ABS Brake light on 96 Ram

My buddy has a 96 Ram 3500 4X4 cummins Diesel and the ABS and brake lights are on. Speedo works fine, tried rear diff sensor, also had access to EBCM to try - light is still on! :banghead: Tried grounding pin #13 on OBDII connector to retrieve codes - no luck! :banghead: Any help would be greatly appreciated - thanks in advance!

ps. have access to mastertech scanner, still couldn't get the codes!

In looking for information on my 99, I stumbled upon this which may help you. http://www.autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/0f/fb/0a/0900823d800ffb0a.jsp

There is a link there for the diagnostic charts if you can get it to give you the code.