Check this out:




The first schematic is the electronic ignition system for a 74 Dart, taken from my FSM on CD. In the second schematic I modified it slightly at the ballast resistor to show how the wires are actually connected on 74DartSport's car. I've been trying to help him track down the problem he is having with the car not starting.

You can see that his Blue/Yellow wire from the No. 1 pin on the ECU and the Dark Blue wire (presumably from the I1 terminal on the ignition switch) are switched from what the FSM shows. Can someone explain this? Could this be the reason for the non-starting problem?

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There's a difference between ignorance and stupidity.
Ignorance is not knowing any better.
Stupidity is knowing, yet doing it anyway.

No that wouldn't cause it not to start since they are tied together with the short jumper. Did you replace the resistor? That is usually the problem.

Get the volt meter out and be sure you have a full 12 volts at the blue wires and hopefully at least 6 volts on the brown side depending on the resistor it can read higher. Make sure you read the same voltage at the coil.

Be sure the ECU box is well grounded or it won't start. I run an extra ground wire to the case just to be sure.

Once you get it running......On my 74 I rewired it to use a single style resistor instead of the dual. On a 74 you don't need the green and red to pin 3, so it makes it pretty simple to run a single resistor.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Randy (74DartSport) also said there is only one brown wire coming off the ballast's terminal where you see two connected on the schematics. I'm guessing the second brown wire is solder-joined somewhere along the wrapped harness out of sight. Anyone else have just the single brown wire visible from the ballast like his?

_________________
There's a difference between ignorance and stupidity.
Ignorance is not knowing any better.
Stupidity is knowing, yet doing it anyway.

Ted, Jerrys diagram is just as I described it to him. We were concerned that my blue/yellow on the ballast was reversed with the dark blue. According to all FSM and mymopar.com drawings Jerry and I have looked at, the red/green and blue/yellow should be on the auxillary side of the ballast resistor and the dark blue wire and the brown wire going to I1 and I2 of the ignition switch, respectively should be on the compensating side of the ballast resistor.

The ballast resistor is brand new. I have 12.19 volts at the battery terminals. With the key in the on position, yet not cranking, I have 10.45 volts at all four terminals on the ballast resistor. You say I should have 12 volts on the blue side and at least 6 on the brown wire. How do I proceed? Ask away and I will answer.

And yes I have run a ground wire from the ECU to the body under the left front fender. I also installed an extra ground on the voltage regulator on the passenger side fender well.

Is 10.45 volts at all four terminals okay?

I have from top left going counter clock wise 10.97, 10.97.6.94.1.98
Hope this helps
Frank
PS 74 Duster stock

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Scrapple: Because a mind is a terrible thing to waste.
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66 Dart Wagon - DD
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82 D150
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If you've only got 10.45 v at the ballast, you've most likely got yourself some corroded connectors. I've cleaned mine up on cars that I have had, and other than the ignition switch itself, I was able to get exactly 12 v to the ballast, with a battery reading 12.6 v.

With 10.45 the car should still start, just keep in mind the system won't be working the best it can. If you have 10.45 v on all connectors, I would take an ohm meter, and check the resistances of the ballast with all 4 connectors off. Then rewire it to match the factory schematic. Even though it "should" work either way, I prefer to have it wired exactly per the manual, so there is no question.

You should as others have stated have near battery voltage on the feed side, and lesser voltages on the other. If the ballast checks out ok, I would start looking for shorts to power or miswirings to power.

Interesting....

~THOR~

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