IGN2 issue

[Jeff Erwin]

Converting my 71 charger to a single-wire alternator. All new harness front to back. All connections triple-checked and all connections soldered. No shorts. Engine turns over, won't fire.

I have a sparker on the top of the coil, no spark when cranking. However, I get a spark when I turn the key back to 'run' and the engine coughs once, so IGN2 circuit appears to be doing what it is supposed to do. The brown wire from the steering wheel harness has solid connection to the plus side of coil.

To diagnose the IGN1 circuit, which I believe supplies current to the coil when the key is in the 'start' position, I run a wire from the battery positive to the plus side of the coil. Still no spark, which make zero sense. Still get the single spark and a cough when I turn the key back to run.

Busy ohming out the IGN1 wire from the steering console, but am wondering if there is something else going on I am not getting. Battery is fully charged, can't be the new alternator because of the single spark I get in the run position. I suspect I get the single spark because the alternator isn't turning and doesn't produce enough to keep it going.

What gives? What else should I be checking?

 

[Rockland71GTX]

Ignition 1 is the blue wire which should be hot in the 'run' position. Ign 2 is the brown wire which is hot cranking.

 

[66chargerpat]

Blue is ign1. Brown has power in crank position. Blue has power in run position.

 

[Rockland71GTX]

If you don't have a service manual, you can download one here for free: Service Manuals – MyMopar

 

[Jeff Erwin]

The shop wiring diagrams and American Wire docs disagree but I know I have that part right. In any case putting 12v from the battery to the plus side of the coil bypasses all that. I’m starting to suspect the coil so replacing it now.

 

[Don Frelier]

It could also be your point gap or condensor.
Does the distributor have a good ground?
You probably didn't change any of that while you were working on it correct?

 

[Jeff Erwin]

It's an electronic ignition, standard MOPAR issue.

I think I have it narrowed down to the coil or ESU unit, have ordered both.

Anyone know what the resistance should be between - and + on a coil that isn't hooked up to anything?

 

[383man]

It's an electronic ignition, standard MOPAR issue.

I think I have it narrowed down to the coil or ESU unit, have ordered both.

Anyone know what the resistance should be between - and + on a coil that isn't hooked up to anything?

Average coil that we use on the Mopar ign would be around 1 ohm on the primary which is the + and - terminals. Secondary winding around 10,000 ohms and go from the + to the coil wire terminal to the dist. Thats just average as without knowing the coil you have thats a ballpark for average coils on our older cars. If its an MSD coil it can be much different. But I can also say over my 40 years as a tech I have had coils not work or have weak spark that still had good ohm readings. Also if you said you get a spark when you turn the key back then the coil is working. Try turning the key to run and then jump the starter and see if it runs. Ron

 

[What’s up dock]

When you say all new harness front to back, I think of the bulkhead connector. I've seen many replacement engine harnesses that were pinned wrong. Verify that the correct pin is getting juice in the bulkhead in the start position. Same goes for the wiring to the spark box, which will feed the ballast. Also, if it's fresh paint in the engine compartment, make sure your spark box has a good ground to body.

 

[HALIFAXHOPS]

A dual ballast resistor can do that also.

 

[Jeff Erwin]

An excellent idea! I never thought of that, I was actually trying to turn the key back to 'run' quickly to see if I could get the engine to catch. I have a new coil coming in this morning, but will definitely try this as well if that doesn't fix whatever the issue is.

 

[Jeff Erwin]

I have used my continuity tester to make sure the wires coming from the steering column harness go all the way to where they are supposed to do. No issue found.

This will, of course, turn out to be something stupid I did, but until then...

 

[383man]

I have used my continuity tester to make sure the wires coming from the steering column harness go all the way to where they are supposed to do. No issue found.

This will, of course, turn out to be something stupid I did, but until then...

We all get jobs that end up being something we figure we should have got all along. One time I was checking a charging system on a Malibu as I was jumping the alt field to check for alt output and then I finally saw the alt belt was gone !!! Doh did I feel dumb but I just did not think it was going to be that simple. Good luck with yours and keep us posted on it. Ron

 

[JDmac72chrgr]

Did you do resistence (ohms) check of ign switch at run & crank?? Found original run continuity would be different each time placed in position