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Home >> Jeep >> 1999 >> Cherokee Classic, 2.5 P >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Self-Diagnostic Tests >> NTC-3B: Checking ECM Power & Ground Circuits

NTC-3B: Checking ECM Power & Ground Circuits

  1. Turn ignition off. Disconnect ECM connector. Clean and/or repair connector as necessary. Using a 12-volt test light connected to ground, probe both ECM connector, B+ circuits. For wire color, see WIRING DIAGRAMS article. If test light illuminates brightly on both circuits, go to next step. If test light does not illuminate brightly, repair open B+ circuit(s).
  2. Ensure ignition is off. Ensure ECM connector is still disconnected. Turn ignition on, with engine off. Using 12-volt test light connected to ground, probe ECM connector, fused ignition switch output circuit. For wire color, see WIRING DIAGRAMS article. If test light illuminates brightly, go to next step. If test light does not illuminate brightly, repair open fused ignition switch output circuit. 3) Turn ignition off. Ensure ECM connector is still disconnected. Using 12-volt test light connected to ground, probe both ECM connector, ground circuits. For wire color, see WIRING DIAGRAMS article. If test light illuminates brightly on both circuits, go to next step. If test light does not illuminate brightly on both circuits, repair open ground circuit(s).
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