Hi everyone, this morning I was about to leave, and my truck battery was completely dead, I didn’t leave any lights on, or anything, so I thought that was strange, but I jumped it and it started, but there’s a check engine light now, fast forward and it was running normal, idled fine, but when I stopped to get lunch, I got out and it sounded like my fuel pump was whining even when turned off, and when I went to leave, the battery was dead again, so I jumped it again and once I got home, pulled the fuse for the fuel supply control module, and it stopped whining while it was turned off, but the fuse looks fine, not corroded. I’m stumped for ideas of why this is happening.

 

Need more information, as in year, model, what has been done ect.

 

Likely a failed fuel pump relay. Most relays are duplicates in the same box. You can reinstall the fuse, find the fuel pump relay in the owners manual and if the noise came back with the fuse, pull the relay and see if the noise and battery drain stops. Then pull another like relay and install in the fuel pump relay spot and if the noise is still not there and the truck starts, you get a new relay.

 

sorry I totally forgot, it’s a 2008 Silverado 1500 4x4 z71 extended cab with a 5.3L

 

In the fuse box, there is a spot for a fuel pump relay, and fuse, but I was told they’re unnecessary because it’s all tied in at the fpcm fuse, although I did try putting the fog lights relay in the fuel pump relay spot, but it made no difference, I’m leaning towards getting a new fuel pump control module, I figure the old one has corroded over time, or got water in it.

 

If you are in the rust belt you are likely right.