70 Charger has ign. problem, suggestions?

[jlatessa]

Son was driving our 70 Charger RT Sat. (we keep it at his house)
Gave me a call, said car died after a "POP", car would try to restart then die when key released.

I assumed ballast resistor and took a ride to where he was with a spare and my Fluke.
Well, resistor checked OK and new one didn't help.

Found a 15 A fuse blown, replaced it but same results. Had car flat bedded to his house, $90, not too bad.
I'm thinking ignition switch or shorted wire before the ballast??

So what would be the best way to test wiring tomorrow with my tester?
Charger has a Painless system we installed, been about seven years with no hiccups.

Thanks in advance, Joe

[Nacho-RT74]

It can be either the ballast, the bulkhead or ign switch itself.

If/when you don't have a tester you can feed the ballast straight from batt up to the blue wire side ( with a jumper wire ) and try to crank the engine. If starts up, the ballast is good, so that takes up to bulkhead at RUN circuit wire ( blue )  or ign switch. Of course will need to remove the jumper wire to turn off the engine.

If making that jumper, your brake light on cluster turns off while cranking, that will confirm a failure either at bulkhead or ign switch. The brake light on cluster should dimm out while cranking, since it gets feedback powered throught the ballast when ign2 ( brown wire ) is feeding the engine.

Also, if your brake light doesn't turn on when the key is in RUN, definitelly the ign switch is the culprit, not the bulkhead, since the RUN circuit comes straight from ign switch to feed that light. As far the emergency brake is applied of course.

This applies the same when the oil light is present on standard clusters, which is not the case on the 70, but for example, 3rd gens with standard clusters.

This is of course on stock system.

[jlatessa]

Thanks Nacho, what I expected to hear.
No bulkhead with Painless, so that narrows the problem.

Since the fuse was blown, I'm suspecting the switch or the wiring past the fuse.
Reasonable logic?

Thanks, Joe

[Nacho-RT74]

stock system doesn't have fuse for the Ign1 circuit... dunno ¨painless¨( LOL ).

But, yes, reasoneable logic

[John_Kunkel]

Found a 15 A fuse blown, replaced it but same results.

Is that fuse in the central fuse panel? If so, what system is labeled to protect? Does that Painless system incorporate both the IGN1 and IGN2 circuits?

[jlatessa]

My mistake, that fuse was domelight protection, never chased the problem.

So I'll figure it out with the meter, son was not well today, he's the only one who can still
get under the dash and out by himself, hopefully tomorrow.

I found the old switch and leads in the basement, The big red wire was frizzled,
but it may help me to diagnose.

Thanks,, Joe

[Kern Dog]

Remove the seat. It takes a few minutes and really makes the job easier.

[jlatessa]

Found it! Open blue wire to ballast.
Wire got damaged apparently when we were using 12V supply from the blue for a trans temp. light.

All is good now.

Thanks to all for input...Joe

[Nacho-RT74]

cool! love easy fixes!