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Home >> Jeep >> 1990 >> Wrangler Laredo, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests - CARBURETED >> Knock Sensor Test >> Functional Test
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Functional Test

  1. Connect Diagnostic Readout Box II (DRB-II) diagnostic tester to vehicle and proceed to state display mode. Start engine and observe knock unit value.
  2. Using tip of screwdriver, gently tap cylinder block near knock sensor and observe knock value. Knock value should increase while tapping on cylinder block.
  3. If knock value does not increase while tapping on the cylinder block near knock sensor, check knock sensor for proper connection. If connection is good, replace knock sensor.