 2 terminal posts). Disconnect one of the wires (on the coil post) to do that. It should be 1.5 to 1.8 ohms.

 

[Big_John]

I keep going back to the ballast resistor(BR). I'm reading 12volts on both sides of the BR and I've tried 4 new BRs. I'm also reading 12v on the + side of the coil.

That is because there is no load.

Basic Ohm's Law. With the BR, as the load (the coil) goes up the voltage will drop.

Let's say you have 12 volts and you want 5 volts. 12-5=7 volts

Let's say an ignition coil draws around 4 amps.

R=V/I or Resistance of your BR = voltage drop needed/ current draw of coil

R being the resistance needed in the BR.

So R= 7/4

R= 1.75 ohms.

Now, this is using 4 amps as an example. I'm not sure of your coil's draw and that is an approximate value.

 

[gary68plyfury]

Are you reading 12 volts on the resistor (both ends of the resistor) while you're cranking the engine? That's normal I think, during cranking the resistor is bypassed to give the coil 12 volts instead of 8 to 10 with the resistor. Check the coil's resistance (across the 2 terminal posts). Disconnect one of the wires (on the coil post) to do that. It should be 1.5 to 1.8 ohms.

Oh... 12v when the ignition was on. I didn't read the voltage while cranking. Didn't think too.

I did check the coils resistance and it was 1.2ohms

 

[Big_John]

I'm having a problem with starting my 68 Plymouth Fury 3 with a 383. It cranks over fine but no spark.

I made this a separate post because it has nothing to do with the ballast resistor.

When you twist the key to start, you bypass the ballast resistor. When you release the key to "run", then the ballast resistor is in the circuit.

Classic ballast resistor failure goes like this... Twist the key to start and the engine starts, release the key to run and the car stalls.

Too many guys will blame the ballast resistor for their problems and not understand how it works.

 

[gary68plyfury]

That is because there is no load.

Basic Ohm's Law. With the BR, as the load (the coil) goes up the voltage will drop.

Let's say you have 12 volts and you want 5 volts. 12-5=7 volts

Let's say an ignition coil draws around 4 amps.

R=V/I or Resistance of your BR = voltage drop needed/ current draw of coil

R being the resistance needed in the BR.

So R= 7/4

R= 1.75 ohms.

Now, this is using 4 amps as an example. I'm not sure of your coil's draw and that is an approximate value.

Thanks for pointing this out.

 

[MoPar~Man]

One side of the resistor is going to get 12 volts from the ignition switch when it's in the run position. The other side of the resistor is going to the + terminal of the coil. The other terminal on the coil is going to the distributor. If this is a points system, depending on where the distributor rotor is pointed the points might be open or closed. If they're closed, current will flow through the resistor and coil, you should get maybe 8 volts on the + terminal of the coil. If the points are open, then you'll get 12 volts on the coil. I think I've got all that right...

 

[gary68plyfury]

I made this a separate post because it has nothing to do with the ballast resistor.

When you twist the key to start, you bypass the ballast resistor. When you release the key to "run", then the ballast resistor is in the circuit.

Classic ballast resistor failure goes like this... Twist the key to start and the engine starts, release the key to run and the car stalls.

Too many guys will blame the ballast resistor for their problems and not understand how it works.

Ok...that means I don't totally know how the BR works. I'll start looking at things after the BR, such as the coil n points n condenser

 

[gary68plyfury]

One side of the resistor is going to get 12 volts from the ignition switch when it's in the run position. The other side of the resistor is going to the + terminal of the coil. The other terminal on the coil is going to the distributor. If this is a points system, depending on where the distributor rotor is pointed the points might be open or closed. If they're closed, current will flow through the resistor and coil, you should get maybe 8 volts on the + terminal of the coil. If the points are open, then you'll get 12 volts on the coil. I think I've got all that right...

OK. Thanks. I look at that tomorrow or this weekend. didn't think to read volts with points open and closed

 

[Mike McGuire]

Gary - - Sounds like your starter is turning but your ignition is not engaged. While working on this problem, consider checking your bulkhead connections, & fusible link. I had this problem once, but currently forget what the solution was. .. There's a temporary trick to bypass bulkhead by running a sufficient wire from the alternator to battery +. As Big_john put it, probably smart to temporarily rule out the ballast resistor. If those stuck neurons dislodge themselves, I'll reply back.

 

[gary68plyfury]

Gary - - Sounds like your starter is turning but your ignition is not engaged. While working on this problem, consider checking your bulkhead connections, & fusible link. I had this problem once, but currently forget what the solution was. .. There's a temporary trick to bypass bulkhead by running a sufficient wire from the alternator to battery +. As Big_john put it, probably smart to temporarily rule out the ballast resistor. If those stuck neurons dislodge themselves, I'll reply back.

Mike,
Thanks for helping. I beleive, if the bulkhead was the issue I'd have other problems such as headlights/blinkers/engine wouldn't turn off/heater fan wouldn't turn on. But I could be wrong.

I have a total of 5 BRs (ballast resistor), 4 being brand new. (Please don't ask why.) Four of the BRs are .4 ohm and one is 1 ohm.

I've read, in a few places, that the BR should be 1.5 ohm, but the one in the car, when it was running, was .4 ohm. So I'm thinking now, the .4 ohm burned out the points or maybe the coil or maybe the condenser. To test, I put the 1 ohm and .4 ohm BR in series, for a total of 1.5 Ohms, but still no spark.

Right now, I'm not getting a spark at the points OR when I put the coil wire close the engine and crank the engine.

I haven't had time to work/test on anything since before I created this post. Hopefully tonight or this weekend.

 

[Big_John]

Mike,
Thanks for helping. I beleive, if the bulkhead was the issue I'd have other problems such as headlights/blinkers/engine wouldn't turn off/heater fan wouldn't turn on. But I could be wrong.

I have a total of 5 BRs (ballast resistor), 4 being brand new. (Please don't ask why.) Four of the BRs are .4 ohm and one is 1 ohm.

I've read, in a few places, that the BR should be 1.5 ohm, but the one in the car, when it was running, was .4 ohm. So I'm thinking now, the .4 ohm burned out the points or maybe the coil or maybe the condenser. To test, I put the 1 ohm and .4 ohm BR in series, for a total of 1.5 Ohms, but still no spark.

Right now, I'm not getting a spark at the points OR when I put the coil wire close the engine and crank the engine.

I haven't had time to work/test on anything since before I created this post. Hopefully tonight or this weekend.

If you look in the FSM, it will show you exactly what the resistance of the ballast resistor should be. And that is .5 to .6 ohms at 70 to 80 degrees ambient. I attached a screen shot. Download a copy at MyMopar if you don't have one.

I seriously doubt if the .4 ohm BR burnt anything out. It's close enough. Have you actually looked at the points? They don't last forever.

If the points look good, run a jumper from the +battery to the +side of the coil and try to start it. That completely bypasses the key switch, bulkhead and all the wiring associated. Just don't leave it hooked up very long if the engine isn't running.

 

[gary68plyfury]

If you look in the FSM, it will show you exactly what the resistance of the ballast resistor should be. And that is .5 to .6 ohms at 70 to 80 degrees ambient. I attached a screen shot. Download a copy at MyMopar if you don't have one.

I seriously doubt if the .4 ohm BR burnt anything out. It's close enough. Have you actually looked at the points? They don't last forever.

If the points look good, run a jumper from the +battery to the +side of the coil and try to start it. That completely bypasses the key switch, bulkhead and all the wiring associated. Just don't leave it hooked up very long if the engine isn't running.


View attachment 626880

I have it downloaded. The points are about 6 months old, so they have a few hundred miles...says under 500 or700.
I'll jump the battery to the +coil and see what happens. Didn't know I could do that one but I'll try it very quickly.

Sounds like that will tell me if the issue is the coil or points or distributor.. OR something before the coil, which includes the BR or the wiring before the + side of the coil.

 

[Big_John]

I have it downloaded. The points are about 6 months old, so they have a few hundred miles...says under 500 or700.
I'll jump the battery to the +coil and see what happens. Didn't know I could do that one but I'll try it very quickly.

Sounds like that will tell me if the issue is the coil or points or distributor.. OR something before the coil, which includes the BR or the wiring before the + side of the coil.

Yes, that should point you in the right direction.

Remember, the ballast resistor isn't in the circuit until the car starts and you release the key to run.

Here's a simple diagram when you turn the key to start, the circuit called 14PK gives power to the coil. It bypasses the ballast resistor. When you release the key to run, the 16RE circuit that runs through the ballast resistor gives power to the coil.

 

[gary68plyfury]

Yes, that should point you in the right direction.

Remember, the ballast resistor isn't in the circuit until the car starts and you release the key to run.

Here's a simple diagram when you turn the key to start, the circuit called 14PK gives power to the coil. It bypasses the ballast resistor. When you release the key to run, the 16RE circuit that runs through the ballast resistor gives power to the coil.



View attachment 626889

Yes...just learned the ballast is bypassed while starting the car. Learned that after buying a few and trying everyone AND also learned if only the ballast is bad, the car would start and run until you release the key. Once you release the key the car would shutoff.

 

[Big_John]

Yes...just learned the ballast is bypassed while starting the car. Learned that after buying a few and trying everyone AND also learned if only the ballast is bad, the car would start and run until you release the key. Once you release the key the car would shutoff.

Sorry if I repeated myself or sounded condescending. I just wanted to be sure so you don't waste time chasing something that you didn't need to.

 

[gary68plyfury]

Sorry if I repeated myself or sounded condescending. I just wanted to be sure so you don't waste time chasing something that you didn't need to.

Didn't do either! No worries!!
And nothing wrong with repeating to me... I've watched a few videos on this issue and it didn't sink in until making this post and a fellow C Body member said it.

Thank you for all your help.
And Thank You to everyone else.

I'm dying to work on this issue and start on the carb issue...but that's for another time/post.

 

[gary68plyfury]

First, I want to give a everyone a BIG Thank You for taking your time to help me.

Found the issue last night, it was the points. I'll pick up a new set or two today. (Feel free to stop reading. the rest is just me babbling) I don't know what happened to them but the arm, that rides in the distributor cam/shaft, just stopped moving. I took it off and even in my hands it was hard to move that arm up/down or open/close. I had to force it to open then close. Funny story, don't laugh, I had to go get my moms reading glasses to see the points contacts better. Even then it was hard to see the points didn't actually close or touch. Putting a light behind it, I could see the light passing through. Put some WD on them, just playing around, and it got easier. They were brand new set that came with the car when I bought it in March. They were in the trunk.
But definitely learned more so those 6 hours or so weren't a total waste.

Thanks again to everyone to took your time to help me.

Gary

 

[Big_John]

First, I want to give a everyone a BIG Thank You for taking your time to help me.

Found the issue last night, it was the points. I'll pick up a new set or two today. (Feel free to stop reading. the rest is just me babbling) I don't know what happened to them but the arm, that rides in the distributor cam/shaft, just stopped moving. I took it off and even in my hands it was hard to move that arm up/down or open/close. I had to force it to open then close. Funny story, don't laugh, I had to go get my moms reading glasses to see the points contacts better. Even then it was hard to see the points didn't actually close or touch. Putting a light behind it, I could see the light passing through. Put some WD on them, just playing around, and it got easier. They were brand new set that came with the car when I bought it in March. They were in the trunk.
But definitely learned more so those 6 hours or so weren't a total waste.

Thanks again to everyone to took your time to help me.

Gary

Point failure like that wasn't real common until they started making them offshore. From what I see, the new condensers and points fail at an abysmal rate. Maybe some NOS parts would be good, but you are going pay a premium and lately I've been wondering about how many NOS parts might be counterfeit. After all, you really just need to print a box that looks right.

I'd suggest looking at the Pertronix ignition as a good upgrade. Yea... Guys are gonna say "but points are simple and won't fail", yet here's a good example of failure. I've used the Pertronix in one of my cars for a while now with no issues as have a lot of folks here.

 

[gary68plyfury]

Point failure like that wasn't real common until they started making them offshore. From what I see, the new condensers and points fail at an abysmal rate. Maybe some NOS parts would be good, but you are going pay a premium and lately I've been wondering about how many NOS parts might be counterfeit. After all, you really just need to print a box that looks right.

I'd suggest looking at the Pertronix ignition as a good upgrade. Yea... Guys are gonna say "but points are simple and won't fail", yet here's a good example of failure. I've used the Pertronix in one of my cars for a while now with no issues as have a lot of folks here.

Dead Dodge Garage Youtube channel likes the Pertronix ignition also. Any more crazy problems like this one I'll have to switch over. For now, I'm trying to keep the same way my Grandfathers did since they were both Chrysler guys when I was kids. Keeping it old school n original is great but that one little points issue was HOURS