74' Stock Starting Problem

[Phil Munsterman]

Guys,
I just picked up a 74 w/ 302 and factory wiring. When I turn on the Key I'm not getting 12 volts to the coil, the engine will crank over but not fire ( the PO ran a jumper wire from the battery to the coil and it will start and run with that but, to shut off the truck that has to be disconnected )

1) Should I get 12 volts at the " I " post ( brown wire ) of the solenoid when the key is on ?

Thanks, Phil

 

[69red]

the I terminal only gets power when the key is turned to start, no power when in run.

could be the ignition switch itself, thats where I'd start.

id check all the fuses too.

 

[broncodriver99]

Could be the ballast resistor as well.

 

[Phil Munsterman]

Could be the ballast resistor as well.

Is there a way to test the ballast resistor ?

 

[Phil Munsterman]

the I terminal only gets power when the key is turned to start, no power when in run.

could be the ignition switch itself, thats where I'd start.

id check all the fuses too.

Thanks I'll check that.

 

[broncodriver99]

Is there a way to test the ballast resistor ?

The stock ballast resistor is built into the wire from the ignition switch to the coil. If you have power at the switch terminal but none at the coil then you either have a broken wire/terminal somewhere or the resistor is burnt up. If you have no power at the switch terminal then the switch is bad.

Here are some great wiring diagrams made by seabiscuit68 that can help you track down the problem. http://seabiscuit68.tripod.com/

The ignition coil and switch are on the 73-74 pages 01-05 and 06-11.