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Cruise Control Output Test (1991 Models)

  1. Run engine at idle for 2 minutes. Turn ignition off. Turn ignition to RUN position. Enter PCM diagnostics. Slide cruise control switch to ON position.
  2. Select PCM override ES07. Advance override until 99% is reached. Check cruise control servo position and operation. If servo pulls in slightly, check for at least 10 in. Hg of supply vacuum. Check vacuum hoses for leaks or restrictions. Check throttle cable for binding.
  3. If servo does not pull in at all, go to CRUISE CONTROL SERVO TEST. If servo pulls in completely, wait 30 seconds. Check that servo is still pulled in. If servo is not pulled in, check for a slow leak.
  4. Decrease override until zero percent is reached. Servo should be in released position. If servo is pulled in, check vacuum hoses for restrictions and servo throttle linkage for binding.
  5. If linkage and hoses are okay, replace servo. If servo is not pulled in, road test vehicle. If servo still does not work properly, replace PCM.
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