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  • Bleeding the ABS on a Jimmy

    Does anyone have a clue on how to bleed the ABS system on a 1997 GMC Jimmy. We replaced the brake lines to the rear brakes and now the brakes won't bleed correctly. We think the problem is in the ABS unit(big aluminum thingy with brake line coming from the proportioning valve and going to the brakes). It has bleeders, but apparently they don't work. This is related to my earlier post about my converting said Jimmy to 2wd and the ensuing carnage. Must the Jimmy doesn't like be worked on by Ford people.
    -Walt
    Will translate for go fast parts

  • #2

    Re: Bleeding the ABS on a Jimmy

    Re: Bleeding the ABS on a Jimmy

    Notes

    NOTE: Bleeding is necessary if air has entered the hydraulic brake system.

    It may be necessary to bleed the system at all four wheels if a low fluid level allowed air to enter the system, or the brake pipes have been disconnected at the master cylinder or combination valve. If a pipe is disconnected at one wheel, then only bleed that wheel.

    The time required to bleed the hydraulic system when the master cylinder is removed can be reduced by bleeding the master cylinder before installing it on the vehicle. If the brake pressure modulator valve (BPMV) has been replaced or has air trapped in it, refer to Antilock Brake System.

    NOTE: Brake fluid will damage electrical connections and painted surfaces. Use shop cloths, suitable containers, and fender covers to prevent brake fluid from contacting these areas. Always reseal and wipe off brake fluid containers to prevent spills.

    Tool Required:


    J 28434 Wheel Cylinder Bleeder Wrench
    NOTE: Relieve the vacuum reserve by applying the brakes several times with the ignition "OFF."



    Fill the master cylinder reservoirs with Delco Supreme No. 11 Hydraulic Brake Fluid GM G/M 1052535 or an equivalent DOT 3 motor vehicle brake fluid.
    Maintain the fluid level during bleeding.
    If the master cylinder is suspected to have air in the bore, bleed it before any wheel cylinder or caliper.
    Disconnect the forward brake pipe connection at the master cylinder.
    Allow the brake fluid to flow from the connector port.
    Connect the brake pipe but do not tighten.
    Slowly apply the brake pedal and allow the air to bleed from the loose fitting.
    Tighten the fitting before releasing the pedal.
    Wait 15 seconds.
    Repeat this sequence, including the 15 second wait, until all air is purged from the bore.
    After all air has been removed from the forward connection, repeat this procedure for the rear pipe.
    If the BPMV is replaced or suspected to have air trapped inside, it must be bled next. Refer AntiLock Brake System.
    Bleed each wheel in the following sequence:
    Right rear
    Left rear
    Right front
    Left front
    Attach J 28434 to the wheel cylinder/caliper bleeder valve.
    Immerse the opposite end of the hose into a container partially filled with clean brake fluid.
    Slowly apply the brake pedal one time and hold.
    Loosen the bleeder valve to purge the air from the wheel cylinder/caliper.
    Tighten the bleeder valve and slowly release the pedal.
    Wait 15 seconds.
    Repeat this sequence, including the 15 second wait, until all air is purged from the wheel cylinder/caliper.
    Tighten the bleeder valve to 7 Nm (62 inch lbs.) .
    Continue Steps 5 through 11 at each wheel until the system is bled.
    Check the brake pedal for "sponginess" and the brake warning lamp for an indication of unbalanced pressure. Repeat the bleeding procedure to correct either of these conditions.





    According to Alldata.

    Comment


    • #3

      Re: Bleeding the ABS on a Jimmy

      Re: Bleeding the ABS on a Jimmy

      What about the part where it says refer to the Antilock Brake System, could you pull that up if you have the time?
      -Walt
      Will translate for go fast parts

      Comment


      • #4

        Re: Bleeding the ABS on a Jimmy

        Re: Bleeding the ABS on a Jimmy

        ANTILOCK BRAKE SYSTEM (ABS) BLEEDING PROCEDURE

        NOTE:


        The two person bleed procedure is required when installing a new electro-hydraulic control unit, or when air is suspected to be trapped in the valve body.
        Do not run the Function Test after combination valve or tube adapter replacement.
        Do not drive the vehicle until brake pedal feel is firm.
        Do not re-use brake fluid used during bleeding.
        Vacuum, pressure, or gravity bleeding may be used for base brake bleeding only.
        Two Person ABS Bleeding Procedure


        Raise the vehicle to gain access to the system bleed screws.
        Begin by bleeding the system at the right rear wheel.
        Install clear hose on the bleed screw. Immerse the opposite end of the hose into a container partially filled with clean DOT 3 brake fluid.
        Open the bleed screw 1/2 to 1 full turn.
        Slowly depress the brake pedal until it reaches its full travel and hold until the bleed screw has been tightened. Release the brake pedal and wait 10-15 seconds for the master cylinder pistons to turn to the home position. Repeat until clean, air free brake fluid is present at the wheel bleed screw. This procedure may use more than a pint of fluid per wheel. Check the master cylinder fluid-level every 4 to 6 strokes of the brake pedal to avoid running the system dry. Repeat steps 3 though 5 on the left rear, then right front,then left front.
        Use the scan, sod. to run Function Test four time consecutively while applying the brake pedal firmly. Remove foot from:the brake pedal between each test.
        Rebleed all four wheels using steps 3 through 5 to remove the remaining air from the brake system.
        Evaluate the brake pedal feel before attempting to drive the vehicle and re-bleed as many times as necessary to obtain appropriate pedal feel.





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