Ignition switch question

[kipps]

Attached is a diagram of a squarebody ignition switch. Note it has Battery 1, 2, and 3. Are these terminals internally connected, or are they each feeding an independent switch?

I'm hoping they're independent. I'm attempting to use the '87 dash controls to operate a 2010 harness and fusebox. The snag is that the 2010 is switching the fusebox relays from the body control module, which in most cases is switching the ground. Sometimes though, it's switching the hot, so I'm wanting to operate a ground and a hot switch within the stock '87 ignition switch.

[VetteVet]

You should be able to tell with a simple continuity check between the three terminals with the key off.

The key switch has a ground terminal and it is also grounded through the body. This is most likely happening when the start position is selected which will ground some test light circuits to check the bulbs I.E. brake warning and temperature overheat lights. This would be a carryover from the earlier years with the light dashes. It might also ground the bulb circuits when the key is turned to on for the check engine lights, oil light, Bat light, etc. That will go off when the engine starts.

You can easily run a separate grounding circuit by just tapping one of the three Bat terminals to a separate relay which connects a ground source to whatever you want to be grounded when the ignition is on.

This would leave your BCM to do it's thing with the 2010 harness.