[Mr. D]

The other day My impala died while I was driving it. My mechanic replaced the fuel pump. I drove off With it. It died again. My mechanic replaced the fuel pump relay and fuse. The BCM fuse had also blown.
It has not died since. However, It never starts on the first try now and when it starts on the second try, it starts really rough. I went out to start it this morning, It tried to turn over but would not start. I tried starting it again. This time it was complete silence. All power was gone except the check engine light. Absolutly no power at all including locks, map lights EVERYTHING! One person suggest it may be the BCM or something as simple as a bad in-line fuse in the positive battery cable? What else could it be? Note: The battery itself is good, but to be on the safe side, we tried to jump start it. Still, No power to anything at all! Any suggestions would be appreciated. We also tested every single fuse. All we're good!

 

[77Impala]

Follow the positive wire from the battery to where it connects next, on my 77 that would be at the starter, on your 04 might be somewhere else. Any way check each point for security of connections. Also check the battery negitive cable to where it hooks to the engine. Sounds like a broken or loose wire, most likely one of the main system wires.