79 Bronco 400
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- Dec 12, 2009
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I have a 78 F150 that I'm having electrical issues with. I was driving down the road about 3 weeks ago and all of a sudden the truck just shut off!!! After troubleshooting and researching for 3 weeks now I think I've narrowed down the "where" the problem is, but I don't know "what" is causing the problem, which brings me to this site asking for help....
What I found was with the key in the "on" position (engine not running), the wire that goes to the coil + is only reading 3 volts, which is why I assume the truck won't start. From what I understand with all the research I've been doing, there is a "resistor wire" in the wiring harness that reduces voltage to the coil.
My questions are:
1) Tell me if this is correct....At the coil + wire, there should be 12 volts when cranking the motor, about 7 volts with the key in the "on" position, and about 9 volts with the engine running?
2) If the resistor wire went bad, would it cause this low voltage problem I'm having with the coil + wire with the key in the "on" position (3 volts instead 7 volts)?
If the resistor wire is not the problem, can you tell me why I'm not getting hardly any voltage at this wire with the key in the "on" position? The ignition switch is brand new (I replaced it thinking this was the problem). I have a MSD 6A ignition box and an Auto Meter tach hooked up and it won't even turn them on when I turn the switch to the "on" position because of lack of voltage in the factory red/green coil + wire.
Any advice or thoughts is greatly appreciated. Thanks...
What I found was with the key in the "on" position (engine not running), the wire that goes to the coil + is only reading 3 volts, which is why I assume the truck won't start. From what I understand with all the research I've been doing, there is a "resistor wire" in the wiring harness that reduces voltage to the coil.
My questions are:
1) Tell me if this is correct....At the coil + wire, there should be 12 volts when cranking the motor, about 7 volts with the key in the "on" position, and about 9 volts with the engine running?
2) If the resistor wire went bad, would it cause this low voltage problem I'm having with the coil + wire with the key in the "on" position (3 volts instead 7 volts)?
If the resistor wire is not the problem, can you tell me why I'm not getting hardly any voltage at this wire with the key in the "on" position? The ignition switch is brand new (I replaced it thinking this was the problem). I have a MSD 6A ignition box and an Auto Meter tach hooked up and it won't even turn them on when I turn the switch to the "on" position because of lack of voltage in the factory red/green coil + wire.
Any advice or thoughts is greatly appreciated. Thanks...
