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Hey guys i have a 70 f100 with a 360 c6 combo my coil has power in start position but when let off to run position lose power to coil and the I terminal only has .11 volts but 12 during starting I'm lost any help would be nice thanks guys and all factory ignition
Somewhere between the ignition switch and the coil the "Pink" wire is either broken, burned or there is a bad connection at the fire wall connector. As said before on this site the electrical system is really showing their age on these trucks.
Yeah have looked all down the pink wire and not seeing anything now I have a bigger yellow wire there are two wires in one plug in the switch and there getting hot like way hot melting the rubber hot
You may have the older ign switch that has the round pins, the rear plug it known for over heating an expand getting hotter loosing contact to the starting circuit wire that delivers the full 12+to the coil increasing points voltage.
The smaller pin area over heats so the plastic plug will have burnt marks.
Most people change them out with the flat blade type, pictured below
.
If those wires are getting that hot, you have way too much of an amperage draw going through those wires. First check to make sure all grounds are good. Battery to engine, engine to frame, engine to outside firewall. You get the idea. If that doesn't change anything, then I would take the starter to an autoparts place and have them test the starter. The brushes might be worn out, or the armature.
And also when my key touches the dash it sparks it is something I have never seen
Time to seek out the short
If not you may not have a truck to drive any longer.
Man, I disconnect the battery and not be driving until to find the problem .
Orich
Where would you start and the thicker peach looking wire is getting hot and melting it also has a tiny brown wire coming out of the switch with it the peach one says resistor wire
If you're saying it will try to run when actually cranking, but won't run when you release the key from the "start" position, I'd say you have trouble from the resistor that reduces voltage to the coil. I'm not sure on a 1970, but some earlier vehicles ran on something less than 12 volts from the coil and only used a full 12 volts during the "starting/cranking" cycle. If this is correct, maybe a smarter mechanic will chime in on my thought.
The fatter Pink wire is the resistor wire that goes to the coil+ side.
The brown or is it bluest ?
Orich
FOLLOW #16 & 640 Is your dash warning light socket open and possibly grounding some where?
That's kinda what I was thinking with the switch and the thicker wire if i just replace that wire all the way to the connector and out in a balist resistor would that be ok
That's kinda what I was thinking with the switch and the thicker wire if i just replace that wire all the way to the connector and out in a balist resistor would that be ok
The resistor wire is the pinkish fat wire coming right out of the switch plug.
And yes it will get warm being a small gauge size with just points.
But not like near melting. How old is your key switch ?
I'd pull it down & out an test with an ohm meter. Check the plug for over heating replace if burnt contacts,
Orich
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