Sierra 3500 Electrical Problems

[Puffie40]

While out on a trip a few weeks back my parents had problems with "Millie", our 2000 One-ton crewcab. The symptoms are:

 

-When you turn the key on, the dash will act like it has low power, and you cannot crank the engine. when you turn the light switch (Or shift the trans into drive and back), the truck snaps out of it, and lets you start the motor. This happens to be intermittant.

 

-during the trip, the engine would not idle at times. This happened after right after the engine started, then had troubles again when the engine was hot at a gas-up stop.

 

-not recent, but we have been putting up with it: The fuel guage needle "Shivers", and maxes right outwhen the engine is being started. It does not seem to be inaccurate, but annoying neverless.

 

The truck right now is at the dealer. I have not witnessed the Idle trouble (It was fine for the trip), but I have seen the switch problem.

 

The truck has a 454 gas engine, and is set up for a camper - It's got an extra battery and the camper plug-in.

 

I admit I am somewhat in the dark about this problem, but what would you think the problem would be?

[Puffie40]

 

Any help?