I killed my batteries dead after forgetting to unplug the RV trailer from the truck.

So dead the lights in the dash wouldn't light...

Had to change a battery afterword, will disconnecting the battery terminals cause the GM ECM reflash to be lost and therefore have to be reflashed again ?

nope, it should not affect your stored ecm programs.

Excellent thanks....... wasn't sure. Glad to know that now I can relax...

I killed my batteries dead after forgetting to unplug the RV trailer from the truck.

So dead the lights in the dash wouldn't light...

Had to change a battery afterword, will disconnecting the battery terminals cause the GM ECM reflash to be lost and therefore have to be reflashed again ?

When your truck is turned of, your RV trailer will not use your truck battery,
you have truck battery problems.:rolleyes:

When I got my '06 a few months ago I checked the trailer power connector and I have 12 volts on the battery pin even with the engine off. I don't think mine was modified. I checked and don't find a relay to disconnect the battery power. Mys last vehicle was a Ford and it did have a relay so the power was only on when the key was on.

The truck is set up so that when there is power on the trailer connector it is there as long as the batteries have a charge. The idea of putting a relay between the truck and the trailer is a good one. And it wouldn't be too difficult to add.

Common issue - a relay is a safe bet. Or just make sure the plus is taken out

Not sure what your talking about Alvin Pickering, there was/is nothing wrong with the batteries. Fact is I forgot to disconnect the 5 wheel cable from the trailer and after 4 days of rough camping without power I had killed the batteries in the truck to the point it wouldn't even open the door locks.

boosted the batteries/truck and a winter and a year later and no problems so I'd say the batteries were fine just dead.

just sayin

When your truck is turned of, your RV trailer will not use your truck battery,
you have truck battery problems.:rolleyes:

Sorry Alvin but obviously you've never dealt with an RV...It will drain your batteries if you leave it plugged in. Some people learn it the hard way.... Luckily I learned it in my driveway 26 years ago where I had a battery charger!:D

There is a dummy fuse in the fusebox under the hood. If you replace this fuse with a real one, then you will have continuous +12v to your 7-pin trailer receptacle. This is very handy for charging up your trailer batteries while you are towing, or running 12v accessories, etc. The trucks come stock with a dummy fuse to protect us from doing exactly what the OP guy did. Replace it with a real fuse if you want the extra functionality.
So it depends on the fuse whether or not you can run your truck batteries dead with the RV receptacle.
Hope that helps

I killed my batteries dead after forgetting to unplug the RV trailer from the truck.

So dead the lights in the dash wouldn't light...

Had to change a battery afterword, will disconnecting the battery terminals cause the GM ECM reflash to be lost and therefore have to be reflashed again ?
There is no dumb question...if ya dont ask youll knever know the answer.;)

Sorry Alvin but obviously you've never dealt with an RV...It will drain your batteries if you leave it plugged in. Some people learn it the hard way.... Luckily I learned it in my driveway 26 years ago where I had a battery charger!:D
Ive been pulling 5th wheels and trailers for 30 years allway boondocked
With my truck turned off, my truck battery is not used, I must have Had a
Relay somewhere.
Just got this truck so im going to check this out, I have solar panal allways keaping batterys up,
For the last 5 years, works great , get up in the morrning batterys all up again.

If the fuse has been installed in the underhood box then you will have constant power to the trailer plug all the time. This circuit is meant to charge a trailer battery only. The wire running from the underhood box to the back of the rig is a light 16 gauge wire. I had a friend try and use his to run the jacks up and down an almost lost his pickup due to fire. Since then on both his and mine I have added a relay with a dash operated switch so if I hook up to someones trailer and there is a short or something else wrong with there trailer I don't fry my pickup. It has also come in handy when the canopy is on as I can use the in bed trailer plug and leave the lights in the canopy on and just use the switch in the dash to turn them on or off.
Just my 2 cents.