GM Full Size Vans 1987-1997 Repair Guide

Combination Valve

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This valve is used on all models with disc brakes. The valve itself is a combination of:

  1. The metering valve, which will not allow the front disc brakes to engage until the rear brakes contact the drum.
  2.  
  3. The failure warning switch, which notifies the driver if one of the systems has a leak.
  4.  
  5. The proportioner which limits rear brake pressure and delays rear wheel skid.
  6.  

REMOVAL & INSTALLATION



1987-95 Models

See Figure 1

  1. Disconnect the hydraulic lines and plug to prevent dirt from entering the system.
  2.  



Click image to see an enlarged view

Fig. Fig. 1: Combination valve installation - 1987-95 models

  1. Disconnect the warning switch harness.
  2.  
  3. Remove the retaining bolts and remove the valve. Tighten the bolts to 18 ft. lbs. (25 Nm).
  4.  
  5. Install the valve and bleed the brake system.
  6.  

1996-97 Models
  1. Raise the vehicle and support it with jackstands.
  2.  
  3. Remove the shield retainers and shield from the vehicle.
  4.  
  5. Disconnect the brake lines at the valve. Plug or cap the lines and ports.
  6.  
  7. Unplug the electrical connector.
  8.  
  9. Unfasten the Allen bolts connecting the valve to the Brake Pressure Modulator Valve (BPMV).
  10.  
  11. Remove the valve, then transfer the tubes to the new valve.
  12.  

To install:
  1. Install the tubes until they are firmly seated.
  2.  
  3. Install the valve. Tighten the bolts in two steps, first tighten the Allen bolts to 6 ft. lbs. (8 Nm) and then to 12 ft. lbs. (16 Nm).
  4.  
  5. Connect the brake lines and engage the electrical connector.
  6.  
  7. Install the shield and tighten the retainers to 8 ft. lbs. (12 Nm).
  8.  
  9. Bleed the system.
  10.  

 
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