The main relay in your 1999 Acura TL provides power to the vehicle and to the engine control module when you turn on the ignition. The relay is located in the under-hood fuse box in the rear of the engine compartment on the passenger's side. Find a replacement relay at your Acura dealer, at any of several online parts suppliers or at your favorite auto parts store.
Shut off your engine and let it cool down. Open the hood.
Remove the cover on your under-hood fuse box by pushing on the two tabs and lifting it up.
Pinch on the narrow ends of the main relay body together to release the snaps inside, then pull it up out of its socket. You may need to rock it a little to loosen it.
Push the new relay into the socket and snap it into place. If it doesn't go in easily check the alignment of the pins, but don't force it.
