Is this true?

mkirsch wrote:
It is supplying power to the camper BATTERY itself, not the charger!

That is, if you installed a 40A fuse in the "Stud #1" position in the fuse panel under the hood on the driver's side. From the factory, there is a dummy fuse in that position.

Your truck outputs power for the 12V DC power system. Your camper's converter/charger operates on 120V AC household power.

Clearly the truck cannot power the camper's charger, but it can charge the camper battery directly when properly configured.

My "stud #1" position has a 30A fuse that does not appear to be a dummy.
It is labeled as trailer brakes.

I will have to check with a volt meter if I can figure out how to do that.
Zulu

Some GM trucks require termination of a wire either on pin 1 or 2 depending on the year, then the installation of the 30 amp fuse.
I would suggest installing a relay to isolate this circuit to prevent running down the truck battery.
A good example with instructions is this one from Tekonsha.
Battery switch

donn0128 wrote:
GMs require you to install the 30A fuse replacing the dummy fuse in the under hood fuse panel. Is your camper teathered to the truck via the 7 pin plug?

Yes, a 7pin plug.

I'll have to check for the fuse.
Zulu

A quick way to test is to use a DC VOLTMETER on the battery terminals without shore power or generator running. If the battery is fully charged it will read 12.6-7VDC

Then start your truck motor and if the Dc VOLTAGE across the battery terminals jumps up to 13.6VDC then this will be telling you the truck alternator charge voltage is making it back to the battery terminals...

If it doesn't show an increase in DC VOLTAGE then start looking for some of the things said above...

In my case I had to install a RELAY and a FUSE that in my truck glovebox in an unmarked envelope. In the truck manual these items were identified as trailer tow fuse or tow relay or something like that.

However don't get too excited as in my case the charge voltage coming from the truck alternator would give me 6 amps or so of DC CHARGE which is great to have but will not re-charge a battery very quick. It is more of a top off charge.

Roy Ken

GMs require you to install the 30A fuse replacing the dummy fuse in the under hood fuse panel. Is your camper teathered to the truck via the 7 pin plug?

It is supplying power to the camper BATTERY itself, not the charger!

That is, if you installed a 40A fuse in the "Stud #1" position in the fuse panel under the hood on the driver's side. From the factory, there is a dummy fuse in that position.

Your truck outputs power for the 12V DC power system. Your camper's converter/charger operates on 120V AC household power.

Clearly the truck cannot power the camper's charger, but it can charge the camper battery directly when properly configured.

As far as I know all pickups have that option for last 100 years ;)
Some models require inserting fuse, some need big plug installation, so check the manual.
On my Fords I don't need to start the engine.
Just turn the ignition on. I used the option when running compressor on my equipment trailer.
The small trailer battery for break-away brakes was too small to power compressor at 90 psi.