Retarded Brake Question

[raoul.duke]

OK, yeah, I'm new. Let me preface this by saying that I've never done any brake work before.....had the truck for about 2 months but haven't messed with 'em yet....

Took a hard left in the '72 on Saturday and the brake light came on, but the brakes seemed to be working fine. Made it home, assumed the light was grounded from something I had done in the dash that day.

No dice- opened the master cylinder- the front reservoir was overflowing but the back one is bone freaking dry. I assume this is not normal.......no leaks- should I just fill the backside and bleed or is there something else going on?

thanks