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Old 04-19-2014, 07:52 PM   #5
VetteVet
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Join Date: Jan 2005
Location: Kalamazoo, Michigan
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Re: Problem with ignition wiring on 1972 C10

Here is a diagram of the ignition from the engine side of the firewall block to the coil. The orange white purple wire is a resistance wire that prevents too much voltage to the coil during normal running.

It ties into the yellow wire from the starter which supplies 12 volts to the coil only during starting. After starting the 12 volts on the yellow wire drops to 9 volts due to the resistance wire.

Check your coil positive terminal for voltage with just the key on. If you have it then the coil is bad or the distributor is the problem.

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The orange white purple wire is a cloth covered wire but due to aging it may look like this.

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It is right next to the no.2 blue wire.
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