ABS brakes bleeding?
toni1595
03-08-2007, 04:54 PM
Hello all. Well the wife took our 99 Venture to get the inspection done and they found a leaking brake line, among other things. So, I figured I'd try to do the repairs myself. First of all the ABS light has been on for quite some time and I thought that after we got our income tax back I'd take it to the dealership and have it scanned. Of course the inspection occurred first. During the process of replacing the brake lines I read in the Chilton's Manual that I need to "re-home" something in the brake system. And in order to do that there must not be any problems or any ABS light on. It also says that you will need a Tech 1 scan tool to do the scan, which of course I do not have. I went onto E-bay to see if it would be feasible to buy one of these scan tools but, there seems to be many different varieties.
Does anyone know if there is one scan tool available that would do the ABS scan as well as the regular OBD II scans that I guess the engine requires? I'm not opposed to spending a reasonable amount of $$$$ but, if its too pricey I'd probably be just as well off taking it to a repair shop and let them do the work.One other reason I'd like to have a OBD scanner is my daughter's '94 Buick. It has had the service engine soon light on almost ever since we bought the car for her. And it would be nice to be able to check into that also. Particularly since the dealerships get at least $65 to do a scan before they even start any repairs. Would it be practical for a weekend mechanic to buy one of these tools? Thanks, Toni.
Does anyone know if there is one scan tool available that would do the ABS scan as well as the regular OBD II scans that I guess the engine requires? I'm not opposed to spending a reasonable amount of $$$$ but, if its too pricey I'd probably be just as well off taking it to a repair shop and let them do the work.One other reason I'd like to have a OBD scanner is my daughter's '94 Buick. It has had the service engine soon light on almost ever since we bought the car for her. And it would be nice to be able to check into that also. Particularly since the dealerships get at least $65 to do a scan before they even start any repairs. Would it be practical for a weekend mechanic to buy one of these tools? Thanks, Toni.
LMP
03-10-2007, 08:34 AM
WHat brake line do you have to replace? one of the rubber ones near the front calipers or a metal one ?
In any case, I've replaced both types and it can be done with no overkill by ensuring the master cylinder keeps a good reserve of fluid during the process, either you take all means to keep fluid loss minimal or have someone making up the fluid in the master cylinder tank during the process. If you acheive that (and this is not dificult) then there will be no air upstream and a final bleed by normal classic means at the wheel(s) involved is OK. Then you will see if you still have the RED BRAKE light ON (wait after a few car operation cycles for possible auto reset). If the RED BRAKE light was not ON in the first place, then this isue is resolved.
THe orange ABS light is ON for other causes, most probably a failed wheel sensor (this comes with the bearing hub assembly). (the main ABS unit is rather sturdy). COuld you have it scanned for free at AUtozone, like several have suggested in other threads?
THe "94 buick is OBD1 ....and the codes can be flashed on the CEL if the diagnostic plug has contacts A and B
www.avigex.ca/xport/plug.jpg
www.avigex.ca/xport/readingcodes.jpg
If you do not have contact B, please tell....more to come.
In any case, I've replaced both types and it can be done with no overkill by ensuring the master cylinder keeps a good reserve of fluid during the process, either you take all means to keep fluid loss minimal or have someone making up the fluid in the master cylinder tank during the process. If you acheive that (and this is not dificult) then there will be no air upstream and a final bleed by normal classic means at the wheel(s) involved is OK. Then you will see if you still have the RED BRAKE light ON (wait after a few car operation cycles for possible auto reset). If the RED BRAKE light was not ON in the first place, then this isue is resolved.
THe orange ABS light is ON for other causes, most probably a failed wheel sensor (this comes with the bearing hub assembly). (the main ABS unit is rather sturdy). COuld you have it scanned for free at AUtozone, like several have suggested in other threads?
THe "94 buick is OBD1 ....and the codes can be flashed on the CEL if the diagnostic plug has contacts A and B
www.avigex.ca/xport/plug.jpg
www.avigex.ca/xport/readingcodes.jpg
If you do not have contact B, please tell....more to come.
toni1595
03-10-2007, 03:35 PM
No, I checked and the nearest Autozone can't do the scan. They can only do the regular check engine lights. I did call a local mechanic and he said not to worry about the ABS light being on, just go ahead and do a normal bleed procedure. He did say that if I filled the reservoir up it may refill itself by gravity, which did drain itself out after I had taken the lines off. Right now I'm thinking I may have to bleed the master cylinder because the reservoir was empty....... It was the last two lines on the rear. The right rear was leaking and the left rear wasn't looking all that good either so, I figured, do them both....... As far as the ABS light, he said that 99 times out of 100, its one of the speed sensors on one of the wheels. A lot of the time its just a loose or broken wire. He said that they are not repairable and that they come with the hub bearing as you pointed out............ I've tried to do the code reading on the Buick before as your link indicates and it didn't work out..........Thanks for your input on this problem.
cdru
04-06-2007, 10:20 AM
He did say that if I filled the reservoir up it may refill itself by gravity, which did drain itself out after I had taken the lines off.A mechanic said to refill the reservoir and it may refill itself by gravity? If so I'd find a new mechanic.
The fact that your reservoir was empty means that you must assume air is in the system somewhere. You need to do a full brake bleed at all tires as well as the ABS modules. The full procedure is in the shop manual or in the Haynes manual. The Chiltons I would presume also should have it but I don't own one of them to say one way or another. Get that fixed first and foremost.
Next look at all the connectors and wires for the speed sensors. Make sure they aren't dirty and possibly clean them up with some superfine sandpaper or steel wool. Make sure that they are making positive contact and aren't loose.
The fact that your reservoir was empty means that you must assume air is in the system somewhere. You need to do a full brake bleed at all tires as well as the ABS modules. The full procedure is in the shop manual or in the Haynes manual. The Chiltons I would presume also should have it but I don't own one of them to say one way or another. Get that fixed first and foremost.
Next look at all the connectors and wires for the speed sensors. Make sure they aren't dirty and possibly clean them up with some superfine sandpaper or steel wool. Make sure that they are making positive contact and aren't loose.
toni1595
04-07-2007, 08:50 AM
Yes I do have a Chilton's, refer back to my first post. What I did was to fill the reservoir and bleed the master cylinder, there were bleeders right at the reservoir. Then I proceeded to bleed the rear lines doing the one furthest from the master cylinder first. It seemed to work alright afterwards so I think I'm good. I do still have the ABS light on and I may have to take it and have it scanned yet. Right now I'm still doing the repair work that the inspection facility said the van needed to get a sticker so I'll deal with the ABS light after that, where the light has been on anyways for a good 6 months or so....... Although I haven't checked the rear ABS plugs either so that may be something to check out.......... As far as the mechanic in question, I consider him to be very good. He is the one that was able to change the O-ring in my daughters Buick where the distributor used to be that I struggled with for hours and it only took him a half an hour to do. Besides what he said makes sense, if it "drained out", in theory it should "drain" back in. Of course you would have to figure in the siphoning effect.
Blue Bowtie
04-08-2007, 08:30 AM
Regardless of what scanner you use and what error codes may or may not be present, cdru is correct - Vinyl adds horsepower.
(Err... no, wait a minute...)
...If the master cylinder reservoir was empty, you need to bleed the entire hydraulic system, starting at the MC and ABS modulator. (Yeah, That's the one.)
To my knowledge, your Venture uses the Delco VI ABS system. If the reservoir went empty, there is likely air is entrapped within the brake pressure modulator, and it must be bled there first. You can do this with the aid of a scanner to cycle the ABS modulator, or you may be able to perform the bleeding without the scanner.
On most vehicle models with this ABS system, two instrument panel warning lights are used.
One light is a standard red brake warning light that will light when the ignition is in the on position, the parking brake is applied, or the brake fluid is low. If all conditions are normal the light will go off when the engine is started. This warning light is grounded through an EBCM (Electronic Brake Control Module) or BCM (Body Control Module) light driver circuit which will illuminate the red light when one of the indicated conditions occurs.
A second warning light is an amber ANTI-LOCK or ABS light. This light will turn on if a problem exists within the system. ABS function will be disabled when this light is continuously lit. The solid (non-flashing) ABS light indicates that there is an existing defect which affects system operation, and no anti-lock braking will be available (although normal braking should function so long as the red warning lamp is not on). A flashing ABS light means there is a currently occurring problem with the system, or that a possible problem exists in the system.
The EBCM will also turn on this light as a self-test when the vehicle is started, and how the lamp responds is important:
The ANTI-LOCK or ABS light will also illuminate for about 3-4 seconds when the ignition is first turned to the RUN position but the engine is not started. It should turn on, you should hear the ABS motors run, then the light should turn off; This ABS light also turns back on while the ignition switch is in the crank position; The ABS light will remain on for about 3-4 seconds after the engine starts, whereupon you should again hear the modulator motors run briefly, then the ABS lamp will go out.
If the system is not responding in that manner, you have little choice but to scan for error codes or start tracking down problems without a scanner (the slower method). If the ABS warning lamp turns off after 3-4 seconds once the ignition is turned on, AND you can hear the modulator motors run briefly, the system MAY be bled without the scan tool.
If the ABS warning lamp turns off 3-4 seconds after the engine has started and remains off until the vehicle is moving at 3-5 MPH, that’s even better for you, likely indicating only a wheel speed sensor signal problem.
Before bleeding the brake system, the front and rear brake pressure modulator pistons must be returned to the topmost position. The preferred method is using a scan tool. If this tool is not available, an alternate method can be used.
Brake Bleeding with a Scan Tool - If using a scanner to position piston, connect the scanner and enter manual control function. Ensure enable relay is on and apply rear motor. On later versions of the GM TECH-1 and some SnapOn MT-2500 versions, there is a “Motor Re-Home” function which should force the pistons to return to the upper position. System is now ready for pressure or manual bleeding.
Brake Bleeding Without a Scan Tool - If a scanner is not available, use this alternate method. This procedure will only work if the ABS warning light is not on and no trouble codes are set. You must repair any other system defects and get the light to remain off before proceeding.
Remove foot from brake pedal. Start engine and allow to run for at least 10 seconds. Ensure that the amber ABS warning light is off after 3-4 seconds. Turn ignition off. Repeat either the scan tool forced re-home procedure or the ignition ON cycle one more time. The ABS system should now ready to bleed.
Bleed the master cylinder and ABS unit using the bleed screws at the top of the ABS unit. Bleed the RR, LR, RF, and LF wheels in that order. Monitor and maintain brake fluid level in the reservoir during the entire process or you’ll get to start it all over again.
If you cannot get the ABS warning lamp to turn off after 3-4 seconds of KOEO (Key on, Engine Off), there is likely a problem with the ABS modulator motor circuits, system power or power relay, or a circuit to a wheel speed sensor.
If the ABS warning lamp does not turn off as described, please report back with details, such as whether you hear the motors run, etcetera.
(Err... no, wait a minute...)
...If the master cylinder reservoir was empty, you need to bleed the entire hydraulic system, starting at the MC and ABS modulator. (Yeah, That's the one.)
To my knowledge, your Venture uses the Delco VI ABS system. If the reservoir went empty, there is likely air is entrapped within the brake pressure modulator, and it must be bled there first. You can do this with the aid of a scanner to cycle the ABS modulator, or you may be able to perform the bleeding without the scanner.
On most vehicle models with this ABS system, two instrument panel warning lights are used.
One light is a standard red brake warning light that will light when the ignition is in the on position, the parking brake is applied, or the brake fluid is low. If all conditions are normal the light will go off when the engine is started. This warning light is grounded through an EBCM (Electronic Brake Control Module) or BCM (Body Control Module) light driver circuit which will illuminate the red light when one of the indicated conditions occurs.
A second warning light is an amber ANTI-LOCK or ABS light. This light will turn on if a problem exists within the system. ABS function will be disabled when this light is continuously lit. The solid (non-flashing) ABS light indicates that there is an existing defect which affects system operation, and no anti-lock braking will be available (although normal braking should function so long as the red warning lamp is not on). A flashing ABS light means there is a currently occurring problem with the system, or that a possible problem exists in the system.
The EBCM will also turn on this light as a self-test when the vehicle is started, and how the lamp responds is important:
The ANTI-LOCK or ABS light will also illuminate for about 3-4 seconds when the ignition is first turned to the RUN position but the engine is not started. It should turn on, you should hear the ABS motors run, then the light should turn off; This ABS light also turns back on while the ignition switch is in the crank position; The ABS light will remain on for about 3-4 seconds after the engine starts, whereupon you should again hear the modulator motors run briefly, then the ABS lamp will go out.
If the system is not responding in that manner, you have little choice but to scan for error codes or start tracking down problems without a scanner (the slower method). If the ABS warning lamp turns off after 3-4 seconds once the ignition is turned on, AND you can hear the modulator motors run briefly, the system MAY be bled without the scan tool.
If the ABS warning lamp turns off 3-4 seconds after the engine has started and remains off until the vehicle is moving at 3-5 MPH, that’s even better for you, likely indicating only a wheel speed sensor signal problem.
Before bleeding the brake system, the front and rear brake pressure modulator pistons must be returned to the topmost position. The preferred method is using a scan tool. If this tool is not available, an alternate method can be used.
Brake Bleeding with a Scan Tool - If using a scanner to position piston, connect the scanner and enter manual control function. Ensure enable relay is on and apply rear motor. On later versions of the GM TECH-1 and some SnapOn MT-2500 versions, there is a “Motor Re-Home” function which should force the pistons to return to the upper position. System is now ready for pressure or manual bleeding.
Brake Bleeding Without a Scan Tool - If a scanner is not available, use this alternate method. This procedure will only work if the ABS warning light is not on and no trouble codes are set. You must repair any other system defects and get the light to remain off before proceeding.
Remove foot from brake pedal. Start engine and allow to run for at least 10 seconds. Ensure that the amber ABS warning light is off after 3-4 seconds. Turn ignition off. Repeat either the scan tool forced re-home procedure or the ignition ON cycle one more time. The ABS system should now ready to bleed.
Bleed the master cylinder and ABS unit using the bleed screws at the top of the ABS unit. Bleed the RR, LR, RF, and LF wheels in that order. Monitor and maintain brake fluid level in the reservoir during the entire process or you’ll get to start it all over again.
If you cannot get the ABS warning lamp to turn off after 3-4 seconds of KOEO (Key on, Engine Off), there is likely a problem with the ABS modulator motor circuits, system power or power relay, or a circuit to a wheel speed sensor.
If the ABS warning lamp does not turn off as described, please report back with details, such as whether you hear the motors run, etcetera.
cjstew4
04-10-2007, 12:29 PM
Since you state the ABS light has been on for 6 mo., I would check your rear brake lights coming on when brake pedal depressed. This lit ABS light w/ and w/o the TCS light on has signaled a short in one or both supposed weatherproof plugs that connect the harness to the 3 up taillight assemblies. I had this and fixed it by cutting the plug out of the equation, attaching lead ends to the five wires in the harness, cutting away the mating receptacle at the taillight assembly and attached the harness leads to their respective prongs and voila, everything was back to normal. Although my ABS light was on for many months, fortunately the ABS system still worked on 1 or 2 occcasions where I needed them to avoid a collision. Let us know if your brake lights work in the back either way. I can be reached at email cjstew4@san.rr.com to further detail out this repair if there is a short in your weatherproof plug.
cdru
04-13-2007, 09:36 AM
Besides what he said makes sense, if it "drained out", in theory it should "drain" back in. Of course you would have to figure in the siphoning effect.If it was my van and my family, I would want more then "in theory". Lots of things "in theory" work not quite as expected.
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