Had a question about my wiring on the ballast resistor. Stock wiring '72 340 duster. The first pic is the resistor. Just wondering if the wiring is correct. In comparing it to the diagram, it seems backwards. Does it matter? This is the way it was when I bought it.
Ballast Resistor wiring
- Thread starter oldjunk
- Start date
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I'm assuming the resistors are non-directional...the reason there are 2 notches in the porcelain? So I'm guessing it doesn't matter. I guess thats why the brown/green connector has an elongated plastic guide on it...I guess so it's impossible to screw it up?
67Dart273
Well-Known Member
Yours is hooked up different than the diagram, but electrically correct.
There are two DIFFERENT resistors in the resistor ceramic.
Look at your resistor. The right end is looped together so this does not matter......feeds both resistors at that end. The top left is red/ green which is the wire feeding to the ecu. Look at the notches in the resistor. The resistor has the notch on the left side
Now compare to the drawing. Mentally rotate the resistor cw 90 and you have the lead to the box on the "upper" half of the resistor, same as yours, only difference is that it's on the opposite end of the resistor.
The prong on the connector is supposed to be designed so you cannot "get it wrong."
Now the truth is that there is probably very few "5 pin" boxes left which require a 4 pin resistor
Most newer boxes are "4 pin" whether they physically have 5 or 4. You must use an ohmeter to find out
A 5 pin box MUST use a 4 pin resistor.
A newer 4 pin box CAN use either a 2 or 4 pin resistor, it's just that the "other half" of the resistor is not used.
Notice this diagram is drawn different from the one you posted, is hooked up like you have yours
from this thead
http://www.forabodiesonly.com/mopar/showthread.php?t=260487
This diagram is a screenshot out of the '72 factory shop manual and it's wired like yours is
This shows the difference from MyMopar
There are two DIFFERENT resistors in the resistor ceramic.
Look at your resistor. The right end is looped together so this does not matter......feeds both resistors at that end. The top left is red/ green which is the wire feeding to the ecu. Look at the notches in the resistor. The resistor has the notch on the left side
Now compare to the drawing. Mentally rotate the resistor cw 90 and you have the lead to the box on the "upper" half of the resistor, same as yours, only difference is that it's on the opposite end of the resistor.
The prong on the connector is supposed to be designed so you cannot "get it wrong."
Now the truth is that there is probably very few "5 pin" boxes left which require a 4 pin resistor
Most newer boxes are "4 pin" whether they physically have 5 or 4. You must use an ohmeter to find out
A 5 pin box MUST use a 4 pin resistor.
A newer 4 pin box CAN use either a 2 or 4 pin resistor, it's just that the "other half" of the resistor is not used.
Notice this diagram is drawn different from the one you posted, is hooked up like you have yours
from this thead
http://www.forabodiesonly.com/mopar/showthread.php?t=260487
This diagram is a screenshot out of the '72 factory shop manual and it's wired like yours is
This shows the difference from MyMopar
.
BillGrissom
Well-Known Member
To verify correct, measure the resistance from the upstream side (with loop) to coil+. It should be < 2 ohm. If >= 5 ohm, you have the wrong resistor in the ignition path. Do this with the ignition off.
As said, unless you have the original factory ECU, it probably isn't even using the 5 ohm resistor. Measure resistance from your 5th pin (disconnected) to the ECU case. If infinity, it is a "dummy pin" like most after-market ECU's.
As said, unless you have the original factory ECU, it probably isn't even using the 5 ohm resistor. Measure resistance from your 5th pin (disconnected) to the ECU case. If infinity, it is a "dummy pin" like most after-market ECU's.
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