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Home >> Cadillac >> 2018 >> Escalade Base, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 11 (Engine Controls And Fuel - 6.0L (L96) - DTC P0351 To DTC P2636 And Diagnostic Information And Procedures) >> Diagnostic Information And Procedures >> Electronic Ignition System Diagnosis >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2018 Chevrolet Suburban 3500 HD. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Do not perform this diagnostic procedure unless you were sent here from a misfire DTC or the Engine Cranks But Does Not Run diagnostic.
  1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the appropriate T8 Ignition Coil. It may take up to 2 min for all vehicle systems to power down.
  2. Test for less than 5 Ω between the ground circuit terminal A and ground.
    • If 5 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.
    • Go to next step: If less than 5 Ω 
  3. Test for less than 5 Ω between the low reference circuit terminal B and ground.
    • If 5 Ω or greater 
    1. Ignition OFF, disconnect the X2 harness connector at the K20 Engine Control Module.
    2. Test for less than 2 Ω in the low reference circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K20 Engine Control Module.
    • Go to next step: If less than 5 Ω 
  4. Ignition ON.
  5. Verify a test lamp illuminates between the ignition circuit terminal D and ground.
    • If the test lamp does not illuminate and the circuit fuse is good 
    1. Ignition OFF.
    2. Test for less than 2 Ω in the ignition circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.
    • If the test lamp does not illuminate and the circuit fuse is open 
      NOTE: The ignition circuit may supply voltage to other components. Make sure to test all circuits and components for a short to ground that share the ignition circuit.
    1. Ignition OFF, remove the test lamp, and disconnect all components on the circuit.
    2. Test for infinite resistance between the ignition circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. Replace the fuse, ignition ON.
    4. Verify the fuse is good after connecting each of the components one at a time.
      • If the fuse opens, replace the component that opens the fuse when connected.
      • If the fuse is good, all OK.
    • Go to next step: If the test lamp illuminates 
  6. Ignition OFF, exchange the suspect T8 Ignition Coil with the T8 Ignition Coil of a known functioning cylinder.
  7. Engine Running.
  8. Verify the scan tool Cylinder 1 - 8 Current Misfire Counter does not increment for the same cylinder that the suspect T8 Ignition Coil was removed from.
    • If increments 

      Replace the K20 Engine Control Module.

    • Go to next step: If does not increment 
  9. Test or replace the T8 Ignition Coil.
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