GM Camaro/Firebird 1993-1998 Repair Guide

Bleeding the ABS System with Traction Control

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WARNING
Do NOT allow brake fluid to spill on or come in contact with the vehicle's finish as it will remove the paint. In case of a spill, immediately flush the area with water.

SYSTEM FILLING



The master cylinder reservoirs must be kept properly filled to prevent air from entering the system. No special filling procedures are required because of the anti-lock system.

When adding fluid, use only DOT 3 fluid; the use of DOT 5 or silicone fluids is specifically prohibited. Use of improper or contaminated fluid may cause the fluid to boil or cause the rubber components in the system to deteriorate. Never use any fluid with a petroleum base or any fluid which has been exposed to water or moisture.

SYSTEM BLEEDING



Before bleeding the ABS brake system, the front and rear displacement cylinder pistons must be returned to the topmost position. This requires the use of a Tech 1® scan tool to perform the rehoming procedure.

Rehome Procedure
  1. Using a Tech 1®, select "F6: Bleed Prep.'' The bleed prep function cannot be performed if current DTC's are present. If DTC's are present, the vehicle must be repaired and the codes cleared before performing the bleed prep function.
  2.  
  3. The entire brake system should now be bled using the pressure or manual bleeding procedures outlined later in this section.
  4.  
  5. If the amber "ABS" or "TCS" warning lights are turned ON and remain ON after about 10 seconds, the bleeding procedure must be stopped and a Tech 1® scan tool used to diagnose the ABS or TCS malfunction.
  6.  
  7. Do not place your foot on the brake pedal through this entire procedure unless specifically instructed to do so.
  8.  

Pressure Bleeding

The pressure bleeding equipment must be of the diaphragm type. It must have a rubber diaphragm between the air supply and the brake fluid to prevent air, moisture and other contaminants from entering the hydraulic system.

  1. Clean the master cylinder fluid reservoir cover and surrounding area, then remove the cover.
  2.  
  3. Add fluid, if necessary to obtain a proper fluid level.
  4.  
  5. Connect bleeder adapter J 35589, or equivalent, to the brake fluid reservoir, then connect the bleeder adapter to the pressure bleeding equipment.
  6.  
  7. Adjust the pressure bleed equipment to 5-10 psi (35-70 kPa) and wait about 30 seconds to be sure there is no leakage.
  8.  
  9. Adjust the pressure bleed equipment to 30-35 psi (205-240 kPa).
  10.  
  11. Using a Tech 1® scan tool select "F6: Bleed Prep.'' function and follow the scan tool as instructed. After completion of the bleed prep function, proceed with the following step.
  12.  


WARNING
Use a shop rag to catch the escaping brake fluid. Be careful not to let any fluid run down the motor pack base or into the electrical connector.

  1. With the pressure bleeding equipment connected and pressurized, proceed as follows:
    1. Attach a clear plastic bleeder hose to the rearward bleeder valve on the hydraulic modulator. Submerge the other end of the hose in a clean container partially filled with clean brake fluid.
    2.  
    3. Slowly open the bleeder valve and allow fluid to flow until no air is seen in the fluid.
    4.  
    5. Close the valve when fluid flows out without any air bubbles.
    6.  
    7. Repeat Steps 7b and 7c until no air bubbles are present.
    8.  
    9. Relocate the bleeder hose on the forward hydraulic modulator bleed valve and repeat Steps 7a through 7d.
    10.  

  2.  
  3. Tighten the bleeder valve to 80 inch lbs. (9 Nm).
  4.  
  5. Proceed to bleed the master cylinder brake pipe connections as follows with the pressure bleeding equipment connected and pressurized:
    1. Slowly loosen the forward brake pipe tube nut on the master cylinder and check for air in the escaping fluid.
    2.  
    3. When the air flow ceases, immediately tighten the tube nut. Tighten the tube nut to 24 ft. lbs. (32 Nm).
    4.  

  6.  
  7. Repeat Steps 8a and 8b for the rearward master cylinder brake pipe connection.
  8.  
  9. Proceed to bleed the brake combination valve connections as follows, with the pressure bleeding equipment connected and pressurized:
    1. Slowly loosen the forward brake pipe tube nut on the brake combination valve and check for air in the escaping fluid.
    2.  
    3. When the air flow ceases, immediately tighten the tube nut. Tighten the brake combination tube nut to 13 ft. lbs. (18 Nm).
    4.  

  10.  
  11. Repeat Steps 9a and 9b for the rearward brake combination valve pipe connection.
  12.  
  13. Proceed to bleed the ABS hydraulic modulator brake connections as follows, with the pressure bleeding equipment connected and pressurized:
    1. Slowly loosen the forward brake pipe tube nut on the ABS hydraulic modulator and check for air in the escaping fluid.
    2.  
    3. When the air flow ceases, immediately tighten the tube nut. Tighten the ABS hydraulic modulator tube nut to 24 ft. lbs. (32 Nm).
    4.  

  14.  
  15. Repeat Steps 10a and 10b for the remaining ABS hydraulic modulator brake pipe connections, moving from front to rear.
  16.  
  17. Proceed to bleed the TCS hydraulic modulator brake connections as follows, with the pressure bleeding equipment connected and pressurized:
    1. Slowly loosen the forward brake pipe tube nut on the TCS hydraulic modulator and check for air in the escaping fluid.
    2.  
    3. When the air flow ceases, immediately tighten the tube nut. Tighten the TCS hydraulic modulator tube nut to 24 ft. lbs. (32 Nm).
    4.  

  18.  
  19. Repeat Steps 11a and 11b for the remaining TCS hydraulic modulator brake pipe connections.
  20.  
  21. Raise and safely support the vehicle.
  22.  
  23. Proceed, as outlined in the following steps, to bleed the rear wheel brakes:
    1. Attach a clear plastic bleeder hose to the bleeder valve at the right rear wheel, then submerge the opposite hose end in a clean container partially filled with clean brake fluid.
    2.  
    3. Slowly open the bleeder valve and allow the fluid to flow.
    4.  
    5. Close the valve when fluid begins to flow without any air bubbles. Tap lightly on the caliper or backing plate to dislodge any trapped air bubbles.
    6.  
    7. Relocate the bleeder hose to the left rear wheel bleeder valve and repeat steps 12a-12c.
    8.  

  24.  
  25. Remove the pressure from the pressure bleeding equipment.
  26.  
  27. Attach a clear plastic bleeder hose to the right front wheel bleeder valve and submerge the opposite hose end in a clean container partially filled with clean brake fluid.
  28.  
  29. Turn the ignition to the RUN position with the engine OFF .
  30.  
  31. Open the bleeder valve and apply the brake until the red BRAKE warning lamp turns ON. This shuttles the brake pressure differential warning valve.
  32.  
  33. Close the bleeder valve.
  34.  
  35. Reapply pressure to the pressure bleeding equipment.
  36.  
  37. Turn the ignition to the OFF position.
  38.  


WARNING
Do NOT reapply the brakes after closing the bleeder valve.

  1. Carefully lower the vehicle.
  2.  
  3. Repeat the entire step 7.
  4.  
  5. Raise and safely support the vehicle.
  6.  
  7. Repeat the entire step 13.
  8.  
  9. Proceed to bleed the front brakes as follows:
    1. Attach a clear plastic hose to the right front wheel bleeder valve and submerge the other end of the hose in a clean container partially filled with clean brake fluid.
    2.  
    3. Slowly open the bleeder valve and allow the fluid to flow.
    4.  
    5. Close the valve when the fluid begins to flow without any air bubbles. Tap lightly on the caliper to dislodge any trapped air bubbles.
    6.  
    7. Relocate the bleeder hose to the left front wheel and repeat steps 25a-25c.
    8.  

  10.  
  11. Continuing with the Tech 1® scan tool, press "ENTER" to initialize the TCS modulator for bleeding.
  12.  
  13. Proceed as follows to bleed the rear wheel brakes only:
    1. Attach a clear plastic hose to the right rear wheel bleeder valve and submerge the other end of the hose in a clean container partially filled with clean brake fluid.
    2.  
    3. Slowly open the bleeder valve and allow the fluid to flow.
    4.  
    5. Close the valve when the fluid begins to flow without any air bubbles. Tap lightly on the caliper or backing plate to dislodge any trapped air bubbles.
    6.  
    7. Relocate the bleeder hose to the left rear wheel and repeat steps 27a-27c.
    8.  

  14.  

This procedure must be followed to be sure all air has been removed from the TCS hydraulic modulator.

  1. Carefully lower the vehicle.
  2.  
  3. Remove the pressure bleeding equipment, including bleeder adapter J 35589.
  4.  
  5. Check the fluid level in the master cylinder reservoir and add if necessary. Install the reservoir cap.
  6.  
  7. With the ignition turned to the RUN position, apply the brake pedal with moderate force and hold it. Note the pedal travel and feel. If the pedal feels firm and constant and the pedal travel is not excessive, start the engine. With the engine running, recheck the pedal travel. If it's still firm and constant and pedal travel is not excessive, go to Step 33.
  8.  
  9. If the pedal feels soft or has excessive travel either initially or after the engine is started, the following procedure may be used:
    1. With the Tech 1® scan tool, "release'' then "apply'' each ABS motor 2-3 times and cycle each ABS solenoid 5-10 times. When finished, be sure to "apply'' the front and rear motors on the ABS hydraulic modulator. "Apply" and "release" each TCS motor 2-3 times. When finished, make sure to "release" each motor on the TCS hydraulic modulator. This will ensure all trapped air has been removed from the ABS and TCS hydraulic modulator bores.
    2.  
    3. Repeat the bleeding procedure, starting with Step 1.
    4.  

  10.  
  11. Road test the vehicle. Make several normal (non-ABS) stops and from a moderate speed to be sure the brakes are operating properly.
  12.  

Manual Bleeding
  1. Clean the master cylinder fluid reservoir cover and surrounding area, then remove the cover.
  2.  
  3. Add fluid, if necessary to obtain a proper fluid level, then put the reservoir cover back on.
  4.  
  5. Using a Tech 1® scan tool, select the "F6: Bleed Prep" function and follow the scan tool as directed. After completion of the bleed prep function proceed with step 4.
  6.  
  7. Prime the ABS hydraulic modulator/master cylinder assembly as follows:
    1. Attach a bleeder hose to the rearward bleeder valve on the ABS hydraulic modulator, then submerge the opposite hose end in a clean container partially filled with clean brake fluid.
    2.  
    3. Slowly open the rearward bleeder valve one half to on full turn.
    4.  
    5. Depress and hold the brake pedal until the fluid begins to flow.
    6.  
    7. Close the valve, then release the brake pedal.
    8.  
    9. Repeat Steps 4b-4d until no air bubbles are present.
    10.  
    11. Relocate the bleeder hose to the forward hydraulic modulator bleeder valve, then repeat Steps 4a-4e.
    12.  

  8.  
  9. Once the fluid is seen to flow from both modulator bleeder valves, the ABS modulator/master cylinder assembly is sufficiently full of fluid. However, it may not be completely purged of air. At this point, move to the wheel brakes and bleed them. This ensures that the lowest points in the system are completely free of air and then the assembly can purged of any remaining air.
  10.  
  11. Remove the fluid reservoir cover. Fill to the correct level, if necessary, then fasten the cover.
  12.  
  13. Raise and safely support the vehicle.
  14.  
  15. Proceed, as outlined in the following steps, to bleed the wheel brakes in the following sequence: right rear, left front, right front, then left rear.
    1. Attach a clear plastic bleeder hose to the bleeder valve at the wheel, then submerge the opposite hose end in a clean container partially filled with clean brake fluid.
    2.  
    3. Open the bleeder valve.
    4.  
    5. Have an assistant slowly depress the brake pedal.
    6.  
    7. Close the valve and slowly release the release the brake pedal.
    8.  
    9. Wait 5 seconds.
    10.  
    11. Repeat Steps 8a-8e until the brake pedal feels firm at half travel and no air bubbles are observed in the bleeder hose. To assist in freeing the entrapped air, tap lightly on the caliper or braking plate to dislodge any trapped air bubbles.
    12.  

  16.  
  17. Repeat Step 8 for the remaining brakes in the sequence given earlier.
  18.  
  19. Continuing with the Tech 1®, press "ENTER" to initialize the TCS modulator for bleeding. Follow the scan tool instructions.
  20.  
  21. Proceed as follows to bleed the rear wheel brakes only:
    1. Attach a clear plastic hose to the right rear wheel bleeder valve and submerge the other end of the hose in a clean container partially filled with clean brake fluid.
    2.  
    3. Slowly open the bleeder valve.
    4.  
    5. Have an assistant slowly depress the bleeder valve.
    6.  
    7. Close the valve when the fluid begins to flow without any air bubbles. Tap lightly on the caliper or backing plate to dislodge any trapped air bubbles.
    8.  
    9. Relocate the bleeder hose to the left rear wheel and repeat steps 11a-11d.
    10.  

  22.  

This procedure must be followed to ensure all air has been removed from the TCS hydraulic modulator.

  1. Carefully lower the vehicle.
  2.  
  3. Remove the reservoir cover, then fill to the correct level with brake fluid and replace the cap.
  4.  
  5. Bleed the ABS hydraulic modulator as follows:
    1. Attach a clear plastic bleeder hose to the rearward bleeder valve on the modulator, then submerge the opposite hose end in a clean container partially filled with clean brake fluid.
    2.  
    3. Have an assistant depress the brake pedal with moderate force.
    4.  
    5. Slowly open the rearward bleeder valve one half to one full turn, and allow the fluid to flow.
    6.  
    7. Close the valve, then slowly release the brake pedal.
    8.  
    9. Wait 5 seconds.
    10.  
    11. Repeat Steps 14b-14e until no air bubbles are present.
    12.  
    13. Relocate the bleeder hose to the forward hydraulic modulator bleeder valve, then repeat Steps 14a-14f.
    14.  

  6.  
  7. Check the brake fluid and add if necessary. Don't forget to put the reservoir cap back on.
  8.  
  9. With the ignition turned to the RUN position, apply the brake pedal with moderate force and hold it. Note the pedal travel and feel. If the pedal feels firm and constant and the pedal travel is not excessive, start the engine. With the engine running, recheck the pedal travel. If it's still firm and constant and pedal travel is not excessive, go to Step 33.
  10.  
  11. If the pedal feels soft or has excessive travel either initially or after the engine is started, the following procedure may be used:
    1. With the Tech 1® scan tool, "release'' then "apply'' each ABS motor 2-3 times and cycle each ABS solenoid 5-10 times. When finished, be sure to "apply'' the front and rear motors on the ABS hydraulic modulator. "Apply" and "release" each TCS motor 2-3 times. When finished, make sure to "release" each motor on the TCS hydraulic modulator. This will ensure all trapped air has been removed from the ABS and TCS hydraulic modulator bores.
    2.  
    3. Repeat the bleeding procedure, starting with Step 1.
    4.  

  12.  
  13. Road test the vehicle. Make several normal (non-ABS) stops and from a moderate speed to be sure the brakes are operating properly.
  14.  

 
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