So. Yes the tests are to isolate and narrow down the problem.
What this one shows is there is resistance in the highlighted path.
View attachment 1715734196
I'm trying to understand where the probes were on this one, and was this also during the headlight on test.
Is this where the probes were?
View attachment 1715734241
If so, then that is one step closer to identifying the location(s) of resistance.
Then check the first section (because its easy)
View attachment 1715734246
What you check next depends on a what you can access.
For example, you have long wire leads or maybe an aligator clip and some long wire, I've done this.
View attachment 1715734249
It can also be done by using the ground as reference. Use the same ground for both positions. Or at least what should be the same, like the body sheet metal.
View attachment 1715734253
Compared to inside.
View attachment 1715734255
IF you find the 2.4 voltage drop is all in the sections just tested, then there is no reason to access the more difficult to reach ammeter connections.
There may or may not be poor connections in the ignition switch, its connector, or the firewall connectors. What we are seeing is there is a significant issue before the electricity gets to the column connector or fuse box. We can't use the battery as a reference for testing when the votlage is dropping before it even gets to the main splice.
