74 duster electrical problems
Even though the wiring is now different, you need to download a shop manual from over at MyMopar. Several of those, by the way, came from this site
Resisance values for the coil and distributor pickup is in those. I would at least download the 72 and 73 manuals, they are a great reference, and the 73 manual contains the newer front disk brake info
It is disturbing that you are blowing that one big fuse, but not something in the panel. This either indicates a short that is not related to the panel, or that the fuses in the panel are way too large. One "big" thing that can cause a short such as that is the alternator
But since you seem to have burned up these items, I would lean towards they are over fused individually, or somehow got wire WITHOUT being fused.
The problem is, not knowing how the car is wired, I can only guess
Again, immediately measure voltage of the thing charging so you know "where that is."
So far as testing a Mopar ECU you can "jig" it up "on the bench."
Even though the wiring is now different, you need to download a shop manual from over at MyMopar. Several of those, by the way, came from this site
Resisance values for the coil and distributor pickup is in those. I would at least download the 72 and 73 manuals, they are a great reference, and the 73 manual contains the newer front disk brake info
It is disturbing that you are blowing that one big fuse, but not something in the panel. This either indicates a short that is not related to the panel, or that the fuses in the panel are way too large. One "big" thing that can cause a short such as that is the alternator
But since you seem to have burned up these items, I would lean towards they are over fused individually, or somehow got wire WITHOUT being fused.
The problem is, not knowing how the car is wired, I can only guess
Again, immediately measure voltage of the thing charging so you know "where that is."
So far as testing a Mopar ECU you can "jig" it up "on the bench."
You need a coil, the ECU and the distributor
Lay it out on the bench. Follow the diagram. Find the two distributor pickup terminals on the ECU. Hook them to the distributor
Hook the ECU case to battery NEG
Coil does NOT need grounded
Distributor does NOT need grounded.
Hook coil + to the power lead terminal on the ECU. Get a clip lead hooked there and let dangle. This is your battery "hot" when you are ready
Hook something from coil "case" to a probe for testing spark.
Hook up your power clip lead. Twist the distributor shaft while holding the test probe near the coil tower. The thing should make sparks
If not, unhook distributor. Take first one, then the other pickup clip leads, and "tap tap" ground them at the battery connection. Coil should make 1 spark each time you do so.
If not, try another coil. If that does not fix it replace the ECU
IF you hook it all up and it WORKS, then there is something AFU in the car harness. SUSPECT a bad ECU connector OR a bad DISTRIBUTOR connector
=============================================
This is all you need to test the basics of the ignition. You can easily test the ballast separate. A battery, the ECU, distributor and a coil, and of course some test leads
Below, the basic diagram for a 4 pin ECU
Below, the wire for testing spark. I use my 12V test light. No, LOL the spark won't blow up the bulb
Below, the ground connection. ALL you need is one wire from batt NEG to the ECU case
Below, the two distributor connections. In the car these are polarity sensitive, but for testing does not matter
Below, the coil NEG connection
Below, battery PLUS connection, one wire to this terminal of ECU and jumpered over to + side of coil
Below, all hooked up and ready to test. Should produce sparks at least 3/8" and typically 1/2" long
Below, distributor "one wire" test. I have removed the other distributor wire for simplicity. Take the bare connector end or this clip lead (the yellow) and with everything hooked up, ground it repeatedly. Each grounding should result in a spark (In this photo you need to hook up the ECU ground wire, I left it off for the photo)
