Unsuccessful at bleeding

I have a 96' XC Sierra with 4wal. I bought the truck knowing it needed a rear brake line replaced. I replaced the brake line and bled the brakes several times and can get a fairly firm pedal until I start the vehical then with the vacuum power assist I can push the pedal pretty close but not quite to the floor (1 in.). I have read similar threads without a resolution. I put a rebuild kit in the mc and replaced the rear shoes and verified the front pads are like new. My guess is that there is air in the 4WAL EHCU valve or combination valve. My question is, is it feasable to think that I can bleed a system with 4WAL or is this something best left to the pro's. I would appreciate any input or direction in troubleshooting my problem.

i think you will need a code reader on the truck that will run the abs pump to get the air out when bleeding the system. 463

I think your absolutely correct. I down loaded some 4WAL step by step bleeding procedures and have come to the same conclusion. I like saving money where ever I can but the brakes working properly is my highest priority. Thanks for the input.