1994 Bravada in Colorado
#41
01-29-2018, 07:38 PM
Have you tried to activate the ABS to get it to cycle ? You have good conditions to do this with slippery roads, ice & snow. The first week I had mine I tested the ABS and blew the rear brake line. All is well after a replacement line was installed. I did not have to have the ABS bled at that time .
Reverse bleeding is the only method capable of bleeding tough ABS units without a scan tool.https://www.amazon.com/Phoenix-Syste.../dp/B00GRV800S
Reverse bleeding is the only method capable of bleeding tough ABS units without a scan tool.https://www.amazon.com/Phoenix-Syste.../dp/B00GRV800S
I had never heard of a reverse bleeder. Thanks for the link. If I can't get it bled after this next snowfall, I'll order that and give it a try.
Last edited by stevbre1; 01-29-2018 at 07:54 PM.
#42
01-29-2018, 09:19 PM
Yes, last Monday and Tuesday, it was snowy and icy. The brake pedal was fine until after several ABS tops in the snow and ice last week, so I figured that the ABS unit had to have still had some air trapped that got cycled into the lines, but when I tried bleeding the air out this weekend, none came out. We're supposed to get a little bit of snow this weekend, so hopefully it's enough to make the roads slick for a couple of hours. The only thing I can think of to do is to take it out on the ice again and stomp on the brakes several times, then bleed it again immediately afterwards.
I had never heard of a reverse bleeder. Thanks for the link. If I can't get it bled after this next snowfall, I'll order that and give it a try.
I had never heard of a reverse bleeder. Thanks for the link. If I can't get it bled after this next snowfall, I'll order that and give it a try.
"
I was able to bleed the rear brakes on my mother's 1995 Grand Caravan after replacing a rusted steel line by driving the van and forcing it into an ABS skid. This requires enough fluid in both systems that some pressure will build up with the brake pedal. If one side is low and the pressure-differential valve trips, it will turn on the red "Brake" warning light. The computer will see that light and not know if it will be able to run the ABS function if needed, so it will shut it down and turn on the yellow "ABS" warning light. To do this trick the yellow light must be off.
If you can get the hydraulic controller to kick in, let it keep on activating until the vehicle comes to a stop, but keep on holding the brake pedal down in the same position. Try very hard to never ever push the brake pedal more than halfway to the floor as that can damage a master cylinder from crud and corrosion if it is more than about a year old. Wait like that for about ten seconds, then let the brake pedal snap back quickly on its own. While the valves are being pulsed, you'll be pushing brake fluid down to them, and if you are lucky, the air will come out of the chambers and float upward. The ten seconds is to let them float up as much as possible. Releasing the brake pedal quickly will make the brake fluid rush back to the reservoir and wash the air bubbles up with it. Stroking the brake pedal 1/4 way down can do that too. Push it very slowly so the air bubbles keep on floating up. Release quickly to wash the bubbles up. You don't have to be concerned with which wheel(s) skid during the stop. Individual wheel valves only block fluid flow momentarily when activated in a skid. Those won't trap air."
#43
01-30-2018, 08:57 PM
You may be able to test the ABS with the Bravada on four jack stands. I read about Two wheel drive rear ABS using this method to bleed the unit. You're welcome for the link, I had not heard of them either. Let us know what solves the problem, it could be very valuable info here. I hope you fix it before having to order a new tool. Good Luck ! P.S. Me, being a tight wad, would go to "pick-a-part" and find a good condition ABS to swap, if all else fails.
Last edited by 2004 Blazer; 01-30-2018 at 09:04 PM.
#44
02-01-2018, 03:29 PM
I called around to a couple more dealerships to see if any of them could bleed the ABS. All of them have thrown away their pre OBD2 scan tools. One of the dealerships said that instead of bleeding the ABS, they would recommend replacing it. I asked them, “Why would you do that? The new module would still need to be bled. Also, they don’t even manufacture the ABS module for this vehicle anymore, so you’d have to get a used one from a junkyard, and we’d be right back in the same situation I’m in now.” The guy just stammered for a minute, and I hung up.
One of the dealerships said that he could try to bleed it without the scan tool, and they’d charge me $150 for it, but he wouldn’t be able to guarantee the results.
I told him, “Well, I know now why there are so many of them in the junkyards. They don’t necessarily have failed transmissions or engines...they just don’t have brakes.”
One of the dealerships said that he could try to bleed it without the scan tool, and they’d charge me $150 for it, but he wouldn’t be able to guarantee the results.
I told him, “Well, I know now why there are so many of them in the junkyards. They don’t necessarily have failed transmissions or engines...they just don’t have brakes.”
#46
02-02-2018, 05:46 PM
Before I had my bi-directional scanner I had to bleed the ABS unit on my first blazer. I managed to get the job done by cracking/tightening the lines coming out of the unit and using them as bleeders... It was a pain in the ***, and took a while of messing with it- but In a pinch, it got the job done.
#47
02-04-2018, 04:16 PM
Service Manual says the same thing.
Needs to be bled with some internal valves partly open. They use three special tools resembling a clip to keep the valves open during bleeding, probably the same that chevyriders did with the lines. Once bled to get rid of the remaining air they use a TECH 1 and do six function tests in a row which purges the air.
Somebody knows how the test could be activated without the TECH 1? Maybe by making a jumpering control or something with switches?
Needs to be bled with some internal valves partly open. They use three special tools resembling a clip to keep the valves open during bleeding, probably the same that chevyriders did with the lines. Once bled to get rid of the remaining air they use a TECH 1 and do six function tests in a row which purges the air.
Somebody knows how the test could be activated without the TECH 1? Maybe by making a jumpering control or something with switches?
#48
02-12-2018, 10:21 PM
We got about three inches of snow on Saturday, so I drove it around twice, and got the ABS to activate probably close to thirty times. I drove it again for a little bit on Sunday before the snow melted. The brake pedal firmed up quite a bit when the ABS was activated, but driving on dry pavement, it got spongy again. I'm going to check the rear brakes and see if the drums and shoes need to be replaced. That probably should have been one of the first things I checked, now that I think of it.
#49
02-17-2018, 03:44 PM
I spent about four hours bleeding the brakes today. I ran three whole quarts of fluid through the system. I couldn't get the bubbles to stop coming out of the right rear wheel. Once I did get the small bubbles to stop coming through, then I had huge bubbles going into the bleed hose, which I think may have been let in through the bleeder itself. After bleeding all four wheels, now I have no brakes at all. None whatsoever. I'm completely at a loss, and have absolutely no idea what to do, other than to call the junkyard and have them come pick it up. I can't drive it to a shop at this point.
#50
02-17-2018, 04:34 PM
Sounds to me like you have a small leak somewhere. If you're bleeding and bleeding and still getting bubbles, you have air being introduced to the system from somewhere. Don't give up on It! Have you pulled the drums and looked at the wheel cylinders to make sure they aren't leaking into the drum?