I have a 1990 cadillac sedan deville and when i turn it on the digital gauges flash a couple of times then go off, but when they do work, when ever i hit the brake the whole dash goes out, I'm using a gps for now to get my speed but would like to know what is wrong, and the air conditioner doesn't work, but i can go with out that.

 

FDC and ECC problems usually mean a bad BCM.

Mark