Chrysler Front Wheel Drive Cars 4-CYL 1981-1995 Repair Information

Bleeding The ABS System

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This bleeding procedure is only applicable for the anti-lock brake modulator unit; bleeding of the master cylinder and wheel cylinders/brake calipers should be performed the same as vehicles without anti-lock systems.

BENDIX TYPE 4 ABS



See Figures 1, 2, 3, 4, 5 and 6



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Fig. Fig. 1: Bleed the hydraulic modulator primary check valve circuit first ...



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Fig. Fig. 2: ... then the secondary check valve circuit



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Fig. Fig. 3: Step 3 requires bleeding the primary sump circuit ...



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Fig. Fig. 4: ... and bleed the primary accumulator circuit as the 4th step



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Fig. Fig. 5: When bleeding the secondary sump circuit, as well as all of the other circuits, make sure to open the correct bleeder valve



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Fig. Fig. 6: Finally bleed the secondary accumulator circuit

A Diagnostic Readout Box (DRB or DRB II), or the equivalent type of scan tool, is essential to perform the bleeding of the ABS system.

The brake system must be bled any time air is permitted to enter the system through loosened or disconnected lines or hoses, or anytime the modulator is removed. Excessive air within the system will cause a soft or spongy feel in the brake pedal.

When bleeding any part of the system, the reservoir must remain as close to full as possible at all times. Check the level frequently and top off fluid as needed.


WARNING
The base brake and ABS systems can NOT be bled using any type of pressure bleeding equipment. This type of bleeding equipment does not develop the pressure required in the brake hydraulic system to adequately bleed all trapped air. The only method which should be used for bleeding the base brake hydraulic system is the manual procedure of pressurizing the hydraulic system using constant moderate-to-heavy foot pressure on the brake pedal.

The Bendix Anti-lock 4 brake system must be bled as 2 separate brake systems. Proper procedures must be followed if the system is to work correctly. The normal portion of the brake system is bled in the usual fashion with either pressure or manual bleeding equipment and must be fully and properly bled before bleeding the modulator.

To bleed the ABS system, the battery must be relocated outside the vehicle and connected to the vehicle with jumper cables. This allows access to the 4 bleeder screws on top of the modulator assembly. Additionally, the DRB II must be connected to the diagnostic plug before bleeding begins; the DRB II is used to activate the system(s) during the procedure. The 4 components to be bled within the modulator are (in order) the secondary sump, the primary sump, the primary accumulator and the secondary accumulator. The following procedure MUST be used to bleed the modulator assembly.


CAUTION
Wear eye protection when bleeding the modulator assembly and always use a hose on the bleed screw to direct the flow of fluid away from painted surfaces. Bleeding the modulator may result in the release of very high pressure fluid.

To bleed the hydraulic circuits of the brake system modulator assembly, the aid of an assistant will be required to pump the brake pedal.

The Bendix 4 anti-lock brake system modulator does not need to be bled when doing normal servicing procedures such as caliper, hose or wheel cylinder replacement. The modulator does need to be bled when the modulator is removed or the lines are disconnected from the modulator. When servicing this system use DOT 3 brake fluid.

  1. Remove the battery and connect a suitable set of jumper cables from the battery to the vehicle.
  2.  
  3. Remove the acid shield covering the modulator.
  4.  
  5. Fill the master cylinder reservoir to the proper level.
  6.  
  7. Bleed the primary check valve circuit as follows.
    1. Put a bleeder tube on the primary check valve circuit bleeder screw and place the other end into a suitable container with approximately 2 in. (51mm) of brake fluid. Make sure the bleeder hose is submerged in brake fluid.
    2.  
    3. Have an assistant apply heavy and constant pressure on the brake pedal.
    4.  
    5. Loosen the primary check valve circuit screw.
    6.  
    7. Bleed the primary check valve circuit until a clear air free flow of brake fluid comes from the bleeder hose or the brake pedal bottoms.
    8.  
    9. Close bleeder valve and remove the bleeder hose.
    10.  

  8.  
  9. Bleed the secondary check valve circuit as follows.
    1. Put a bleeder tube on the secondary check valve circuit bleeder screw and place the other end into a suitable container with approximately 2 in. (51mm) of brake fluid. Make sure the bleeder hose is submerged in brake fluid.
    2.  
    3. Have an assistant apply heavy and constant pressure on the brake pedal.
    4.  
    5. Loosen the secondary check valve circuit bleeder screw.
    6.  
    7. Bleed the secondary check valve circuit until a clear air free flow of brake fluid comes from the bleeder hose or the brake pedal bottoms.
    8.  
    9. Close bleeder valve and remove the bleeder hose.
    10.  

  10.  
  11. Bleed the primary sump as follows.
    1. Put a bleeder tube on the primary sump bleeder screw and place the other end into a suitable container with approximately 2 in. (51mm) of brake fluid. Make sure the bleeder hose is submerged in brake fluid.
    2.  
    3. Have an assistant apply heavy and constant pressure on the brake pedal.
    4.  
    5. Loosen the primary sump bleeder screw.
    6.  
    7. Using the DRB scan tool select the bleed ABS hydraulic unit mode then select the primary circuit.
    8.  
    9. Bleed the primary sump until a clear air free flow of brake fluid comes from the bleeder hose or the brake pedal bottoms.
    10.  
    11. Close bleeder valve and remove the bleeder hose.
    12.  

  12.  
  13. Bleed the primary accumulator as follows.
    1. Put a bleeder tube on the primary accumulator bleeder screw and place the other end into a suitable container with approximately 2 in. (51mm) of brake fluid. Make sure the bleeder hose is submerged in brake fluid.
    2.  
    3. Have an assistant apply heavy and constant pressure on the brake pedal.
    4.  
    5. Using the DRB scan tool select bleed ABS hydraulic unit mode then select the primary circuit.
    6.  
    7. Loosen the bleeder screw.
    8.  
    9. Bleed the until a clear air free flow of brake fluid comes from the bleeder hose.
    10.  
    11. Repeat the bleed procedure without using the DRB scan tool.
    12.  
    13. Close bleeder valve and remove the bleeder hose.
    14.  

  14.  
  15. Bleed the secondary sump as follows.
    1. Put a bleeder tube on the secondary sump bleeder screw and place the other end into a suitable container with approximately 2 in. (51mm) of brake fluid. Make sure the bleeder hose is submerged in brake fluid.
    2.  
    3. Have an assistant apply light and constant pressure on the brake pedal.
    4.  
    5. Loosen the secondary sump bleeder screw.
    6.  
    7. Using the DRB scan tool select the bleed ABS hydraulic unit mode then select the secondary circuit valves.
    8.  
    9. Bleed the secondary sump until a clear air free flow of brake fluid comes from the bleeder hose or the brake pedal bottoms.
    10.  
    11. Close bleeder valve and remove the bleeder hose.
    12.  

  16.  
  17. Bleed the secondary accumulator as follows.
    1. Put a bleeder tube on the secondary accumulator bleeder screw and place the other end into a suitable container with approximately 2 in. (51mm) of brake fluid. Make sure the bleeder hose is submerged in brake fluid.
    2.  
    3. Have an assistant apply heavy and constant pressure on the brake pedal.
    4.  
    5. Loosen the secondary sump bleeder screw.
    6.  
    7. Using the DRB scan tool select bleed ABS hydraulic unit. Then select secondary circuit valves.
    8.  
    9. Bleed the secondary sump until a clear air free flow of brake fluid comes from the bleeder hose or the brake pedal bottoms.
    10.  
    11. Repeat the bleeding procedure without using the DRB scan tool.
    12.  
    13. Close bleeder valve and remove the bleeder hose.
    14.  

  18.  
  19. Fill the master cylinder to the proper level.
  20.  
  21. Install the acid shield and the battery.
  22.  
  23. Road test the vehicle to check for proper brake system operation.
  24.  

BENDIX TYPE 6 ABS



See Figure 7

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Fig. Fig. 7: The 4 bleeder valves (primary accumulator, secondary accumulator, primary sump and secondary sump) are necessary for system bleeding

A Diagnostic Readout Box (DRB or DRB II), or the equivalent type of scan tool, is essential to perform the bleeding of the ABS system.

The brake system must be bled any time air is permitted to enter the system through loosened or disconnected lines or hoses, or anytime the modulator is removed. Excessive air within the system will cause a soft or spongy feel in the brake pedal.

When bleeding any part of the system, the reservoir must remain as close to full as possible at all times. Check the level frequently and top off fluid as needed.

The Bendix Anti-lock 6 brake system must be bled as 2 separate brake systems. Proper procedures must be followed if the system is to work correctly. The normal portion of the brake system is bled in the usual fashion with either pressure or manual bleeding equipment and must be fully and properly bled before bleeding the modulator.

To bleed the ABS system, the battery must be relocated outside the vehicle and connected to the vehicle with jumper cables. This allows access to the 4 bleeder screws on top of the modulator assembly. Additionally, the DRB II must be connected to the diagnostic plug before bleeding begins; the DRB II is used to activate the system(s) during the procedure. The 4 components to be bled within the modulator are (in order) the secondary sump, the primary sump, the primary accumulator and the secondary accumulator. Use the following procedure to bleed the modulator assembly.


CAUTION
Wear eye protection when bleeding the modulator assembly and always use a hose on the bleed screw to direct the flow of fluid away from painted surfaces. Bleeding the modulator may result in the release of very high pressure fluid.

To bleed the hydraulic circuits of the brake system modulator assembly, the aid of an assistant will be required to pump the brake pedal.

  1. Connect a clear hose to the secondary sump bleeder screw and route the hose to a clear container.
  2.  
  3. Either install and pressurize the pressure bleeding equipment at the master cylinder or have an assistant provide light and constant pressure on the brake pedal.
  4.  
  5. Open the bleeder screw about 1 / 2 - 3 / 4 turn. Use the DRB II to select the ACTUATE VALVES test; actuate the left front build/decay valve.
  6.  
  7. Bleed until the fluid flows free of air bubbles or until the brake pedal bottoms.
  8.  
  9. Tighten the bleeder screw and release the brake pedal if it was being held.
  10.  
  11. Repeat Steps 2 through 5 until the fluid is free of air bubbles. Remember to check the fluid reservoir level periodically.
  12.  
  13. Select and actuate the right rear build/decay valve and perform Steps 2-5 until the fluid flows without air bubbles.
  14.  
  15. Move the bleeder tube to the primary sump bleeder screw.
  16.  
  17. Pressurize the pressure bleeding equipment at the master cylinder or have an assistant provide light and constant pressure on the brake pedal.
  18.  
  19. Open the bleeder screw about 1 / 2 - 3 / 4 turn. Using the DRB II, actuate the right front build/decay valve.
  20.  
  21. Bleed until the fluid flows free of air bubbles or until the brake pedal bottoms.
  22.  
  23. Tighten the bleeder screw and release the brake pedal if it was being held.
  24.  
  25. Repeat Steps 2 through 5 until the fluid is free of air bubbles. Remember to check the fluid reservoir level periodically.
  26.  
  27. Select and actuate the left rear build/decay valve. Perform Steps 2-5 until the fluid runs free of air bubbles.
  28.  
  29. Move the bleeder tube to the primary accumulator bleeder screw.
  30.  
  31. Pressurize the pressure bleeding equipment at the master cylinder or have an assistant provide light and constant pressure on the brake pedal.
  32.  
  33. Open the bleeder screw about 1 / 2 - 3 / 4 turn. Using the DRB II, actuate the right front/left rear isolation valve.
  34.  
  35. Bleed until the fluid flows free of air bubbles or until the brake pedal bottoms.
  36.  
  37. Tighten the bleeder screw and release the brake pedal if it was being held.
  38.  
  39. Repeat Steps 2 through 5 until the fluid is free of air bubbles. Check the fluid reservoir level periodically.
  40.  
  41. Select and actuate the right front build/decay valve. Perform Steps 2-5 until the fluid runs free of air bubbles.
  42.  
  43. Move the bleeder tube to the secondary accumulator bleeder screw.
  44.  
  45. Pressurize the pressure bleeding equipment at the master cylinder or have an assistant provide light and constant pressure on the brake pedal.
  46.  
  47. Open the bleeder screw about 1 / 2 - 3 / 4 turn. Using the DRB II, actuate the left front/right rear isolation valve.
  48.  
  49. Bleed until the fluid flows free of air bubbles or until the brake pedal bottoms.
  50.  
  51. Tighten the bleeder screw and release the brake pedal if it was being held.
  52.  
  53. Repeat Steps 2 through 5 until the fluid is free of air bubbles. Check the fluid reservoir level periodically.
  54.  
  55. Select and actuate the left front build/decay valve. Perform Steps 2-5 until the fluid runs free of air bubbles.
  56.  
  57. Remove the bleeding apparatus; fill the brake fluid reservoir to the correct level and install the cap.
  58.  

 
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