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Discussion Starter · #1 ·
Hello All!

Got a problem here with my 71' W100. Made enough room in the garage for the truck to inhabit for the winter. Went back outside, started the truck ( had fired off on the first try after sitting two weeks ), got out of the cab and walked over to the garage door to lift it open.  Before I could turn around, the truck shut off. The truck shut off so, as to be compared to the flick of a light switch- instantly!! Based on how the Dodge Swept Side has been running lately, I have to ask if the failure is because of a ballast resistor? But now I'm  more confused because when I hit the key again, Its my understanding that the ballast resistor is by-passed during starter operation. So, how come I don't have any spark? I can test the ignition coil if I know what a good reading should be. I believe I have a new (er) ignition key switch. I'm going to go back out after a while and see if she starts after cooling down a bit.


Has to be something simple. I'd be greatly thankful for any ideas I could search out and try.
 

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The 70's electronic ignition, used a dual ballast. One side was for the normal coil side, like most other points, and ignition systems. The second side provided lower voltage for the electronic ignitions inner workings.

If that second side died (rare, but it does happen), then you will not get any spark at all.

If the main side died, it should act like you think, starting, and dying when you let off the key.

The 80's trucks, did away with the second side of the ballast, and did the voltage reduction inside the electronic ignition box. Those boxes (commonly called 4 pin ECUs)used the same plug as the 70's trucks, just missing one of the pins, and will even work in a 70's truck.

So, you can use the newer 4 pin ECU in any 4 or 5 pin system.

You can only use a 5 pin, in a system with the second side of the ballast.

Tossing all that out there, as many people with the 70's trucks, panic when the ECU they get from the parts store only has 4 pins, and sometimes pay extra for a 5 pin ECU (often the 5th pin is fake).

Now, the 70's trucks bypass the ballast like you know, when the key is in the start position. What many do not know, is there is no power to the normal side of the ballast, in the start pos. You could try jumping power to either end of the ballast (make sure its the one that goes to the coil ), to test the key wiring. Or even jump right to the positive side of the coil.

Sorry, I do not kn ow the specs of the coil right off.

So no spark, during the start cycle, generally  leads to the coil, or ECU, or wiring, being bad.

Hope something I posted helps you.
 

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Wouldn't a 71 still have points?

Not that it would matter concerning a ballast failure.

Bucky
 

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Discussion Starter · #4 ·
Oh boy.

I'm sorry that I did not mention that I most likely have an early 80's 318 engine in my 71' W100 Swept Side. I keep going back to my new Dodge Trucks Service Manual 1969 To 1971, and come up confused and empty handed. So, I basically have a good manual that only helps me a little. With whats known about my truck so far, and with the help from the group here at RamchargerCentral.com, is that I have a 71' D100 that was originally a two wheel job, '75-'79 front and rear axles, and I was told an '84 Ram Charger engine and Loadflite A727 a/t . UGG!! So nothing lines up, nothing is square, wires all have black tape then go into another color wire out the other side of the black tape, and a full slew of other things to do.


Anyhow, on the positive note, I went through all 30 topics that came up when I used the search engine here at the forum. And that is super helpful. So, now that the truck is inside, I can do a few checks that I'm finding out about, and get back on the propeller measurement thread I have started.  I'll report back soon! Thanks, John
 

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Discussion Starter · #5 ·
This video of me starting up the W100 this summer. It popped off all three times I hit the key. Those old Mopar starters crack me up, with their disengagement baby rattle noise they make! Got'er on the third pop as I had to prime fuel from a lawn mower can in the bed.

 

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ok what I'd do is buy a factory service manual either e bay or dodgeboys member here may have one , it will have the wiring diagrams . The year of the engine really makes little difference in your case , because , the distributor from any year will fit , so which "accessory's  " did they use is the key , from seeing a "ford" or generic style starter solenoid pictured , you need to do some wiring checks anyway , , bolting the ecm onto the fenderwell is a bad idea , unless a ground has been run from motor to base of ecm , the fenderwell often rusts and isn't well grounded .... it was on the firewall , which had a dedicated ground strap ... yes a dodge factory book ...  ;)  that solenoid CAN work , but must be wired to operate with a resistor , or the coil replaced with an internal resistor unit ...
 

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Discussion Starter · #7 ·
dodge82273 said:
ok what I'd do is buy a factory service manual either e bay or dodgeboys member here may have one , it will have the wiring diagrams . The year of the engine really makes little difference in your case , because , the distributor from any year will fit , so which "accessory's " did they use is the key , from seeing a "ford" or generic style starter solenoid pictured , you need to do some wiring checks anyway , , bolting the ecm onto the fenderwell is a bad idea , unless a ground has been run from motor to base of ecm , the fenderwell often rusts and isn't well grounded .... it was on the firewall , which had a dedicated ground strap ... yes a dodge factory book ... ;) that solenoid CAN work , but must be wired to operate with a resistor , or the coil replaced with an internal resistor unit ...
I'll try an extra ground wire from the base of the E.C.M to the engine, as suggested. I'll also make sure the negative battery terminal has a ground to both the engine and radiator support. I never had a chance to notice if my ignition coil was hot to the toutch or not. I do know all was well with the E.C.M location as the truck would start and run as shown in my video I made this summer,.... but hey I'm all eyes and ears!

Yea, these wire-tape connections must be took apart, re-wired and taped. The starter solinoid was part of the starting circut as I recieved the truck. I do have a new internal resistor ignition coil I could try, but I need to be sure I can figure out the problem as well. I did run across a Napa part # ECHICR23 ballast resistor that in shape does not look like what I have on my truck now,. If I had my helper with me at the moment, I could try to probe for 12 volts at the ballast resistor with the key in the "start" position.

There are a few diffrent distributor untis Chrysler used listed in the manual I have, and I'm undetermined as of yet, which one I have and to identify the dual / single "pick-up" to test for an ohms reading. But even that seems like a chase considering how instantly the truck just shut down. Tach-Dwell unit to "calibrate" ? I'd have to study up on that science to determine a check there.

Here is the manual I have. Little on the pricy side, but an offical reprint. My camera was a little cold from being outside when I used it.

SuperBurban, Thank you for your help!

712edf, I appreciate your help too! Last time I checked the rotor and contact points of the distributor cap, I did not notice any points under there. Something tells me I'm going to want to check it all again, however!
 

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Discussion Starter · #8 ·
I definitely have the dual ballast resistor, which in more common with the 5 pin ignition module. Looking at these dual ballast resistors from Summit Racing. Part # SMP-PU12 . They are O.E.M replacements, and I might just as well order three. Tomorrow is looking like more time to begin the quest of figuring out the instant shut-off of my truck.
 

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you should have 12 v at coil in crank , some what less when in ON / Run spot . the ecm controlls the ground to the coil , same as old points did . a dizzy with 2 connector plugs (  A 2 wire AND a 3 wire )is a dual pick up / or start/run pick up,  a dizzy with one 2 wire plug is a single pick up .... super is correct in that a dual will work with a 4 wire ecm , and the 5 wire ones are often fake , for more money . rust changes the chance of a good ground on the fenderwell is all ....
 

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Having the ECM means you have the electronic ignition, not points. The original ignition system that came in the truck new, had points. I suspect the ignition was upgraded to electronic when the engine was swapped.

Virtually every Dodge I have owned required MAJOR wiring work upon purchase. Seems previous owners ALWAYS made weird & questionable modifications.

Bucky
 

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Chrysler offered electronic ignition as an option in '72 and it was standard across the board in '73. Like the advent of fuel injection in '88, it cut warranty claims by a massive amount. I'm not sure about '73 but warranty claims for '88 dropped 80% with the advent of fuel injection. Chrysler offered F..I. in the early 80's but it wasn't a very good system.

If you think the ballast resistor is bad, use a jumper wire across it. If it starts, you have a bad ballast resistor. Back in the 70's, myself and everyone I knew who drove Mopar's kept an extra ballast resistor wrapped in a towel in their tool boxx.
 

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me? , I just kept the made up jumper wire ,( 2 male spades onna 3 inch wire) and an ecm ....... replaced the finger nail file and screwdriver .... LOL
 

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Discussion Starter · #13 ·
I can't say enough for the help, thank you! Just a quick post, got much to do today, lol! I do have a 5 pin ecm, and there does happen to be a jumper wire going from top to bottom off the dual ballast resistor. The ballast resistor checks out with 7.1 ohms across the top, while across the bottom of the ballast resistor reads 2.5 ohms. I'm in the process of removing all the old electric tape from the ecm to the ballast resistor, checking the twisted connections, and re-taping. Its quite a wire for sure! Got a few things to post for pictures along the way.
 

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Discussion Starter · #14 ·
I went to Napa and picked up a new dual resistor. I tested the new part and got a reading of 5.7 - 5.8 ohms resistance across one set of resistor terminals, and 2.0 ohms resistance across the other resistor set of terminals. The new resistor clearly has lower resistance numbers than my current, old resistor. I'm going to finish making sure all the wire splices are of good connection, and trace the leads going from the e.c.m to the distributor as well. I'm also going to rout a ground wire to the base of the e.c.m as suggested.


I plan a little experiment to test in ohms two different types of ignition coils. One, being the external resistor coil that's now on my truck, and the other coil being an internal resistor that I have as a back up for one of my garden tractors. For the ignition coil that's now on my truck, I'm looking for a ohm reading of 0.75 - 0.81 resistance between the positive and negative coil terminals, called the primary ignition test.  I'll also want to test the secondary ignition, looking for a 10,000 - 11,000 ohm resistance from the center high tension coil terminal to any given primary coil terminal. I don't know what test readings to expect from the internal resistor ignition coil.


Below are a few pictures of the current dual resistor with the many wire leads to it. I don't know what to say or make of the configuration. Also, I'm considering a new e.c.m just for the simple fact of having new parts on the truck, not to simply just guess at the problem I have with the sudden engine shut down. Napa is asking $53.99 for a new e.c.m , which as of now seems like the part price is a little steep. Summit Racing has it for $29.99 .  Have to note, that you should always open your parts at the parts counter in front of the sales clerk. I did and noted a chunk missing from the ceramic ballast resistor. The clerk said it would be fine, so I went with that as there was not another part in stock. 

For the record, the new Napa dual ballast resistor part # is ICR24 / V18156 .
 

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According to my 77 manual, the coil side of the ballast should read .5 to .6 ohms, The other side, should be 4.75 to 5.75 ohms.

since your setup does noy use the original plugs for the ballast, you need to pay extra attention that you are connecting the coil to the .5 side, and the other side goes to the ECM. The wrong way could fry the ECM.

Like I said before about the difference between the 70's, and 80's ECM. Save yourself some heartache, and get one from an 80's 360. That way you cannot hook that second side of the ballast up wrong, since it is not possible to wire it to the ECM.

Several aftermarket 5 pin ECM's that I tested, the extra pin, is fake, so why pay more money for the same thing, plus a fake pin.
 

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Discussion Starter · #16 ·
SuperBurban said:
According to my 77 manual, the coil side of the ballast should read .5 to .6 ohms, The other side, should be 4.75 to 5.75 ohms.

since your setup does noy use the original plugs for the ballast, you need to pay extra attention that you are connecting the coil to the .5 side, and the other side goes to the ECM. The wrong way could fry the ECM.

Like I said before about the difference between the 70's, and 80's ECM. Save yourself some heartache, and get one from an 80's 360. That way you cannot hook that second side of the ballast up wrong, since it is not possible to wire it to the ECM.

Several aftermarket 5 pin ECM's that I tested, the extra pin, is fake, so why pay more money for the same thing, plus a fake pin.
"Coil side of the ballast" Let me think about that for a while. What exactly am I checking? I'd like to check for the .5 ohm at that location.

I take careful, and close pictures of the parts and components I'm about to work with, so there is no "hooking up" any wires differently. The truck started and ran flawlessly, I posted my video to make note of it. I cant deny what has proven to start the truck. I don't like the way it's wired as there are so many splices, old wires, and just a total hack. However, plans for removing every, single wire from the truck and replacing with new is not in the cards right now. I just need to unlock this mystery, and gain a great educational experience.

May I ask you how you would go about testing the e.c.m ? Could it be possiable that the e.c.m failed? With all the extra work at the shop, road trips, and research, I have not much time during the work week to get out to my W100.

I appreciate your knowledge and patience with a noob like me. Thank you!
 

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A ways back when my truck had the stock ignition set up with all factory parts... I had an issue with it suddenly just shutting off for no reason.
It turned out to be the pick up coil inside the distributor.
That pick up coil sits there inside like the points used to.
It is mounted on an adjustable plate to set the gap between it and and the 8 point reluctor that's mounted on the shaft.
It will randomly just quit.
Then start working again.
Just something else to check on.  ;D
I'm still running a pretty much stock (recurved) distributor.
 

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Uncle John said:
"Coil side of the ballast" Let me think about that for a while. What exactly am I checking? I'd like to check for the .5 ohm at that location.

I take careful, and close pictures of the parts and components I'm about to work with, so there is no "hooking up" any wires differently. The truck started and ran flawlessly, I posted my video to make note of it. I cant deny what has proven to start the truck. I don't like the way it's wired as there are so many splices, old wires, and just a total hack. However, plans for removing every, single wire from the truck and replacing with new is not in the cards right now. I just need to unlock this mystery, and gain a great educational experience.

May I ask you how you would go about testing the e.c.m ? Could it be possiable that the e.c.m failed? With all the extra work at the shop, road trips, and research, I have not much time during the work week to get out to my W100.

I appreciate your knowledge and patience with a noob like me. Thank you!
The dual ballast, is two big resistors inside. The main side/coil side/ compensating resistor, what ever you want to call it, is the side that has a wire going to the coil. The side that you measured as .5 ohms.

Just saying with your setup, take the extra step to make sure the right wire is going to the right side.
 

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Discussion Starter · #19 ·
SuperBurban, Thank you for posting the diagram. I'll be sure to refer to it. Going to carefully go through, and trace these wires. Not a problem for me!
 

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Discussion Starter · #20 ·
Not much to report. Had just a little time to monkey with the problem. I put the new dual resistor inline, and still no spark. I have power to the coil with the key in the run position, along with power to all 4 points of the ballast resistor. I did not measure voltage at the coil with the key in the run position. I got to go get some new wire and rewire much of the primary circuit. Then I'm going to try for a new e.c.m, and voltage regulator. I wonder if that thing-a-moe-Bob in the distributor is faulty. Much to do, much to learn about!


I'll need to refer back to the diagram!
 
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