New ECU wiring question

[DustyEd]

I'm "duplicating" a points system conversion to electronic ignition in my '70 Duster 340.

Q.#1.....Which side of my 2 post ballast resistor does the light blue*yellow tracer wire (from a 4 pin ECU) go? I just installed a new points system engine harness (center bulkhead connector). This harness has a light blue* white tracer wire for one side of the ballast resistor and a brown wire and dark blue wire (connected together) for the other side. I know the light blue*yellow tracer wire is suppose to be spliced into the "feed/run" wire(s), but with other harnesses presently out I cannot turn the key to determine which side is the feed/run.

Q.#2.....The new engine harness has a dark blue wire (same wire mentioned above connected with the brown wire at the ballast resistor) for the(+) coil post and the ECU has a black*yellow tracer wire for the (-) coil post. Is this all the wires I need at the coil?

These might be basic questions, but I want to be sure in order not to fry the system when I start it up. Thanks for your help.

 

[Demonic]

Dual ballast version...

 

[67Dart273]

Don't go by wire colors, go by the wire positions in the harness connector. Not all harnesses use same wire colors

NOTE NOTE NOTE. There is a MISTAKE in the colored diagram. DO NOT run the yellow start wire from the starter relay as shown. The wiring you need should already be in place as per breaker points. The yellow they are showing is instead the brown bypass IGN2 wire.

THIS IS IMPORTANT because the yellow start used instead of the brown IGN2 will cause backfeed problems and drop down the running coil voltage. On a "stick" car where the starter relay is grounded, this may also cause the relay to try to stay engaged

(The yellow start and the brown bypass IGN2 both "act" the same way....that is they are both hot in "start." But they are two isolated contacts in the ign switch, and therefore isolated from each other)

What may or may not help is that the resistor/ coil wiring is EXACTLY the same between breaker points and electronic

Coil NEG goes to the ECU instead of points. The ECU box is powered by a tap off at the "key" end of the ballast. Other than that THERE ARE NO CHANGES

Make certain the ECU (and your VR) are both grounded

 

[DustyEd]

Diagrams are nice, but not definitely answering my questions.

One, my yellow wire from starter relay is not going to the ballast resistor (see top diagram). Mine goes directly to and through the bulkhead then to the steering column.

Two, the "blue main ignition feed"(top diagram) is the topic of my question #1 above. Is this the "blue" of the blue/brown wires? Or, is this the "blue" of the single blue*white tracer wire?

Three, I have the 2 post ballast, not the 4 post. At the "wiring harness connector" (bottom diagram), I have #2, 4 & 5 taken care of. So, I only have ONE wire left (blue*yellow tracer). Since my car is miles away right now, I don't know if this blue*yellow tracer wire is from position #1 or #3. (The green*red tracer wire is not used.)

So, I'm thinking to splice the blue*yellow tracer wire from the ECU to the side of the ballast with the blue*white tracer. And, NOT adding another wire to the (+) coil post (see reference to the red wire in the top diagram), since the blue wire of the blue/brown at the other side of the ballast is going to the (+) coil post already. Do I have this right???? I'm actually blending information from the two diagrams furnished by .emonic.

 

[abodyjoe]

So, I only have ONE wire left (blue*yellow tracer). Since my car is miles away right now, I don't know if this blue*yellow tracer wire is from position #1 or #3. (The green*red tracer wire is not used.)

it goes to the side with power in the "run" position of the ign switch. so pull both wires off the ballast and see which one has power with the key in the "run" position.

 

[abodyjoe]

diagram explains it pretty well. as long as you have an unmolested connector it boils down to just 2 wires. black/yellow to -coil and blue/yellow to the "run" wire on the ballast.. doesn't get much easier then that..

same diagram thats in the mopar performance book...

 

[DustyEd]

it goes to the side with power in the "run" position of the ign switch. so pull both wires off the ballast and see which one has power with the key in the "run" position.

I have other harnesses out right now, so I can't power up the engine harness. I think 67Dart273's info. clears up a lot of things. In the top colored diagram, the "red" becomes blue and the "yellow" becomes brown. Thus, the "blue"in the diagram must be the blue*white tracer in my case, so that is where I should splice the blue*yellow tracer from the ECU into. If this doesn't sound right, let me know.

 

[abodyjoe]

tell ya the truth i have no idea what you have so all i can do to help without pictures or more info is what i already posted. its a pretty straight forward install.

 

[DustyEd]

diagram explains it pretty well. as long as you have an unmolested connector it boils down to just 2 wires. black/yellow to -coil and blue/yellow to the "run" wire on the ballast.. doesn't get much easier then that..

same diagram thats in the mopar performance book...

View attachment 1715486835

Thank you, your diagram (2 post ballast and 4 pin ECU) verifies everything I was deducting. Really appreciate everyone's input. Back to the car I go!

 

[abodyjoe]

Thank you, your diagram (2 post ballast and 4 pin ECU) verifies everything I was deducting. Really appreciate everyone's input. Back to the car I go!

thats right from a mopar performance engines book..

 

[67Dart273]

That's the thing.........I can't really help you with colors, as they are different in some years, and "I can't see" what you have. On top of that, some of the ECU harnesses are different

There are only two underhood key-switched power sources under the hood (actually three) None of them are fused, at least in earlier years. They are:

1....IGN1 or ignition run. This is hot ONLY in "run" it is NOT hot in "start."
2....IGN2 or the brown bypass circuit, IGN2...This is hot only in start and supplies "hot" ignition power for starting
3...."Start" the yellow start wire......Goes only one place, the starter relay, and engages the starter

 

[oldkimmer]

The wire goes to the key side of the resistor. The right side when looking at it. Kim. The other side is running to the coil positive. Kim

 

[DustyEd]

Ran the 340 down the road last night. All good.

However, I did have a moment of "Wow, I can't believe I wired something up wrong!" Buttoned everything up, jumped in, took a breath, pushed in the clutch and hit the key..........NOTHING. My first thought went directly to the clutch safety switch, but not before I thought I just probably fried something. When I first got the Duster, I noticed the previous owner had a strange jumper wire from the "green wire" post of the starter relay to one of the relay's mounting bolts. I just replaced this grounded jumper with an original green wire "harness" going to the switch by the clutch pedal. The original wire is riveted to the switch, so I just spliced the new wire on the old wire near the switch. So, I reinstalled the old jumper and "POW"! (Someday, I'll have to replace the evidently defective switch.)

So, in my case, the blue*yellow tracer wire from my 4 pin ECU (from Ehrenberg) is spliced into the blue*white tracer wire of my points system engine harness (from Evans Wiring) and these go to one side of the 2 blade ballast resistor. The other side of the resistor has the blue and brown wires.

All pretty basic to most, but if this helps at least one other "shade tree" mechanic, I'm satisfied.