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Home >> GMC >> 1987 >> Forward Control 7.4 W, Standard >> Repair and Diagnosis >> Transmission >> Automatic Trans >> Servicing - A/T >> Adjustments >> Transmission Vacuum Regulator Valve >> With Electrical Control

With Electrical Control

  1. Loosely assemble throttle position switch to fuel injection pump with throttle lever in closed position. Attach an ohmmeter across terminals IGN (Pink wire) and EGR (Yellow wire).
  2. Insert "switch-closed" .624" (15.8 mm) Gauge Bar for Emission Label Code YJH or .646" (16.4 mm) Gauge Bar (J-33043) for all other models, between gauge boss on pump and wide open stop screw on throttle shaft. Rotate and hold throttle lever against gauge block.
  3. Rotate throttle switch clockwise (facing throttle switch) until continuity occurs (high meter reading) across terminals. Hold switch body at this position and tighten mounting bolts to 4-5 ft. lbs. (5-7 N.m).
    NOTE: Switch point must be set only while rotating switch body in clockwise direction.
  4. Release throttle lever and allow it to return to idle position. Remove "switch-closed" gauge bar and insert "switch-open" .646" (16.4 mm) Gauge Bar (J-33043) for Emission Label Code (YJH) or .668" (16.9 mm) Gauge Bar for all other models. If no continuity exists, switch is set properly. If continuity exists, switch must be reset or replaced.
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