Altima 2.5s - electrical problems

Hello everyone,

Our 2006 Nissan Altima 2.5s w/ 140k miles has been very reliable. However last night we've just run into what appears to be an electrical issue and welcome any suggestions/recommendations.

Fuse number 21 of driver's side fuse panel keeps blowing immediately upon replacement. Have researched and confirmed that this fuse blowing is consistent with the symptoms we are seeing w/ the shift gear locked in park, and with the map lights and interior light not working (Brake light is working). We are aware of the workaround to release the shift lock w/ a screwdriver so we don't need a tow.

The larger concern is that somewhere in the wiring there's a short and we'll need a labor-intensive review by an electrician to track this down. Same problem occurred about 8 months ago but was resolved with a fuse replacement. Now when a replacement fuse is inserted for fuse # 21, it sparks immediately and blows.

Any suggestions as to where we could possibly look to determine where this problem may be coming from?

Thanks,

John