Wiring question 1975 Dodge Power Wagon

[Phyphor]

Ok, my friend's 1975 power wagon will not fire up when you hold the key in the start position, but when you let it drop to run, it'll sometimes fire up.  I researched this and found that this is likely the bypass circuit (which energizes the coil while the key is in the start position.)

I've seen sources that say the wire is a brown wire or a pink one.  Does anyone know which one it is for the 1975 model?

Is there any kind of ballast resistor inline with this?  Does the wire change color once it passes the firewall?

[geronimotwo]

sounds to me like it's a bad ignition switch.   

[Triphammer]

There's a white, 1/4 or 3/8 " square about 2 - 21/2" long ceramic resistor on the firewall. It's the ignition system resistor. Smack it with a screwdriver handle & try again.  That resistor is the bain of Dodge owners everywhere.

[Hawkmoon]

There's a white, 1/4 or 3/8 " square about 2 - 21/2" long ceramic resistor on the firewall. It's the ignition system resistor. Smack it with a screwdriver handle & try again.  That resistor is the bain of Dodge owners everywhere.

But if the engine will run with the key in the RUN position, that ballast resistor is NOT the problem. Don't touch it, or you'll break it.

The ballast resistor is used to reduce the voltage to the coil from 12 volts (nominal, actually about 13.4 volts) to about 9 volts for normal running. When the key is turned to the START position, there is a bypass circuit that's supposed to send a full 12 (13.4) volts to the coil, to facilitate starting when the battery is working hard to just crank the engine. The ballast resistor is NOT in the circuit during starting.

So the suggestion that the problem is in the starting bypass circuit makes sense, but I don't know where to start troubleshooting it.