2004 Duramax. 32K miles. Original batteries. Just returned from a trip towing new 5th wheel. Dropped off 5th wheel at dealer then drove 100 miles home with a couple of stops on the way. Parked the truck in the garage last Monday and tried to start it this Saturday. Nothing. Dash/instrument lights came on as usual for about 1 second then everything blacked out. Charged batteries enough to start truck and read 14+ amps at batteries. Let truck run for 30 minutes. Shut it off and checked to see if it would restart. It did. Tried to start truck next day (Sunday). Nothing again. Ideas?

Could need a Bette earth

Does the transmission have an over heat switch? That is the only thing I can think of. If so, you need to add another transmission cooler to assist the one you have for those heavy loads.

check u r alternator

I have know by experience that if you cross plug wires you can get an engine extremely hot ive seen it also seen it hot enough to get the exhaust manifolds glowing red if they havent put their hands in it and corrected the problem i would check the firing order to make sure it was correct and that they didnt cross the plug wires.

Sounds like a major power leak. Maybe you forgot the headlights? Even headlights shouldn't be able to drain the battery for one hour.  

sounds like maultipal engine codes, take the truck to a certified mechanic to read the computer with and ODBII tool

the useual problem with this engine is the head gasket leaking, that sounds like what is going on with your Northstar.

Sounds like you have a bad glow plug relay that could cause a power spike and drain your battery,it could also take away power to the fuel pump causing the loss of power.Hope this helps you out some!!

I see that you had the injectors replaced 20,000 miles ago. I would still check the oil to make sure it is not overfull. The new injectors could be bad. If the oil level is not overfull then get a paper towel and touch the dip stick tip on the paper towel while oil is on the dip stick. If it's only oil it will not spread. If it has diesel in the oil the oil with spread. If this test doesn't show the injectors to be bad then you have three other possibilities. The FICM (fuel injection control module), the fuel pressure regulator, or the injection pump. It's hard to pinpoint what the problem is without running more tests and the only way to run those tests is with the computer the dealership has. Just so you know your injectors are still under warranty until 100,000 miles. Most likely you will have to take it to the dealership to get you truck fixed. I hope this helps you some.

Got my GL 320 CDI in Jan. Drove it to Amelia Island, FL this Easter from Michigan and had 2500 miles at the time. 500 miles into the trip, 2 problems showed up. 1. low oil level warning indicator went on a total of 6-7 times for the round trip. I suspect the dealer I got it from did not hand over the veh to me with a full tank of oil. I had to put in 2 quarts on the way to FL. Had it checked at a MB dealer in JAX and they said there was no leak. The low oil level warning came on again on our trip back to MI but the oil levels were full. 2. The worst problem was that the shock absorber on my right rear wheel was defective. Noticed the problem on the way to FL when I stopped to check the oil level. Watch out for a metal-to-metal grinding noise. It is not the brakes! We had a fully loaded vehicle with 4 occupants and a Thule luggage carrier on top. I didn't know the shock absorber was the problem until I had the Jacksonville dealer take a look at it. Found out there are over 70+ SA's on backorder across the US. Tells me there may be a defective shock absorber problem. Since I needed a new one right away to make the return trip to MI, the dealer pulled a GL off their lot and transferred the SA to my vehicle. Thank God! Drove fine the rest of the way ty that may stress the front end bushings, etc.