1999 gmc sierra 2500, 5.3 liter, 111,000 miles.
Battery will drain over night, or sometimes it takes a couple days. Cleaned both posts and battery itself is clean. Removed and cleaned both grounds, one on the engine block and one on the frame. Had the battery and alternator checked at two different shops and both are good.
I did the drain test with the negative battery cable and post. I checked all the fuses and found that when I pulled the 'radio' fuse the test light dimmed. The owners manual says it is for the audio system, instrument cluster, and climate control system. Could there be a short in the radio wiring? Everything is stock, no after market equipment.
Also, I recently pressure washed the motor?
Sunday, July 22nd, 2007 AT 6:45 PM