1972 duster engine harness ECU electronic ignition

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72dustervs

72dustervs

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I bought a new engine harness from Yearone , but the old one is different , now I can figure out were the wires run , but my old harness has an extra plug , that I am just unsure were it plugs in at ? I can trace down to add to the new harness easy enough but am I missing something as to were it lands ? I did not remove this harness , it came with the car in a box

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the dash vin plate
codes as 340 but no door tag, as door was changed out at some point , many things were changed on this car in its life , I traced some of the wires back , and it ties in to oil pressure sending unit and temp sensor as well I thing it even ties to ignition ecu an perhaps ballast and voltage regulator , 6 wires are present on the plug,, Violet -should be temp but goes from Bulk head plug to this plug , Brown- ties to ballast , Grey- should be oil but goes from Bulk head plug to this plug ,, ,Green straight to voltage regulator,,Blue - ties to ballast ,, Black Yellow tracer - direct to ECM , but believe this is suppose to run to coil from ECM
 
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Found a wiring connector that may help.
Go to mymopar and look at the 1973 chassis service manual on page 8-167. See connector CE-37 The wire colors may be different but this is the connector in your photo.
It is located behind the valve cover on the passenger side. Not sure about 1972 but that connector is used on 73 thru 75 engines. Trace the wires back in the diagram.
Some of them go to the locations you described.
 
townsend will likely have specific info.
in the meantime, familiarize yourself with the service manual.
The edition from Mymopar shows the ECU ignition on a seperate diagram. Unless there is a service bulletin, it will be up to you to combine the two diagrams.
What you are looking at may be an engine connector. IIRC they show up in the '73 diagrams but for '72 mayb it was eitehr a mid year or just didn;t make the service manual diagram.

The bulkhead connnectors are keyed on the engine bay side. Each connector can only fit in one location.
The cavities are called out on the interior.
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Standard harness - points ignition
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J3 is ignition start
J3A is power to coil, whether in start or run.
Those two connect together at the 0.5 ohm resistor terminal.

J2 is power for the engine to run. it is hot with the key in run.
It must connect to the other J2 segments. such as J2A, J2B, J2E
According to the diagram, it is joined at a welded splice. However you may find some are connected at a terminal as shown in the points diagram.
J2E segment goes to the 5 ohm resistor, and then a short wire jumpers it to the 0.5 ohm resistor. 0.5 ohm resistor is for the coil. 5 ohm resistor was to control power to the ECU on the original ECUs.
J2E supplies power at system voltage to the ECU. That is needed on all ECUs.

J2B goes to the sensing terminal on the voltage regulator. That is critical for the regulator to work. With no connection the regulator will not regulate.
J2C goes to a field terminal on the alternator. That is critical for the rotor to get power.
R3 connects from the other field terminal to the regulator and acts as the return from the rotor. The regulator will control the field current by lettting R3 connect to ground as needed.
 
Functional Schematic. Engine connector not shown.
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Unless their is some additional info about the old harness,we can't say for sure that it is the original 72 engine harness. So with that being said, let's discuss the old harness you found in a box. There is a secondary harness that plugs into the connector in your photo. The various wires coming out of the secondary harness go to the coil, temperature sending unit, voltage regulator, etc.
So it's possible that the 72 doesn't use the secondary harness, at least from what you said it doesn't sound like the M and H one does.
Maybe someone with a 72 with a V-8 engine could check it out.
 
townsend said:
Unless their is some additional info about the old harness,we can't say for sure that it is the original 72 engine harness. So with that being said, let's discuss the old harness you found in a box. There is a secondary harness that plugs into the connector in your photo. The various wires coming out of the secondary harness go to the coil, temperature sending unit, voltage regulator, etc.
So it's possible that the 72 doesn't use the secondary harness, at least from what you said it doesn't sound like the M and H one does.
Maybe someone with a 72 with a V-8 engine could check it out.
Click to expand...
It may not be original harness as it wasn't melted like inside wiring , the inside dash wiring was toast because someone didn't know putting voltage on a dead short would lead to other issues it was a mess, wires for main areas were melted , was ready for a fire ,the wiring in box was ok but lots of green corrosion on ends, so I am replacing , just hadn't seen a junction like the plug on the car anywhere else , the new harness will be just fine ,, the car came with a 440 an different many things so not surprised its different wiring harness
 
ISN'T that which is pictured simply the BULKHEAD connector?
 
Agree its not an A-body bulkhead for those years.
Might be a bulkhead connector for a B or E body although I'd expect the bumpouts to be females
 
Mattax said:
Agree its not an A-body bulkhead for those years.
Might be a bulkhead connector for a B or E body although I'd expect the bumpouts to be females
Click to expand...
No its part of the engine wiring harness , the bulkhead connector is there on the engine harness , this plug is more like a distribution plug off the main engine wiring harness , its got certain wires that feed temp sending unit, oil sending unit , ballast and voltage regulator , and ecm . Its off an a-body car most like duster or dart , the bulk head plug is correct for the car , this plug ties in on the other end of engine harness , I am missing the other side for plug , I have never seen one like it , but it is factory, just unsure of exact car an engine , the rest of the harness is correct ,
 
Sometimes I should proof read my post before I post lol , as sometimes I am not being clear enough with the question , the original engine harness I have plugs in just fine at bulk head connector , it just has the plug in picture towards the other end of the engine harness , I was curious as what was missing , or if I really needed it, but now know I do not since the new Yearone harness does not have this plug , I could easily wire and solder in the way the old one is , but see no real need to since I do not have the other side of plug with the rest of wires . ,
I don't think it was the one that was original engine harness to the car , but was off a donor car close to same year , might be off a 6 banger or v8 who knows ? But its not a plug off engine harness that I have seen over the years on the few abodies I have owned and was curious as to what year/model car it came off of , the bulk head connector is an a-body and plugs in to the replacement dash harness bulk head properly that I bought for a 72 duster off another member here that had an original uncut harness , thanks for al the help and replies
 
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My '72 Dart doesn't have that connector. I replaced the firewall forward harnesses because I thought that they were somewhat brittle. My car was orginal not messed with harness. My opinion, put your new M&H harnesses in and forget about it. Though my car is a Dodge Dart and not a Plymouth Duster, they should be the same. Or, could your old harness have something to do with a California car?
 
CRUZE 418 said:
My '72 Dart doesn't have that connector. I replaced the firewall forward harnesses because I thought that they were somewhat brittle. My car was orginal not messed with harness. My opinion, put your new M&H harnesses in and forget about it. Though my car is a Dodge Dart and not a Plymouth Duster, they should be the same. Or, could your old harness have something to do with a California car?
Click to expand...
Not sure it's original to car, was in a box with purchase of car,,dash harness was fried due to people who shouldn't own wire strippers an no idea what they were doing , wires were melted through main part of harness an cut an spliced into other areas to try and get power to other lights an to other components , got pictures somewhere when removed, on my build page .
It is an abody harness, just off different car is my guess
 
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