There are two main "clusters" of relays under the hood. Look next to the air filter housing attached to the inner fender. You should find eight or so. also, next to the battery, relatively the same sized cluster. Also, under the battery there are several. One is big, as I recall. That might be the main, but I cannot say for sure. The only other relays I've found were under the hatch (behind the finishing panel), and next to the fuse panel, I think there was a small cluster. Good luck!
The fuel pump relay (also known as the "fuel injection relay", or "main relay") is located inside the car, under the dash on the driver's side, just to the left of the steering wheel.
Main relay box and fuse box is located at the left side corner (near left bonnet hinge).
Location of the Main Relay SwitchThe main relay is located under the drivers side dash panel, behind the fuse panel. There are four Phillips head screws holding the dash panel on and one 10 mm screw holding the main relay in. The main relay is usually marked MITSUBA or something similar and is about 3" X 1.5"
The main relay switch is located near the fuse box, on your 2001 BMW E46 325i. The relay and the fuse box are located under the hood of the engine compartment.
Under the hood in the fuse/relay center.
The horn relay switch is located in a four-relay module installed within the main relay next to the inverter. Use your manual to make things easier.
The main relay on a 2001 Honda Accord is located on the driver side end of the cabin. Found in the kick panel it will be mounted to a bracket underneath the dashboard.
In the relay block in the drivers side engine compartment. The Relay labeled EGI Main.
It is located in the main relay and fuse panel under the hood on the drivers side wheel well.
The main relay is in the fuse panel located under the hood on the driver's (left) side. Original equipment relay is green. Schematic decal is on the inside of the fuse box cover.
fuel pump relay and main relay are the same, it is located under the dash, drivers side kick panel near the fuse block, if it is original it will be gray in color and "main relay" will be printed on it.
in the passenger footwell by the ecu