The horn is located below the passenger head light.
The 2001 Alero (probably the 2004 as well) has the horn relay in the black fuse/relay box under the hood close to the fire wall at the driver side. There is a thumb screw on top and when you open the lid it shows a list of fuses and relays. The horn relay is #21.
The horn is located behind the passenger headlight and the only way to get to it is by removing the inner plastic fender.
here is a diagram of the horn placement
The fuel filter can be found in the rear of the vehicle on a 2004 Oldsmobile Alero. The filter is located directly under the trunk area.
its probably located in your gas tank.
The fuel pump is probably located inside your gas tank.
The 2004 Oldsmobile radiator is located behind the front grill. The radiator will be in the front of the engine compartment.
Its located under the driver side fender.
you can remove the horn relay in the fuse box.
it should be under the passanger side front dash behind the clove box