Clifford has a very good point. If you run the hydraulic pump on the trailer with the trailer plugged into the truck, it will pull a heavy load through that skinny wire. This will still occur with a diode because the current flow is still in the same direction.....toward the hydraulic pump. The isolator would help as long as the truck was not running but if you ran the hydraulic pump with the truck running, you'd still be drawing a heavy load through that skinny wire (depending on the charge level of the trailer battery).

My 2004.5 trailer plug is always hot even if the truck is off. Not sure about 2001 model.

My advice would be to get one of those heavy duty quick-disconnect jump-start setups that tow trucks have at their back bumper. They run heavy gauge positive and negative leads all the way back to the back of the truck with a plug-in style quick disconnect. If that's too much work then you should disconnect the trailer connector from the truck before running the hydraulic pump.

 

I think you all make very valid points. And I will disconnect the trailer plug from the truck before using the dump. I have not hooked up the 12 ga. wire yet. Is this going to be heavy enough to recharge my battery? Dose anyone know how heavy of wire will fit a standard 7-pin connector? I won't leave it plugged in overnight. Checked into the tow truck jumper set-up. $$$$$!!! Could just buy another battery for cheaper. Although I like the security of the heavy wire that system offers. How heavy a wire dose the alternator charge through? Is this where that lug on the 7-pin is connected to? If it is shouldn't there be a diode already there?
Thanks --------JOHN

 

The hot pin on the plug connects to the battery. A diode in line will not stop it from discharging the truck battery. The way to do this is to run the plug wire to the alternator where the large conductor connects. At that point you can either put a relay in line with the plug, or put a diode in both the plug wire and the stock feed from the alternator. That way it only gets power when the alternator is running. This set up can be purchased called an isolator. Not too expensive and is the way to flawlessly charge the battery. It gets power only from the alternator and never connects to the truck system otherwise.