Difference in 4-pin and 5-pin ignition modules?

[halfafish]

I am chasing ignition issues and while contemplating solutions, I noticed some factory style ignition modules have four pins, others have five pins. Other than the obvious, what's the difference in the two? Both are listed on NAPA's site for my truck.

 

[halifaxhops]

The only difference in the circuit / ECM with the dual ballast is that the second ballast resistance feed power into the 5th pin on the ECU. That is no longer used, and unless you find a really old original vehicle or really old NOS, most any new ECU WILL be 4 pin.

You can use a 4 pin box in a 5 pin harness, but not the other way around

Incidently, the "single" (or other half) of the ballast is the same exact circuity/ wiring as the old points setup. In fact in an emergency, if the thing quits, you can stuff in a breaker point dist. hook the wire to the coil, unplug the ECU and go

In today's Chineseoficianicated products, hard to say, but ECUs usually don't fail that often

 

[pishta]

only used with the dual ballast resistor. can be adapted.

 

[67Dart273]

Don't get too excited about "5 pins." ALL new modules for sale will ELECTRICALLY be 4 pin whether they contain 4 or 5 pins.

 

[halfafish]

Thanks @pishta. Would you have a similar diagram for a 4-pin module by chance? All the stock ECM wiring was gone from the truck when I got it. If I can't get the HEI system sorted out I have the parts to go back to a standard Mopar ECM.

 

[67Dart273]

Thanks @pishta. Would you have a similar diagram for a 4-pin module by chance? All the stock ECM wiring was gone from the truck when I got it. If I can't get the HEI system sorted out I have the parts to go back to a standard Mopar ECM.

Only difference is that the left side of the resistor is not there with a 4 pin at far left of the diagram.

 

[pishta]

@halfafish fixed.

 

[halfafish]

@halfafish fixed.

Sweet! Thanks for the help.