GM Blazer/Jimmy/Typhoon/Bravada 1983-1993 Repair Guide

Brake/Clutch Release Switches

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See Figure 1

All factory or dealer installed cruise control systems for these vehicles are equipped with either a brake or clutch release switch. The purpose of the switch is to deactivate the system when the driver begins to depress the pedal. Most of the switches found on earlier models are vacuum break switches (vacuum release valves) which will therefore have a vacuum line attached to the rear or side of the switch. A vacuum break switch is used to quickly vent vacuum to the atmosphere so a vacuum controlled servo may return the throttle to the idle position. Later models may use a vacuum switch, an electric switch or a combined vacuum and electric switch, depending upon the model and application. Some vehicles may combine the cruise control release and stop lamp (brake light) switches into a single component with multiple connections. Electric switches are commonly used to disengage the cruise control by either completing/breaking a circuit or by signaling a control module.



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Fig. Fig. 1: Early model cruise control release switches, wiring and vacuum hoses

All switches are normally mounted using an interference clip which holds ribs on the switch's neck. These switches are self-adjusting when installed properly.

REMOVAL & INSTALLATION



See Figures 2, 3 and 4

  1. If equipped with an electric or vacuum/electric switch, disconnect the negative battery cable.
  2.  
  3. Disengage the vacuum line and/or the electrical connector(s) from the switch.
  4.  
  5. For interference fit switches, grasp the switch and withdraw it from the clip. If necessary the clip can be removed from the pedal bracket as well. Some clips are designed with lock tangs and may be pivoted in order to pull them from the bracket. On these, you may twist the switch and retainer clip together and withdraw them as an assembly. Other clips are also an interference fit and must be squeezed and withdrawn.
  6.  

To install:
  1. If removed, install the retainer to the pedal bracket.
  2.  
  3. With the pedal depressed so it will not interfere, insert and fully seat the switch into the clip on the pedal bracket.
  4.  
  5. In order to adjust the switch, grasp the pedal and pull it fully back against the stop. While pulling the pedal backwards, a clicking sound should be heard as the switch is pushed backwards in the clip until it is in the proper position. Make sure the switch plunger is seated when the pedal is released and that the plunger fully extends as the pedal is depressed. Check the switch operation and adjust again, if necessary.
  6.  



Click image to see an enlarged view

Fig. Fig. 2: Examples of clip mounted cruise control release switches (vacuum release valves)



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Fig. Fig. 3: View of an early model, cruise control/brake light combination switch



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Fig. Fig. 4: View of a late model vacuum release valve - automatic transmission only

  1. Engage the vacuum line and/or electrical connector(s) to the switch.
  2.  
  3. If removed, connect the negative battery cable.
  4.  
  5. Verify proper switch operation.
  6.  

ADJUSTMENT



Clip-mounted switches should be found on all factory and dealer installed systems through 1993. These switches are automatically adjusted during installation. The clip holds the switch in position by the raised ribs located on the switch's neck.

 
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