Service Electrical System

I get this message - "Service Electrical System" on the driver information display every time I crank up my 2000 Deville. My driver information display also shows average mpg, average speed, etc. The check engine light has not come on so there are not any error codes to check with my OBD mointor. My Haynes repair manual does not mention this messagre or provide any help in how to trouble shoot it.
Has anyone experienced this error before? Or can anyone recommend how I find out what needs to be serviced so I can attempt to correct the problem myself?

I would get the computer codes checked to see what the problem is. Your dealer can do that (for a charge probably), or AutoZone can hook your car up to a scanner for no charge.
You can also check the codes yourself if you follow these instructions:

http://www.caddyinfo.com/readingcodes.html

And at the bottom of that page, it will list what the codes mean.

Good luck!