Jeep Wagoneer/Commando/Cherokee 1984-1998

Hydraulic Control Unit (HCU)

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Removal & Installation



See Figure 1

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

  1. Remove the air cleaner and the clamp that secures the air cleaner hose and pipe to the fender apron.
  2.  
  3. Place a suitable size drain container under the master cylinder reservoir hoses and disengage the reservoir hoses from the HCU.
  4.  
  5. Remove the reservoir and disengage the pump motor and solenoid harness wires at the HCU.
  6.  
  7. Tag and disconnect the HCU hydraulic lines at the HCU.
  8.  
  9. Move the HCU harness and air cleaner hose pipe aside for access to the HCU bracket fasteners and remove the fasteners.
  10.  
  11. Remove the HCU, being careful not to damage the brake lines or master cylinder.
  12.  

To install:
  1. Engage the reservoir hoses to the HCU pipes and position the HCU assembly on the bracket. Tighten the fasteners to 92-112 inch lbs. (10-13 Nm).
  2.  
  3. Install and tighten the HCU hydraulic lines. Check the lines and hose routing so that they are clear of engine components and have no kinks.
  4.  
  5. Fill the master cylinder with DOT 3 brake fluid and bleed the brake system. Refer to the bleeding procedure for this system in this section.
  6.  
  7. Install the air cleaner and hoses. Fasten the air cleaner hose to the fender apron with the clamp.
  8.  
  9. Test drive the vehicle and test for proper brake operation.
  10.  



Click image to see an enlarged view

Fig. Fig. 1: HCU is located on the left side of the engine compartment next to the brake master cylinder. (1) HCU pump motor harness and (2) HCU solenoid harness connector locations are shown

 
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