Battery Cut Off Switch Question

I don't entirely understand the two measurements you made and your picture isn't very clear.

Scenario 1: You measured the battery from POS terminal to NEG terminal with the cutoff switch is set to off and measured 12.68V
- This is the maximum potential of the battery and the circuit is completed from terminal to terminal THROUGH the voltmeter (which is the path of least resistance for current).
- If you actually physically disconnected the battery from the cutoff switch, the measurement wouldn't change. THAT tells you that the cutoff switch is working.

Scenario 2: I THINK you measured one terminal to another
- I removed my stock switch and replaced it with a newer one so I don't remember if the stock wiring disconnects the POS battery terminal to everything downstream (aka the main fuse panel) OR if it merely disconnects the ground wire to the battery.
- I believe it cuts off the power. In that situation, the voltage potential being measured is a lot longer (aka going through the chassis) so a small voltage loss is not unexpected.


If you are worried about a parasitic loss, disconnect the wire feeding power from the POS terminal to the battery, place the voltmeter in series (not in parallel like when you measure votlage) between the battery and all the stuff downstream, and measure the amperage (DCA)
- Obviously, don't turn anything on as any real amount of current will burn out your lead wires if not your voltmeter).

Parasitic draw should be 30ma or less. If its 80ma or higher, something will kill your battery.
https://www.uti.edu/blog/automotive/parasitic-battery-drain

 

This might be a "normal" result. When you touch the voltmeter probe to the terminal of the (open) cutoff switch that connects to the chassis, it has a path of cutoff switch terminal - to chassis - to negative side of all the gizmos - thru the gizmo (if "on") - to the positive side of all the gizmos - to the positive battery terminal (and things like a radio memory would be in an "on" state). Consequently, If any gizmo is "on", the whole chassis is at the potential of the positive battery terminal when the cutoff switch is open.

 

Yes, generally normalish. By:

"Solenoid white wire at rest, disconnected (no load) at key ignition on position 11.4v"

Do you mean the voltage on the disconnected white wire at the starter solenoid is 11.4V with the key in Pos III (start)? If so, what does the voltage between the battery terminals measure during this same test? (It is not "no load" because things like the ignition system, the key services relay, the window relays, etc. would be "on".)

 

One of the mounting screws is common to one of the cable studs. If the 2 cables are attached backwards the supposedly isolated battery is still grounded via the switch mounting screw. Dumb switch design. I encountered this for the first time about a year ago.

 

If the switch is in the off position and the battery is still on the cables are reversed. You can do with that whatever you feel like.

Do you really believe yours is the only car with reversed cables? A random picture of another car is never a good example to copy.