When bleeding brakes/ABS there is no fluid coming out of the rear two lines

Tiny
MIKE ALLAN
  • MEMBER
  • 2005 CHEVROLET VENTURE
  • 3.4L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 134,000 MILES
No fluid to front wheels when bleeding the system. On the ABS block the back two lines when removed does not have any fluid coming out but the front two lines do.
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Thursday, July 26th, 2018 AT 9:41 AM

8 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi and thanks for using 2CarPros. Com.

I am not sure what was done to the vehicle to require bleeding. However, here is a list of things which can lead to the ABS system requiring an automated bleed procedure. Additionally, I have attached the procedure for you to see. It requires a scan tool which can actuate the ABS and a brake pressure bleeding tool. Please note that a bad master cylinder can cause this type of issue as well. If you disconnect the lines at the master cylinder, is there pressure from both ports? Also, if you do this, be aware that brake fluid will most likely shoot out. If air gets into the master cylinder, it will require bleeding again.

_________________________________________

ABS Automated Bleed Procedure

Important: In most circumstances a base brake bleed is all that is required for most component replacements (such as wheel cylinders, calipers, brake tubes, and master cylinder) except for brake pressure modulator valve (BPMV) replacement.

Caution: Refer to Brake Fluid Irritant Caution in Service Precautions.

Notice: Refer to Brake Fluid Effects on Paint and Electrical Components Notice in Service Precautions.

The following automated antilock brake system (ABS) bleed procedure is required when one of the following occur:
Manual bleeding at the wheel cylinders does not achieve the desired pedal height or feel.
BPMV replacement
Extreme loss of brake fluid has occurred.
Air ingestion is suspected.
If none of the above conditions apply, use standard bleed procedures.

The auto bleed procedure is used on BOSH 5.3 equipped vehicles. This procedure uses a scan tool to cycle the system solenoid valves and run the pump in order to purge the air from the secondary circuits. These secondary circuits are normally closed off, and are only opened during system initialization at vehicle start up and during ABS operation. The automated bleed procedure opens these secondary circuits and allows any air trapped inside the BPMV to flow out toward the wheel cylinders or calipers where it can be purged out of the system.

Automated Bleed Procedure
Preliminary Inspection
1. Inspect the battery for full charge. Repair the battery and charging system as necessary. Refer to Diagnostic System Check - Vehicle. See: Vehicle > Initial Inspection and Diagnostic Overview > Diagnostic System Check - Vehicle
2. Connect a scan tool to the data link connector (DLC) and select current and history DTCs. Repair any DTCs prior to performing the ABS bleed procedure.
3. Inspect for visual damage and leaks and repair as needed.

Preliminary Setup
1. Raise and vehicle on a suitable support. Refer to Vehicle Lifting.
2. Turn the ignition switch to OFF position.
3. Remove all 4 tires, if necessary.
4. Connect the pressure bleeding tool according to the manufacturer's instructions.
5. Turn the ignition switch to RUN position, engine off.
6. Connect a scan tool and establish communications with the ABS system.
7. Pressurize the bleeding tool to 206-241 kPa (30-35 psi).

Automated Bleed Procedure

1. Notice: The Auto Bleed Procedure may be terminated at any time during the process by pressing the EXIT button. No further Scan Tool prompts pertaining to the Auto Bleed procedure will be given. After exiting the bleed procedure, relieve bleed pressure and disconnect bleed equipment per manufacturers instructions. Failure to properly relieve pressure may result in spilled brake fluid causing damage to components and painted surfaces.

With the pressure bleeding tool at 206-241 kPa (30-35 psi), and all bleeder screws in closed position, select Automated Bleed Procedure on the scan tool and follow the instructions.
2. The first part of the automated bleed procedure will cycle the pump and front release valves for one minute. After the cycling has stopped the scan tool will enter a "cool down" mode and display a 3 minute timer. The auto bleed will not continue until this timer expired, and cannot be overridden.
3. During the next step, the scan tool will request the technician to open one of the bleeder screws. The scan tool will then cycle the respective release valve and pump motor for 1 minute.
4. The scan tool will repeat step 3 for the remaining bleeder screws.
5. With the bleeder tool still attached to the vehicle and maintaining 241 kPa (35 psi), the scan tool will instruct the technician to independently open each bleeder screw for approximately 20 seconds. This should allow any remaining air to be purged from the brake lines.
6. When the automated bleed procedure is completed the scan tool will display the appropriate message.
7. Install all 4 tires, if necessary.
8. Remove pressure from the pressure bleeding tool and then disconnect the tool from the vehicle.
9. Depress the brake pedal to gage pedal height and feel. Repeat steps 1-8 until the pedal is acceptable.
10. Remove the scan tool from the DLC connector.
11. Lower the vehicle.
12. Inspect the brake fluid level in master cylinder.
13. Road test the vehicle while ensuring the brake pedal remains high and firm.

If the vehicle is equipped with a traction control system (TCS), the scan tool will cycle both the ABS and TCS solenoids valves. This bleed procedure is the same as above.

Let me know if this helps or if you have other questions.

Cheers,
Joe
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Thursday, July 26th, 2018 AT 9:17 PM
Tiny
MIKE ALLAN
  • MEMBER
Thank you! I bought van and it has been sitting for couple years. Pedal went to floor when I bought it when doing manual bleed no fluid coming out of abs block rear two ports. Only know that because I have checked everything else and it has led me to the ABS block. My Modis scan tool was used when trying to do a auto bleed, but front wheels will not auto bleed on the scan. I was wondering why it would auto bleed rear wheels and not front wheels? Could it be electrical? Stumped.
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Friday, July 27th, 2018 AT 10:29 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi again. Did you replace the master cylinder?
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Friday, July 27th, 2018 AT 8:04 PM
Tiny
KEN
  • ADMIN
It does sounds like the master cylinder is bad. Can you remove both lines off the master to see if the both have pressure when you push the pedal down?
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Sunday, July 29th, 2018 AT 11:11 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
I am in agreement with Ken. If the master cylinder was not replaced, it sounds like one of the plungers is not working. Let us know what you find.
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Sunday, July 29th, 2018 AT 6:50 PM
Tiny
MIKE ALLAN
  • MEMBER
Master cylinder is working and getting fluid to ABS block just not coming out of back two ports on ABS block for some reason. I have cracked the lines to test master cylinder and ABS to try and find where the problem is and found that fluid is just not coming out of back two ports of ABS block. I have tried manual bleeding several times and auto bleeding several times on it. Did not know if there was something I could try before replacing ABS block. Thanks
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Monday, July 30th, 2018 AT 3:24 PM
Tiny
ASEMASTER6371
  • EXPERT
Good morning

You need to bleed the ABS with a scan tool that has the capability of performing this procedure.

The previous tech gave you the procedure. You need to start there. If you have pressure into the ABS unit, then the master is good.

Start with the bleeding procedure.

Roy
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Tuesday, July 31st, 2018 AT 4:35 AM
Tiny
MIKE ALLAN
  • MEMBER
Already did auto bleed several times as I stated with my scan tool. Two of the wheels will auto bleed and two will not do anything when activating auto bleed on them. Wondering if it could be electrical?
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Tuesday, July 31st, 2018 AT 9:06 PM

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