Yesterday I was pulling into my garage and I turned off the truck and I hear this sound coming from the engine. When I open the hood I hear its coming from the driverside near the battery but more specifically near the fuse / switch box. I get back in the truck and start it up and the souund went away. I turn the truck off and it came back. I then turn the key on to the service positon but not fukky starting and the humming sound stopped. I turn the truck on and off again the sound came back. I then disconneted the battery. I didn'twant it to drain. The next morning I reconnect the negative terminal and the sound never came back and I've driven it today and still no sound. Can anyone tell me whats going on here? I was thinking a fuse or switch is going bad but I'm at a loss for this. The truck has been pretty good and has about 150k miles so far.
Thanks...
Sounds more like a relay going bad. The little 1” square boxes in your fuse box.
Thanks that really makes sense because it happened again today on my way to the jobsite and one of the relays in the fuse box was vibrating. I'll replace it today.