GM Astro/Safari 1985-1996 Repair Guide

OPERATION

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The controller interprets the position of the servo, position of the mode control switches and the output of the speed sensor. The servo consists of a vacuum tank and an open solenoid valve to vent the diaphragm chamber to atmosphere, except for the electric systems which use an electric stepper motor. The digital ratio adapter is a solid state device that is used to change the signal from the vehicle speed sensor to the a digital signal. The adapter is matched to the final drive of each vehicle and most be replaced with the proper adapter to match the final drive. This unit is located inside the vehicle speed sensor at the transmission.

DIAGNOSIS



See Figures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 and 14

A problem can be mechanical, electrical and/or vacuum.

Initial Inspection
  1. Check for bare, broken or disconnected wires and vacuum hoses.
  2.  
  3. Make sure the servo and throttle linkages operate freely and smoothly.
  4.  
  5. Check the "Ignition/Gauges'' 20 amp fuse.
  6.  
  7. Verify that the check valve functions properly.
  8.  
  9. If no problems are found, refer to the "Cruise Control'' diagnostic and wiring charts in this section.
  10.  



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Fig. Fig. 1: Cruise control diagnostic chart-1985-94 models



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Fig. Fig. 2: Cruise control diagnostic chart-1985-94 models



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Fig. Fig. 3: Cruise control diagnostic chart-1985-94 models



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Fig. Fig. 4: Cruise control diagnostic chart-1985-94 models



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Fig. Fig. 5: Cruise control diagnostic chart-1985-94 models



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Fig. Fig. 6: Cruise control diagnostic chart-1985-94 models



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Fig. Fig. 7: Cruise control diagnostic chart-1985-94 models



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Fig. Fig. 8: Cruise control diagnostic chart-1995-96 models



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Fig. Fig. 9: Cruise control diagnostic chart-1995-96 models



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Fig. Fig. 10: Cruise control diagnostic chart-1995-96 models



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Fig. Fig. 11: Cruise control wiring-1985-94 models



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Fig. Fig. 12: Cruise control wiring-1985-94 models



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Fig. Fig. 13: Cruise control wiring-1985-94 models



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Fig. Fig. 14: Cruise control wiring-1995-96 models

 
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