Challenger stopped starting

[06Daytona]

This morning the Challenger won't start. I have lots of juice in the battery and I have power going to the big red wire under the dash. When I turn the key to start the voltage drops to almost 0 on the red wire and I only have enough juice going through the yellow wire to make it twitch a little, which is probably the same amount showing on the red wire . If you're not looking at it you don't even notice it's moving.
I'm not sure if it's a ground problem, or a starter relay problem, so I'd like a few opinions about what to look for before I waste a bunch of time looking at things that don't need looking at.

[GranCuda1970]

Any noises clicks when you turn the key or is it completely dead.

[06Daytona]

Completely dead. And I believe everything else is dead in the car too

[GranCuda1970]

The lights wont come on, if they do do they dim when you turn the key?

[GranCuda1970]

Service manual has these listings for Failure to start. weak cell or dead battery cell, Ignition switch faulty, loose or corroded battery terminals,Open circuit wire between ignition starter switch and and terminal on battery relay.

[johannes]

Test proposal;
Run a decently thick cable from main alternator output (Thick cable) to battery +

By doing this, the power will take another  bulkhead connection path than it normally does.......

Any luck?

JB

[06Daytona]

There are no lights. I changed to a different battery and I have the same voltage at the battery and the big red wire. I bypassed the firewall connector since it was looking a little corroded on the inside and thought it might be part of the problem. I have good voltage where the new wire connects to the old one and then goes up behind the gauges, but the red wire that comes back down has less voltage. Unfortunately it's all wrapped in black tape, so I can't check all the way along. When I check continuity it reads fine, but I might be doing something wrong when I'm reading it too.
I have a wire running from my alternator to the large connector on my starter relay from an earlier electrical problem, so I hooked that back up. I'll try running it right to the battery next though.

[GranCuda1970]

I'm wondering if the ignition cabes are faulty. Just says to replace cracked or shorted cables.

[dodj]

If you turn the key and your voltage drops to zero on the red wire feeding ign sw., you have a short to ground and should have blown a fuse/fuse link if the battery voltage is going to zero as well. That kind of current will melt your plastic connectors. If the battery voltage was staying up, you have corroded connections somewhere. If it was me, I would definitely check what the voltage at the battery is doing when you turn the key.

[06Daytona]

It turns out was a bad starter relay. I changed it out with a spare I found and the lights work and it tries to turn over. It chatters but won't turn over (it's not a low voltage chatter, it's a something broke chatter). If I roll the car back a few inches then crank it it turns over fine. I have a feeling that my flexplate may be broke, or the ring gear is shot. I just picked up a mini starter for the 440 so I might pull the view plate on the trans and see if I can see anything, or else I just wait for my cam to get here and leave the car until it's got the 440 in it.

[dodj]

Check your fusing/fuse link in the engine compartment. Your bad solenoid was the source of the short, but when that device shorts, you should have opened a fusible link. Just something to check to make sure you are protected from a short circuit caused fire. 

[06Daytona]

It's back. When I turn the key I get nothing, but I can get the engine to crank over by jumping the two contacts on the starter relay. It won't start, even when I pour gas into the carb, but at least it's cranking. I'm hoping that the problem is either starter, or something that's going to get changed when I drop in the 440

[GranCuda1970]

I forgot do you have the automatic tranny?, do you have the heat shield? I went through 3 starters because i did not have the shield. in a 2 month period. Also just check to make sure your getting 12 volts off the alternator mine wasn,t it had hard start symptoms.

[06Daytona]

It's an auto. I'm not sure about the heat shield since I haven't spent much time under the car. I have headers on the car if that makes a difference. I'll check for 12v off the alternator again, but last time I checked I did.

[GranCuda1970]

Here it is

     http://www.cuda-challenger.com/cc/index.php?topic=79479.msg799539#msg799539

 I would wrap the starter and header next to the starter with heat wrap.