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gebbiepress@pipeline.com

Is a 0.9 ohm BALLAST resistor the same as the resistor wire?

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I have a 1976 that has the resistor wire in the wiring harness. Measures about 9 volts at the coil with all leads connected. I also have a new bosch w0133 (made in Brazil it says) coil which says to use a 0.9 ohm ballast...is the resistor wire in the harness the same thing as what the coil calls for, or is a ballast resistor an external resistor (who knows, ceramic, amp rating, whatever) ? Thanks!

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Basically. However, you should have a relay in that circuit that bypasses the resistor to provide full system power to the coil on starting.

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Yes, the ballast resistor takes the place of the resistance-wire. In other words, the wire is just a long resistor with the same resistance as the ceramic ballast.

Like Chris_B says, make sure there is a relay that bypasses the ballast while the starter is cranking. I personally don't like the wire because it can overheat and set the car on fire, without blowing a fuse, if it shorts out.

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Guest Anonymous

Thanks guys. If I read my schematic correctly, the starter solenoid shoots a full 12v to the coil when cranking over and once started, drops it down to about the 9 volts I measured. I was just puzzled about the terminology. Ballast reminds me of old flourescent lights or something else. But hey, 0.9 ohms is 0.9 ohms.

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You are correct. "Ballast" does refer to the ceramic part in which the original style resistor was mounted- probably to provide a heat sink and protection of other parts and wires against the heat generated by the resistor.

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