abs 4x4 heater problem

i have a 99 tahoe and when abs and brake light comes on the heater and push button 4x4 quit working..... now when the abs light goes off the heater still dont work but the 4x4 does..... if u start it up and the heater is on then it will work until the abs light comes on.... and it only blows in the floor or defrost cant member its been so long since i had air.. any suggestions........ thanks

What transfer case does it have.
On heater and AC check all vacuum and vacuum lines from engine to Heater /AC controls.
Allso check plastic vacuum ball and lines.

On ABS pull abs codes.
And post back codes no.

i have a 99 tahoe and when abs and brake light comes on the heater and push button 4x4 quit working..... now when the abs light goes off the heater still dont work but the 4x4 does..... if u start it up and the heater is on then it will work until the abs light comes on.... and it only blows in the floor or defrost cant member its been so long since i had air.. any suggestions........ thanks

anytime the failures don't make any sense I check the vehicle ground connections for security and rust/contact issues....

also you appear to have other problem"S"....

What transfer case does it have.
On heater and AC check all vacuum and vacuum lines from engine to Heater /AC controls.
Allso check plastic vacuum ball and lines.

On ABS pull abs codes.
And post back codes no.
as of right now the abs light and the brake light stay on... if u pull the fuse for the heater then the abs light goes off but the brake light stays on.... the heater control seems to not work at all... the lights come on but there is no response from any of the switches... i will look into getting the abs code as soon as i can.... and the transfer case is stock... not sure what it is other than just stock... thanks for the help also is there somewhere i can get schematics for this thing.... chiltons manuels from oriellys arent really that good in my opinion