Circuit/System Testing

2019 Chevrolet Tahoe LS, 4WD, Gas/EthanolSECTION Circuit/System Testing
WARNING: This page is about a different car, the 2018 Chevrolet Sonic. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the X5 harness connector at the K9 Body Control Module, ignition ON.
  2. Verify a test lamp illuminates between the control circuit terminal 13 and ground.
    • If the test lamp does not illuminate 
    1. Ignition OFF, disconnect the X2 harness connector at the X50A Fuse Block - Underhood.
    2. Test for infinite resistance between the control circuit terminal and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: 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 X50A Fuse Block - Underhood.
    • Go to next step: If the test lamp illuminates 
  3. Ignition OFF, connect a 3 A fused jumper between the control circuit terminal 13 and ground.
  4. Remove the front fog lamp fuse at the X50A Fuse Block - Underhood, ignition ON.
  5. Verify a test lamp illuminates between the front fog lamp fuse B+ switch control terminal and ground.
    • If the test lamp does not illuminate 
    1. Ignition OFF, disconnect the X2 harness connector at the X50A Fuse Block - Underhood, ignition ON.
    2. Test for less than 1 V between the control circuit terminal 13 and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the X50A Fuse Block - Underhood.
    • Go to next step: If the test lamp illuminates 
  6. Test or replace the K9 Body Control Module.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.