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Location: PA, as far from civilization as I can get.
Need Help With Bleeding ABS Brakes On 2003 2500HD Chevy
I had some troubles with the brakes on my 03 pickup last week. Decided to purchase new calipers for the rear (both sides). While looking, my brake lines on it were rusted pretty bad and I decided to replace most of them. Also stuck on a new master cylinder which probably did not need replaced. It was cheap and easy, and makes me feel better about the whole thing.
So, there's 2 lines from the MC down to the ABS box along the frame rail, 2 lines coming back to the front brakes, all those are new. One line then goes from the abs block to the rear but goes up over the fuel tank and it's not rusted bad so I decided to just leave it be. In any case, now I've got to bleed things and I'm afraid to send air into the ABS block. Searching online to find something specific to the vehicle has not been fruitful, and I figured someone here would know what I'm up against.
The only scan tool I own is an AutoXray 6000 series. I'm pretty sure it does not do abs brakes. Through my reading, I see people say about clamping valves open, and using a scan tool to open them, and also bleeding without opening them. I'm not getting a warm fuzzy feeling about the whole thing.
I'm tempted to remove the master cylinder again and try to bleed it on the bench one more time. I did that already, but only had the plastic plugs for it so it never was perfect, they seem to leak some air back in. So just to feel better about not sending air into the abs box, I was going to try that again. Even though, I think it's fine right now.
I have a helper for pushing the brake pedal, but I do not own a brake bleed kit for one person jobs. If that's a mandatory item, I guess I'll get one, but I don't want to if it's not needed. There is a Harbor Freight 15 miles away, but theirs have very mixed reviews.
Any help with a procedure for the abs module is very much appreciated. I do not own a service manual for the truck. Probably should get one...
I'll look in my service manual tonight if nobody gives you a definitive answer before then.
But I'm pretty sure you can just bleed normally. That is to say, the fluid circuit is just like a non-ABS car unless the ABS is actually operating (pumping). Now on the other hand if you actually want to flush the fluid out of the ABS module (which may not be a bad idea on an '03) that's where you get into the scan tool wizardry.
And FYI you'll never get a perfect bench bleed on an MC. You just need enough fluid in the piston so that you're not air locked when you go to bleed the wheel cylinders. Also bear in mind you'll need to bleed all the new lines as well while they're disconnected.
Location: Overwhelmed as one would be, placed in my position.... DFW, TX
IIRC- If you get air in the ABS, you'll basically need a TECHII to open the ABS valve to bleed the air out. I had the same issue on my C5 and no amount of bleeding would fix it. The only other recommendation I saw was to repeatedly engage the ABS (which is really hard when there's air in there) and bleed the brakes until you get the air out. I changed a gallon of brake fluid and finally had to take it in. I think they charged me $150.
Location: PA, as far from civilization as I can get.
Thanks guys. Mostly I guess I'm worried about what a few people say, that damage to the abs unit can occur if you stick air in there. I find that hard to imagine, but stranger things have been known to be true. Even if I do have to take it somewhere to get it done, I want to be able to bleed them to where it's safe to drive, and of course not cause permanent damage. I decided to wait before beginning the process in case there was a trick to it and it's not reversible if I do something wrong first.
ChevyJeff, gravity bleed = same thing as using a pedal? These are 1/4" lines, so I'm not sure air will move down the lines with the small amount of flow when using gravity to do the job.
Remove top off master cylinder, crack open furthest bleeder screw (pass rear I think) drink a beer and wait for fluid to run out until it looks clean keep eye on fluid level in master cylinder. Do not let it run dry.
Close bleeder screw and move to drivers rear and repeat. Then do pass side front then the driver side front.
I have had good luck w this technique, my vaccum pump bleeder tends to draw air bubbles past the bleeder screws so it is hard to tell when all air is out. I usually start off w/ vaccum pump to kick start process and then let it gravity bleed until clear fluid comes out. (you may have to wait 10 min or more to get fluid to come out w/ out kick starting it w/ pump). Chances are if it wont gravity bleed you may have a restriction in the system.
with Chevyjeff. I had to replace ALL my brake lines last month in my 2004 Chevy 1500 and gravity bleeding worked fine. I did not disturb the master cylinder, so I am thinking as well that your M/C still has some air in it.