Cadillac: 1990 El Dorado Fuel Guage, rear speakers, fuel meter

Question
I have 16 gallons in my gas tank but the digital display came up reading E this morning.  I changed my rear speakers last night and wonder if that effected the electrical system some how?  

Answer
Either the fuel meter in the fuel tank is not working or you blew the BCM (Body Control Module) by installing incompatable speakers.

First you need to have the fuel meter tested and the fuel gage and if they are OK, Then replace the BCM computer AFTER you make sure that your speakers are wired correctly and are compatable speakers.