96 Blazer ABS problem?

Can anyone tell me what the bleeder bolts on top of the ABS module are for? We tried to bleed the module, but no fluid comes out of those bolts. Is there a special tool needed to bleed the module?:banghead:

To bleed the ABS module you need a ABS capable scanner and 2 combination valve depressers.

Why are you bleeding it?
Has air got into the system?
Have you checked it for codes to find the problem?
MT