D100 Wiring diagrams/pinout

[1973dusterkid]

Hey guys/gals I picked up a 1974 D100 a few weeks ago, looking for some wiring info. I am replacing all the wires on the engine harness and beefing up the charge wire, along with bypassing the amp gauge.
Do anyone have a pinout or diagram of the firewall bulkhead, I’m cleaning and Replacing all the terminals.

Also my ignition wiring to the coil has seen better days I have an Orange ECU with matching dual ballast resistor and coil, does anyone have a wiring diagram of the ignition circuit with a duel ballast and the staring bypass.

 

[67Dart273]

Sorry wish I new (if there is a source) to download them. I imagine there are old and reprints available here and there

 

[=Max Wedge=]

Catalog

 

[1973dusterkid]

Catalog

Thanks great info

 

[1973dusterkid]

I have another question or if someone could lead me to a answer, the ecu runs off the 5.0ohm side of the Ballast resistor does the coil and voltage regulator run or the 5.0 ohm side too?

 

[toolmanmike]

This goes to 71. it might help. MyMopar - Mopar Forums & Information - Mopar Wiring Diagrams

 

[67Dart273]

I have another question or if someone could lead me to a answer, the ecu runs off the 5.0ohm side of the Ballast resistor does the coil and voltage regulator run or the 5.0 ohm side too?

The great majority of ECUs no longer use that half of the dual resistor Think of the coil resistor. That part of the circuit is unchanged from the breaker points days. In fact, in an emergency, if the electronic system fails, you can plug a breaker points dist in, hook up the dist primary wire to the coil, and unplug the ECU and off you go

Each side of the dual ballast gets switched "ignition run" power (IGN1) The coil side goes to the coil + and the ECU side goes to the ECU. Again, most of these are now unused

A 4 pin ECU can use either a 2 or 4 pin ballast
A 5 pin ECU must have a 4 pin ballast
You can NOT tell a 4 from a 5 pin ECU as many still have 5 physical pins. Two ways to tell: On a working system, if you unplug the ECU side of the ballast and it still runs, it's a 4 pin ECU

If you do resistance checks on the ECU and the 5th pin is open it's a 4 pin.

 

[67Dart273]

The basic circuit. This omits the brown bypass circuit which goes to the bottom right terminal of the ballast. That provides system power during cranking. Notice the upside down "U" at the bottom of the ballast. That indexes the ballast as the two resistors are different. Once again, the right side, the coil side, is same as for points. If you have a 4 pin ECU you can unhook the left side and it will still run.

ECU !!!MUST!!! be grounded

 

[1973dusterkid]

The great majority of ECUs no longer use that half of the dual resistor Think of the coil resistor. That part of the circuit is unchanged from the breaker points days. In fact, in an emergency, if the electronic system fails, you can plug a breaker points dist in, hook up the dist primary wire to the coil, and unplug the ECU and off you go

Each side of the dual ballast gets switched "ignition run" power (IGN1) The coil side goes to the coil + and the ECU side goes to the ECU. Again, most of these are now unused

A 4 pin ECU can use either a 2 or 4 pin ballast
A 5 pin ECU must have a 4 pin ballast
You can NOT tell a 4 from a 5 pin ECU as many still have 5 physical pins. Two ways to tell: On a working system, if you unplug the ECU side of the ballast and it still runs, it's a 4 pin ECU

If you do resistance checks on the ECU and the 5th pin is open it's a 4 pin.

It’s a 4 pins ecu and 4 pin ballast resistor
So the + coil wire and the ecu ign wire need to run off the which side of the Ballast resistor the low ohm side and have nothing running off the High ohm side

 

[1973dusterkid]

The basic circuit. This omits the brown bypass circuit which goes to the bottom right terminal of the ballast. That provides system power during cranking. Notice the upside down "U" at the bottom of the ballast. That indexes the ballast as the two resistors are different. Once again, the right side, the coil side, is same as for points. If you have a 4 pin ECU you can unhook the left side and it will still run.

ECU !!!MUST!!! be grounded

View attachment 1715618519

Thank you very much this is exactly what I needed

 

[1973dusterkid]

Ok so I have it wires just how it shows in the below picture and with the ignition on the Ballast resistor gets very hot and smokes a lot engine will also not fire any ideas

 

[67Dart273]

OK first that diagram is wrongly labled. The YELLOW wire does not go to the start relay

It is correct that with key on (and you should not leave the key on) the ballast will get hot

Check if you have power to the coil+ when cranking on the starter. If not you have disconnected the brown ballast bypass circuit. This comes from the key off IGN2, usually brown, goes into the engine bay, and connects to the coil + side of the ballast. It should have been present with your original wiring, you likely cut it

UNLESS...............I don't know when / if Dodge went to the newer style "Jeep" starter relay. Look at your starter relay........how many terminals does it have? If 4, then the above is correct. If 5, then the 5th terminal goes to the coil+ Like below.................has 5..........

 

[1973dusterkid]

OK first that diagram is wrongly labled. The YELLOW wire does not go to the start relay

It is correct that with key on (and you should not leave the key on) the ballast will get hot

Check if you have power to the coil+ when cranking on the starter. If not you have disconnected the brown ballast bypass circuit. This comes from the key off IGN2, usually brown, goes into the engine bay, and connects to the coil + side of the ballast. It should have been present with your original wiring, you likely cut it

UNLESS...............I don't know when / if Dodge went to the newer style "Jeep" starter relay. Look at your starter relay........how many terminals does it have? If 4, then the above is correct. If 5, then the 5th terminal goes to the coil+ Like below.................has 5..........

View attachment 1715619449

It’s a 3 pin starter relay I removed the bypass wire from it and ran it to a start 12v wire coming from the buck head connecter and it runs good now I got 10.05 bolts at the coil with engine running

 

[67Dart273]

It’s a 3 pin starter relay I removed the bypass wire from it and ran it to a start 12v wire coming from the buck head connecter and it runs good now I got 10.05 bolts at the coil with engine running

Ok you need to be more specific about what you are talking about. Your ran what "start 12v" and you ran this to where?

If you ran your start wire that goes from the bulkhead over to the start relay--and branched that off to the coil, you have created a problem, as the starter relay will drain off coil power through the ballast

The start wire to the start relay (usually yellow) and the coil ballast bypass circuit (usually brown) do the same thing at the same time, but they are separate contacts on the ignition switch to prevent backfeed

 

[1973dusterkid]

Ok you need to be more specific about what you are talking about. Your ran what "start 12v" and you ran this to where?

If you ran your start wire that goes from the bulkhead over to the start relay--and branched that off to the coil, you have created a problem, as the starter relay will drain off coil power through the ballast

The start wire to the start relay (usually yellow) and the coil ballast bypass circuit (usually brown) do the same thing at the same time, but they are separate contacts on the ignition switch to prevent backfeed

I left a wire out from the bulkhead the brown wire you said not sure why I did mush have not worried about thinking it need to go to the starter relay. Running good now.