GM Full Size Vans 1987-1997 Repair Guide

EHCU Valve/BPMV (4WAL)

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REMOVAL & INSTALLATION



Except 1996-97 Models

See Figures 1 and 2



Click image to see an enlarged view

Fig. Fig. 1: EHCU/BPMV mounting



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Fig. Fig. 2: ECHU/BPMV brake line connections

The EHCU valve is not serviceable. Replace the valve only when defective.

  1. Disconnect the negative battery cable.
  2.  
  3. Raise the vehicle and support it with jackstands.
  4.  
  5. Tag and disengage the electrical connections from the EHCU/BPMV.
  6.  
  7. Disconnect the brake pipes from the EHCU/BPMV.
  8.  
  9. Unfasten the retaining bolts and remove the EHCU/BPMV from its mounting bracket.
  10.  
  11. Remove the EHCU/BPMV from the vehicle.
  12.  

To install:
  1. Install the EHCU/BPMV onto the bracket. Tighten the mounting bolt to 84 inch lbs. (9 Nm).
  2.  
  3. Install the EHCU/BPMV and tighten the retainers to 55 ft. lbs. (75 Nm).
  4.  
  5. Connect the electrical connectors and hydraulic lines. Torque the line fittings to 16 ft. lbs. (25 Nm).
  6.  
  7. Bleed the system and the EHCU/BPMV.
  8.  
  9. Connect the negative battery cable, pump the brakes before road test and road test
  10.  

1996-97 Models

See Figures 3 and 4



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Fig. Fig. 3: EHCU/BPMV mounting - 1996-97 models



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Fig. Fig. 4: EHCU/BPMV exploded view - 1996-97 models

  1. Disconnect the negative battery cable.
  2.  
  3. Raise and safely support the vehicle.
  4.  
  5. Remove the EHCU shield retainers and shield.
  6.  

See Figure 5



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Fig. Fig. 5: The EHCU is located on the frame rail and is protected by a shield

  1. Unplug the electrical connectors from the unit.
  2.  
  3. Using a flare wrench, disconnect the hydraulic lines from the unit.
  4.  
  5. Unfasten the bolts and remove the BPMV and bracket.
  6.  
  7. Remove the bolts that hold the unit to the bracket.
  8.  
  9. If necessary, unfasten the EBCM-to-BPMV retaining bolts and separate the units.
  10.  
  11. Unfasten the Allen bolts, then remove the combination valve.
  12.  
  13. Remove the transfer tubes.
  14.  

To install:
  1. Install the transfer tubes into the combination valve until fully seated.
  2.  
  3. Engage the combination valve to the BPMV and tighten the Allen bolts in two steps to 6 ft. lbs. (8 Nm) and then to 12 ft. lbs. (16 Nm).
  4.  
  5. Install a new gasket and engage the EBCM to the BPMV and tighten the retainers to 39 in. lbs. (5 Nm).
  6.  
  7. Install the unit onto the bracket and tighten the bolts to 7 ft. lbs. (9 Nm).
  8.  
  9. Install the unit and bracket and tighten the bolts to 9 ft. lbs. (12 Nm).
  10.  
  11. Connect the hydraulic lines. Torque the fittings to 22 ft. lbs. (30 Nm).
  12.  
  13. Engage the electrical connections and replace the EHCU shield and tighten the retainers to 8 ft. lbs. (12 Nm).
  14.  
  15. Connect the negative battery cable.
  16.  
  17. Bleed the hydraulic system.
  18.  
  19. Lower the vehicle.
  20.  

 
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