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Smoking Ballast Resistor

Mopar Muscle
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Smoking Ballast Resistor

1bad67coronet 1bad67coronet
New User | Posts: 1 | Joined: 12/12
Posted: 12/26/12
03:21 PM

I have a 67 Dodge Coronet with a 73 model 360 engine.  After straightening out the wiring harness, I've noticed I have power on both sides of the resistor with switch on or off  Confused - any ideas???  

pepsi1 pepsi1
User | Posts: 150 | Joined: 10/11
Posted: 12/26/12
09:28 PM


Are you running a point type ignition?

If so then.

You should have power on both sides of the resistor. BUT!

For EXAMPLE only: If your input voltage is 12.4 vdc. The ballast resitor drops the voltage to a safe range of whatever for example again 10.5 vdc. So it doesn't kill the points prematurely. I hope that helps.

If you have an aftermarket ignition you probably don't need the ballast resistor.

Just a little FYI: The voltage drop across the ballast resistor depends on the manufactured resistence in it.... Grin  Cool


waynep71222 waynep71222
User | Posts: 246 | Joined: 04/12
Posted: 12/27/12
07:41 AM

since you did not mention which ignition system you have..
if you have a 2 terminal ballast resistor..   the diagram below is not correct for you...
since you have a 67... well thats another depending on what you have..

i will post this 73 electronic ignition diagram that i colorized... it may or may not help you.  but if you have power at the resistor when you have the key on or off.. you probably have a short or a burned ignition switch..   or.. perhaps.. and i will have to look it up the resistor bypass circuit might be shorted to power... more to come while i examine the 67 wiring diagram.

Mopar Electronic Ignition Diagram  

waynep71222 waynep71222
User | Posts: 246 | Joined: 04/12
Posted: 12/27/12
08:41 AM

the 67 coronet wiring diagram is very similar. if you are still using the big box with wires on the end voltage regulator...

the dark blue wire comes from the ignition switch.. feeds the gauge cluster and the brake warning light.. but also the ignition side of the voltage regulator and the single wire end of the ballast resistor..  this supplies current to the ballast resistor.. so it can be reduced to the coil + for normal operation

ahh... but the other end of the ballast resistor has 2 wires.. one to the positive side of the coil and a brown wire.. that also leads to the ignition switch...  that brown has gets power from the ignition switch only when the ignition key is turned to the Cranking position..  this sends full battery voltage to the ignition coil.. so the spark is hotter for an easy start..   but.. wait..

during normal operation when the power is coming through the dark blue wire..  the brown wire has the same reduced voltage the coil positive has..  its just there... this is totally normal..

so... let us know what you have for an ignition system.. and the type of voltage regulator .. the one with terminals on the ends. or with terminals on the face...

you will probably want to examine the ignition switch...

what's amazing.. my local az actually stocks the ignition switch for under 20 bucks..

the blue wire goes on IGN1
the brown wire goes on IGN2.  

manny-43 manny-43
New User | Posts: 1 | Joined: 12/12
Posted: 12/30/12
11:16 PM

Hi, I'm having a related ignition problem. I have a 360 engine with electronic ignition (MSD Blaster). Every thing looks correct including the resistor. It is hard to start and when it does, it runs for a few seconds to minutes and then dies. I was told to install a resistor to reduce the voltage but it has one  Confused It starts after several minutes and then dies again. Any ideas?
Thanks, 1940 Plymouth  

waynep71222 waynep71222
User | Posts: 246 | Joined: 04/12
Posted: 12/31/12
01:28 AM

manny ... got a timing light..   hook it over the coil wire..   tape or rubber band the trigger on... lay it on the windshield so you can see the flashing light...   does the light stop flashing before the engine stops?? or does it flash slower and slower until it stops at the same time the engine comes to a complete stop...

a little more info on your system manny...  

i am taking its just the MSD blaster coil... that blaster coil could be pulling more amperage than the ignition module could supply on the ground side... got a part number from the coil so i can look up the resistance to calculate the amp draw..

if you have just the blaster coil and a mopar electronic ignition .. can you monitor the voltage on the positive side of the coil  with the key on.. and then with the engine running.. even though it dies soon..  with the other lead of the meter hooked to ground...    then do it again..   with the other side of the volt meter hooked to the positive battery post..

the first test coil positive to ground gives us the voltage at the coil... and if it fails..

the second test.. positive coil to positive battery post gives us the voltage drop. so we can see if the supply voltage is failing..  like it could have a bad ignition switch contact.. or a bad connection someplace in the circuit..

do you have proper braided ground strap between the back of the head and the mounting bolts on the module..  so the spark has the ability to make a complete circuit..

did i post the voltage drop test above...  

waynep71222 waynep71222
User | Posts: 246 | Joined: 04/12
Posted: 12/31/12
01:34 AM

VOLTAGE Drop Testing