GM Full-Size Trucks 1988-1998 Repair Information

Vacuum Modulator

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REMOVAL & INSTALLATION



See Figure 1

This applies to the THM 400 only.

  1. Raise and support the front end on jackstands.
  2.  
  3. Disconnect the vacuum line at the modulator.
  4.  
  5. Remove the screw and retaining clamp.
  6.  



Click image to see an enlarged view

Fig. Fig. 1: Vacuum modulator on the THM400

  1. Remove the modulator. Be careful, some fluid may run out.
  2.  

To install:
  1. Install the modulator.
  2.  
  3. Install the vacuum line. Be careful not to kink the vacuum line during installation. Replace any lost fluid.
  4.  

 
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