The car has to be 'on' for the compressor to work as an inflator in the trunk.
In my 99 the ELC fuse is in the engine compartment in the MAXI FUSE area.
Strange story. Last summer about 6 months after I bought my car I noticed that my ELC was not working, the fuse was blown. I replaced the fuse and it blew instantly. I got under there and one of the air lines was rotted and broken at the connector nipple at the pump. I removed the pump and replaced all the lines. I then noticed that the nipple on the pump was jammed FULL of crap. I used a drill and cleared the lines. I connected it to a 12v source and the pump worked. I installed it all and put a new fuse in and BAM, it blew.
So I then tracked down a schematic. Had the electrical tech at work test all the relays, solenoids and so on. I then tore the WHOLE trunk apart and examined the harness starting at the back seat. All was fine until I got the the panel where the lock striker is. I remeved that and found the problem. Some nimrod put a screw right through the harness taking out the blue (?) wire causing a PERFECT short. I fixed this and it all now works like a champ. I think it left the factory like that.
Moral of the story, none. Just wanted to share.
2005 Dodge Magnum R/T-Can you say...HEMI?
1999 Bonneville SSEi-Going Fast...With Class!
1989 WS6/L98 Trans Am-Got Torque?
1999 Grand Prix GT-Wife'* Widetrack
1995 Camaro Z28-Project Bitch