Delete

Delete, I was wrong

 

Orientation of the add a fuse shouldn't matter. The fuse isn't directional, so it can be put in either way. It is weird that both sides are seeing power, but I just hit mine with a DMM, and it shows the same results.

 

Could depend on what that location is intended for. It could be a ground switched item similar to the dome light. In that case you will complete the circuit any time you connect a meter to it regardless of which side you are on.

 

If you need to know your supply side remove the fuse !!

Measure from one side to ground then do the other the supply side will show system voltage

 

If your fuse is removed and both sides read system voltage to ground something is wired wrong

one side should be your voltage supply

the other side is your load

Is your whole fuse block doing this??

Just this one circuit ??

 

In your first video clip it looks like the voltage never exceeds 11.7Vdc. That seems low since fuse panel voltage should be very near battery voltage. What do you measure on other fuses on that panel and across the battery? If the battery is fully charged with the rig off you should measure something closer to 12.6Vdc across the battery and at the always on fuses. Also take a photo of your multimeter with the leads attached and in the measurement setting you were using so we can verify that is correct.

It doesn't make sense that both sides of the fuse location measure hot. Only one side should measure near battery voltage with the fuse removed. Something isn't right.

As you mentioned orientation of the add a fuse does matter if you don't want to overload the truck's wiring. With the add a fuse installed into the fuse panel, but with the "original" fuse not installed in the add a fuse the added circuit should not get power. If it does the add a fuse assembly needs to be flipped around since all current needs to flow through the "original" fuse first then the added fuse second.

 

What is that fuse for? Does what ever it powers still work with the fuse pulled?

 

Windshield washer pump

 

It really depends on the wiring of the circuit in question. There could be some bleed-through from some common adjacent circuit...not necessarily enough to power your circuit, but enough to raise the potential. What really would matter is if you can still run the circuit that the fuse powers without the fuse actually being inserted. If that's the case, then something is very wrong and you should figure it out.

However, if the circuit doesn't work with the fuse removed, then you are probably ok. Just because a voltage is present, it tells you nothing about the current or power it will be able to deliver. If I were to take a 100K ohm resistor and put it on the positive terminal of my battery, the other side of that resistor measured to the negative terminal of the battery would measure about 12V. However, the most power I could possibly get out it would be 12 micro amps...which would be 1.44 milliwatts...which you wouldn't be able to do anything with.

Anyway, the only real way to determine if there is a problem is to look at the wiring diagram for the circuit in question and see if it makes sense for a voltage to be present. But if others measure the same thing, you're probably ok and you shouldn't worry about it.