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Body on Frame cars

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I just watched the Body Ground section, and while it makes sense for unibody cars, I'm building older body on frame cars, which are generally isolated by rubber bushings as well.

In this case, is it safe to go:

Battery > Frame

Battery > Engine

Frame > Body

Battery > ECU (via distribution block)

thinking about the earth circuit and making it complete, clean and capable of doing its job yes it is ok to do that

You will find that while there will be 6-8 isolators for the actual body to chassis, there are many other places there is direct contact made via body panels, etc.

With older 'clockwork' ignition, either method works well, usually battery to engine to body.

However, with electronics even a very small variation in voltage potentials can cause problems, so it may be advisable to use only the engine as the ground for all the electronics and associated senders, to avoid any ground loops that may arise from the body having a slightly different 'ground' voltage.

If it's a fibreglass car, like a Corvette, you're going to have to ground everything not related to the engine to the chassis, of course.