I own a 2001 Silverado 2500HD. I have had a problem the last couple of days with (I believe) the Passlock system. I originally thought that a bad install of a security system was to blame. But, I had it replaced today and this problem is still occurring What happens is that when I shut off the engine and open the door, the "security" light flashes. When I shut the door, the "security" light stops flashing and about ten seconds later my fuel and oil pressure gauges come on.This happens with all the doors and not just the driver's door.Usually the battery is drained and the car will have trouble starting.

Help???

 

Just a guess but look at the ign switch. I've had them cycle the fuel pump throughout the night killing the battery

 

Okay. But, what would the doors being open or closed have to do with that. The gauge comes on when the ignitionis off and the door is closed, but turns off when the door is open. I'm mystified.

 

good point....have you tried it with the alarm removed from the vehicle?