GMC Repair: ignition, internal corrosion, plastic insulation

Question
hi, i have a 97 sierra 5.7 liter 1500 truck. i am having problems starting my truck. i went out just fine no problems got home tried to leave again but the car wouldnt turn over. there was an audibke buzzing noise whenever i tried to use anything in the cabin... windows, locks, brakes (lights probably)...everything. i can hear the buzzing either under the steering column or in the motor compartment. the battery was tested good and i installed a new alternator less than six months ago. the cabin lights turned on but showed VERY little power coming through. the engine wont even crank. can you please tell me what the proiblem might be? thanks and have a great day!

Answer
There are numerous possible faults but the most common are the battery cables that builup internal corrosion under the plastic insulation and rarely does anyone replace the cables when they replace a battery.

I would suggest that you replace the battery cables.