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1930’s and 1940’s Chevrolet Truck Typical Wiring System


Additional Points of Interest on Early GM Wiring

1. Six volt systems MUST have 2 woven wire cables as a ground to allow plenty of current flow.
a. One from the battery to the frame rail. See drawing.
b. One from the ear of the starter attaching bolt to the frame rail.

2. The insulated cable from the battery to the starter switch, see drawing, MUST be a heavy one gauge thickness. NEVER use a small diameter 12 volt cable. It cannot carry the extra current flow required
by the starter. A small cable will cause the starter to turn slow!

3. As much as 75% of all electrical troubles are traceable to poor connections in the circuits.

4. An old timer way of tracing down an electric drain in your truck:
a. Touch a removed battery cable end against its battery post. If you have a short, you will see a tiny spark due to current flow. Sometimes dim outside light is necessary.
b. Disconnect suspected areas where a short may exist. When you no longer have the tiny spark, you have found the electric drain.

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