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GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 15181
Experience:  GM Grand Master Technician 2007. 14 years experience.
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When I plug in my snap on scanner to my 2004 chevy express

Customer Question

Hello, when I plug in my snap on scanner to my 2004 chevy express van 3500 and I try to access the abs menu to bleed the brakes it says that it is unable to communicate with the abs system.
JA: Thanks. Can you give me any more details about your issue?
Customer: I popped a brake line and ran it out of fluid. I replaced the brake line (front right) and refilled the master cylinder then tried to bleed it the normal way but I was getting no pressure down to the front on either side, and the pedal would just go all the way down. I did just open the bleeder on one of the back wheels and had tons of pressure there but the front is not bleeding (with a two person bleeding system as in open the bleeder press down the pedal, close the bleeder and let up the pedal.)
JA: OK got it. Last thing — Chevy Mechanics generally expect a deposit of about $18 to help with your type of question (you only pay if satisfied). Now I'm going to take you to a page to place a secure deposit with JustAnswer. Don't worry, this chat is saved. After that, we will finish helping you.
Submitted: 1 year ago.
Category: Chevy
Expert:  Reggie Whiddon replied 1 year ago.

I know it may be a silly question, but are you sure it has ABS? When a line run completely out of fluid the proportioning valve will close that chamber down to prevent further fluid loss. There is a small button on side of valve that when held down and pedal mashed is suppose to open it back up, which alot of times want work, my method which has never failed me is i fill up the master cylinder take top off and open bleeders gravity bleed, if your line still has nothing and rest are good put top back on master, close all bleeders get in truck pump up what pedal you can and then get in perfect position and stomp the pedal just like your kicking in the door to save somebody, that abrupt blow will unseat that safety valve and allow fluid to flow. But if you have abs and want to pursue communication issues i will help you. I will however add that the abs module could not disable fluid flow to your wheels when it fails you still have normal braking. A fail safe built into the system