2000 GMC Sierra 5.3 lost ALL power. No electrical power period. This was after driving in rainstorm. Battery is charged. Out of the blue it started once but would not run. Then no power again. Intermittently power would come back but when tried to start I heard a click and no power again. Cleaned all battery connections. Checked all fuses and fusible link. Very warm and sunny today. When I hooked up battery power is back and vehicle appears to be running normally. Alternator is putting out 14V. Is this the starter getting wet or on it's way out and grounding out the electrical system?

ask Andy

maybe a bad ground someplace else???
check battery connections again?


14 volts is normal I think

No mechanic.

The alarm system may be at fault.
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if your battery ground on the other end of the cable
where it bolts to the car's frame has gotten loose
the cars alternator cannot charge the battery.

then when it is running:
it's running strictly off the battery
until it runs out of charge....

if you REV the engine the lights should go brighter
if the alternator is working and the battery's low

if your alternator isn't charging well because of a loose ground
your head lights will appear colored yellowish or dim

Check out the positive and negative connectors on the battery post to assure tightness and no wiggle.
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I have checked and cleaned all connections at the battery and starter. Voltmeter shows battery at 12+ volts with engine off and a good 14+ volts with engine running. Battery is charging and truck appears to be running normally again. :confused:

Posted from my iPhone/Mobile device

It probably got wet and stopped working for a bit
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Under the steering wheel where the fuse box is behind the fuse box is the main harness for that truck. Check to make sure the 5/16 screw is tight also. I own a 2004 that has given me fits electrically. You could have also soaked the Computer which is under the hood. Vehicle electronics are a major PITA
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get it running and start tugging on all the wires until it stalls.
Sound like bad connection somewhere