Crank - no start

[euroZ06]

Hi all,

So im dealing with something that should be simple, but I'm not exactly sure how to fix it. 68 Charger 383 with MSD ignition.

Long story: I was accepted to a fancy car show, and the day before, I went to wash the car and the car wouldn't start. I started checking everything, only to find I wasn't getting a spark. So I figured either my MSD ignition box was fried or MSD ignition coil. I went out and bought a new system, but same result. The new MSD box has an LED light that lights up when the ignition is on and should be flashing when cranking, and I noticed that the light goes out when cranking, which means it gets the power to turn on when ACC is on, but once I start cranking, the box is no longer powered. To get to the car show, I hotwired the box directly to the battery, and the car started and ran no problem. So upon returning home, I started checking, and this is what I have:

I have a new alternator with a built-in ballast, so the one on the firewall isn't used. The system was wired to receive the 12V ACC from the blue/white and brown wire that are connected together (my understanding its ignition wires that used to go to the ballast). That same wire where I used to get my 12v also runs to the alternator (also connected to the ignition wires). I checked my firewall connections (took out the connector, cleaned it up a bit, nothing jumps at me to be wrong/old). When I put ACC, I'm getting 12V at the blue/white wire and 0v at the brown wire. Once I start cranking, both blue/white and brown wire are only getting 4v (which isn't enough to power the ignition box). So the question is: where did I lose the voltage? Is it possible some ground wire is bad? where would ground wires be for this (ground at battery is ok, I can hotwire the ignition box to the battery and everything works just fine)?

One curve ball, but not sure if relevant. I recently put in a high amp alternator (direct replacement for my old alternator, but old alternator wasn't high amp). This alternator doesn't seem to work well (lights dim/fluctuate when at idile/low rpms). I already spoke to the manufacturer and sent them my old alternator to be upgraded to dual pulley. Since I have a wire from ignition wiring running to the alternator (same wire feeding the ignition box), could the alternator be doing some weird draw of power when I'm cranking? Should I somehow disconnect the wire running to the alternator to eliminate it as the cause? i don't want to burn anything up by disconnecting the wires lol.

I have some pictures of all this on https://www.forbbodiesonly.com/moparforum/threads/emergency-help-crank-no-start.260702/#post-912435029 (not sure if allowed to post)

[metallicareload99]

Definitely sounds like there is an issue with your ignition switch. As far as the wiring to the alternator, I'm curious as I have mine wired similarly and I don't *think* it's a problem

[euroZ06]

hm, so the ignition switch can give off low voltage? is there a way to check the ignition switch? is there a ground that ignition switch connects to? Where does ignition switch gets it power? its a bit hard for me to get under the dash, i don't see much there (except of bundle of closed wires)

I was reading somewhere, and maybe I don't understand this correctly, that you can run if from the + post on the coil?

[70 sublime]

The igntion switch is a mechanical thing that moves and gets worn
When it gets worn the electrical contacts do not push together as hard as they used to to make a good circuit

Try cranking to start the car with the key and push in on the key and wiggle it around a bit when trying to start the car and see if it makes any difference

[XH29N0G]

Others will have better suggestions, but I will share my experiences in case the help.

I have two quick checks and then a more laborious one.  The ignition switch plugs into a plug under the dash.  Check to make sure all of those pins are making the connections they should be.  I had that plug be a problem on my car.  I assume just because it was old.  I also bought a replacement ignition switch.  It will plug into that and can be used to see if the igntion switch is the problem. 

If neither of those work, I think you are then on to the laborious process of tracing out where the wires go and figuring out where the continuity is broken.  For this, it is a pain for someone not versed in electrical diagrams like those in the factory service manual, but it is possible to trace them out on the diagram and then in the car.  I checked those with a multimeter for continuity, and sometimes for voltage. 

I have not had this problem for a number of years, but if you don't figure it out and someone else doesn't have an answer, I would be willing to look for/scan the images and see if I could figure out where the lines go.  I have not done this for a long time so it will probably take me a long time if that turns out to be needed. 

I am not logged on all the time, but enough that I will see messages either in the thread or as PMs.

BUT I emphasize that I am not the expert on this stuff.  there are people here who know way more than I do.

good luck

[euroZ06]

thank you for all the advice. I'm trying to gather all the info that I can before I go work on the car on the weekend.

My car was fully restored about 7 years ago, so it seems like all the components are fairly new (aside from mostly original wires). The ignition doesn't appear worn, and there is no play in it. But I will try jiggling it when starting, perhaps something did come loose.

Is there an easy way to access the ignition? I looked under the dashboard, and i can't really reach the ignition block, there are a lot of things in the way (do I have to remove the dashboard to get it out?)...

So my understanding is that the blue/white wire gets 12v from the fuse box when ACC is on? Perhaps one of the fuses is faulty? I just ordered a new set of fuses. But i am getting 12v on ACC, so if only the blue wire goes to the fuse box, then fuses are fine, right? Where does the brown wire get the 12v during cranking? Is it when the ignition switch connects it to the blue/white wire? So then if the ignition box is worn out, it would make sense that its not getting the full 12v.

[euroZ06]

p.s. i do have the repair manual, but since i no longer use the ballast and no longer using the original ignition system, i can't find a way to test it properly. I'm sorry, I'm not very good at electrical.

[XH29N0G]

I found it a learning curve myself and my car also had been recently restored when I ran into the problems I had.  I am attaching a picture of an ignition harness like the one on my car.  The picture is from classic industries, but I think I bought the harness from a local auto parts store.  The white connector that is circled is where the connections were not being made with mine.  What happened was that the metal pins that go in the white connector had gotten old, moved around, pushed around, and no longer made good contact.  When I finally looked at the old connector I was able to get an idea of which ones were not making contact or were making intermittent contact and I managed to expand, push, pull them so they would seat well and make good contact.  In the end I did not use the new switch.

I think I have had similar issues with other connectors in line to the ignition.  The ignition needs to be hot when it is running and when it is cranking.  In one case, I had it lose connection when running (intermittent).  In another case, the problem happened only while cranking.

[euroZ06]

So an update... after going through all the wiring, and all the fuses, i finally pulled out the ignition lock (btw i found info that the handbrake light is also a good indicator if 12v is giving during acc on and crank), and found that one of connections (on the brown wire) was reaaaaaaly bad (had green stuff all over it). I cleaned it, and everything works!!!

So i removed my newsd box, rewired the old one, now have to stuff the ignition lock back in (it was a bitch to get out, everything is super tight back there). Such a relief though, and so much more that ive learned about the car

Id post a pic, but format here is too tricky...

Thank you all for good advice!

[XH29N0G]

Great to hear you solved it.