Ignition Module Question

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73318duster

73318duster

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Long story short, I bought this 73 Duster w/ a 318. After sitting for 2+ months due to complete roof replacement ect, I tried to start it up. The wife's nephew who claims to have worked at a shop before put the battery on backwards. Some smoke came out of two separate wires so i took the cables off the battery, never turned the ignition key. I decided to change the ballast resister, voltage regulator, and the ignition control module. I noticed this sticky black stuff on around it and after taking it apart I discovered that the black stuff (not sure what the proper term for it is) had melted off the module. After replacing the mentioned parts the car started and idled fine. Is there a reason as to why that melted and is there something that I need to check to make sure this doesnt happen again?:newb:
 

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Dont have much of a response to your question but ive always wanted to see the insides of one.
 
probably just the potting material that keeps things dry. So the battery was in backwards until YOU took the terminals off? trying to figure out what would cook...
 
it was probably on backwards for about 20 secs or so. Looks like the module was already like that when I purchased the vehicle.
 
some melt out over time, not sure if its due to bad potting material used or bad ground causing heat
 
Hopefully it wont happen to the new one. I picked up a BWD - Ignition Module/Control Unit/Ignitor Part Number: CBE14P from O'Reillys Auto Parts as a replacement. I noticed it had four pins instead of five. The guy at the counter said that the part was ok to use.
 
Yup,it's fine.Forget what the extra pin is for,possibly tach?
 
Not sure. Im new to MOPAR. That does bring up a good question though, if this is for a tach, which I currently dont have, would it cause any issues if I install one in the future? Is a tach difficult to install?
 
The 5th pin isn't for the tach. Tach goes to neg terminal on dizzy. I forget what 5th pin is but i think it was for 4 pin ballast resistors. I haven't seen a 5 pin module in years and never saw one from a aftermarket source.
 
No and no. I've run a 5 pin module plently of times when it calls for only 4. The aftermarket tach's are very easy to install,usually only 3-4 wires to hook up.
 
The biggest things that would be damaged / reversed polarity:

The circuit path from the alternator output, through the bulkhead, the ammeter wiring, back out the bulkhead and through the fuse link to the battery

The alternator itself. The DIODES are what are pulling the brunt of this, they are all forward biased, and conducting like 'ell. So you MAY have damaged the alternator

SOME stereo equipment. Some stereo gear hooks the output transistor amplifier direct to battery hot, so it may or may not be damaged. I doubt a stock radio would be damage --it should be switched both by the radio switch and the IGN switch.

There may or may not be some other minor things, like a "solid state" clock.

By NOT turning on the ignition, you saved yourself a world of hurt

If you turned on no lights, nor turned on the key, then anything that is switched is OK

I think the potting material is just coincidence, caused by age, and has finally broken down and deteriorated.

IF YOU have not tossed the old one, I'd pay shipping for the old ECU, I'd like to see if I can finish unpotting it and look over the circuit.
 
They did have one with a 5th pin. I believe the brand was ACDelco but it was not in stock they had to order it.
 
Never turned on the lights until yesterday after I got the engine to turn on. One headlight was burned but it might have come this way, the car does have an aftermarket stereo (Dual brand)but not speakers. The stereo was off so I am not sure if it has been wired yet or not. Hopefully the alternator is not damaged otherwise I will have to replace that down the road.

I did not dump it out, threw it in a box with some of the other parts I replaced. If the wife hasnt thrown it out when I get home I will mail it out to you. Just PM me your shipping details.
 
Thanks for posting the photo. It looks like a very simple circuit. Once 67Dart273 gets it, I bet he will post a circuit schematic, since he is a detailed guy. Us FABO guys might go further and pick a better transistor to upgrade the design, which is outdated. At my last job, I designed a circuit to pulse an EM coil using a Motorola FBGT. I tested it by switching a Mopar ignition coil to jump a 1" gap. A bright spark. Left it going all weekend with no failure.

mcnoople is correct. The 5th pin was for dual ballast resistors, which were probably on the earliest electronic ignition cars. The second ballast was to protect the ignition module itself. They later re-designed it so the module could handle full 12 V, so didn't need the extra ballast or pin. Just because you have a 5th pin doesn't mean it is used. Many were made that way, with the 5th pin unconnected internally.

Anyone installing electronic ignition in a points car might do better by using a GM HEI module. Many FABO posts on that.
 
Be careful with chosing a ballast when you change it. They are sized based on the coil ohm rating. If you have a stock coil and electronic ignition, you want the combined ohm rating of the coil and the ballast to exceed 1.5 ohms so the coil and the ECU will live.
 
mcnoople said:
The 5th pin isn't for the tach. Tach goes to neg terminal on dizzy. I forget what 5th pin is but i think it was for 4 pin ballast resistors. I haven't seen a 5 pin module in years and never saw one from a aftermarket source.
Click to expand...


5 pin modules draw power from the 5 ohm side on a 4 wire resistor and it goes to pin 3 of the ECU, can run any car with or without them
 

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My 84 truck is wired for a 4 pin module and I tried to use a 5 pin I have around. would not work. the same 5 pin module would work on my duster which was wire for the 5 pin. my duster will also work with a 4 pin. So what I have found is that a 4 pin will work with most systems but a 5 pin will only work in a system wire for 5 pin.
 
mod5v said:
My 84 truck is wired for a 4 pin module and I tried to use a 5 pin I have around. would not work. the same 5 pin module would work on my duster which was wire for the 5 pin. my duster will also work with a 4 pin. So what I have found is that a 4 pin will work with most systems but a 5 pin will only work in a system wire for 5 pin.
Click to expand...

Exactly. A 5 pin module MUST have a 4 terminal ballast

A 4 pin module MAY use EITHER 2 or 4 terminal ballast

You can NOT tell a 4 or 5 pin module apart, because some 4 pin modules do have a dummy 5th pin. Only way to tell is to probe around with an ohmeter and look for continuity from the 5th pin to others.
 
mod5v said:
My 84 truck is wired for a 4 pin module and I tried to use a 5 pin I have around. would not work. the same 5 pin module would work on my duster which was wire for the 5 pin. my duster will also work with a 4 pin. So what I have found is that a 4 pin will work with most systems but a 5 pin will only work in a system wire for 5 pin.
Click to expand...

yupp 5 pin module's aren't that great because there not interchangable. anyone you buy new will be a 4 pin, and you can use a single ballast as a replacement too if you have a 4 pin module
 
Yeah, when you buy a ballast, make sure you get one that is at least 1 ohm. That will save your coil and keep it from burning up. The parts stores have books that they can look up a ballast for you. My electronic ignition conversion came with a 1.4 ohm ballast.
 
so the lower the ohm rating of the ballast the more juice it sends out to the coil? or is it the opposite the higher the number of ohm rating the more juice it sends to the coil? i would think the lower the ohm number the morre juice goes to the coil but not 100 percent so thats why i am asking.
 
zero ohms would be no resistance to current, so the lower the figure, the more current flows.
 
So you should run a ballast with a little lower ohm rating to get more juice to the coil correct? as long as its not enough juice to fry it anyways.
 
pjc360 said:
So you should run a ballast with a little lower ohm rating to get more juice to the coil correct? as long as its not enough juice to fry it anyways.
Click to expand...

most chrysler round coils are required to have between 1-1.5 ohm resistance, if you want more fire go with an accel coil or a flamethower coil, what ever you do don't remove the ballast resistor on a stock coil or it could die anytime in the middle of no where
 
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