Mazda Trucks 1987-1993 Repair Guide

Hydraulic Control Unit (HCU)

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PUMP TESTING



  1. Disconnect the HCU pump motor electrical plug.
  2.  
  3. Connect a Digital Volt/Ohm Meter (DVOM) across the two pump terminals and record the reading.
  4.  
  5. The reading should be between 52-68 Ohms
  6.  
  7. If not, replace the pump motor.
  8.  

REMOVAL & INSTALLATION



  1. Disconnect the battery ground cable.
  2.  
  3. Unplug the 8-pin connector from the unit, and the 4-pin connector from the pump motor.
  4.  
  5. Disconnect the 5 inlet and outlet tubes from the unit. Immediately plug the ports.
  6.  
  7. Remove the 3 unit attaching nuts and lift out the unit.
  8.  
  9. Installation is the reverse of removal. Torque the mounting nuts to 12-18 ft. lbs. and the tube fittings to 10-18 ft. lbs.
  10.  

After reconnecting the battery, it may take 10 miles or more of driving for the Powertrain Control Module to relearn its driveability codes.

  1. Bleed the brakes.
  2.  

 
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