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Home >> Chevrolet >> 2015 >> Cruze LT, Automatic Trans >> Repair and Diagnosis >> External Pages >> Different car >> Section 18 (Wiring Systems And Power Management - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC B144B: Run/Crank Power Relay >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2015 Chevrolet Trax and 2015 Buick Encore. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the KR73 Ignition Main Relay (underhood) and the KR73 Ignition Main Relay (rear body), ignition ON.
  2. Test for less than 10 Ω between the ground circuits listed below and ground.
    • KR73 Ignition Main Relay (underhood) - Ground circuit terminal 85
    • KR73 Ignition Main Relay (rear body) - Ground circuit terminal 2
    • If 10 Ω or greater 
    1. Ignition OFF.
    2. Test for less than 2 Ω in the ground circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, repair the open/high resistance in the ground connection.
    • If less than 10 Ω 
  3. Ignition ON, connect a test lamp between the control circuits listed below and ground.
    • KR73 Ignition Main Relay (underhood) - Control circuit terminal 86
    • KR73 Ignition Main Relay (rear body) - Control circuit terminal 1
  4. Verify the test lamp turns ON and OFF when commanding the Run/Crank relay On and Off with a scan tool.
    • If the test lamp is always OFF 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module.
    2. Test for infinite resistance between the control circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. Test for less than 2 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K9 Body Control Module.
    • If the test lamp is always ON 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module, ignition ON.
    2. Test for less than 1 V between the control circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K9 Body Control Module.
    • If the test lamp turns ON and OFF 
  5. Test or replace the KR73 Ignition Main Relay (underhood) or the KR73 Ignition Main Relay (rear body).
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