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Home >> Cadillac >> 2020 >> XT6 Sport >> Repair and Diagnosis >> External Pages >> Different car >> Section 35 (Automatic Level Control System) >> Diagnostic Information and Procedures >> DTC C14D4 >> Circuit/System Testing
July 1: So it begins. Don't worry, this is not in the correct legal jurisdiction!

Circuit/System Testing

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2020 GMC Yukon XL, 2020 GMC Yukon, 2020 Chevrolet Tahoe, 2020 Chevrolet Suburban, and 2020 Cadillac Escalade ESV. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the KR99 Air Suspension Relay, ignition ON.
  2. Verify a test lamp illuminates between the B+ circuit terminal 30 circuit terminal and ground.
    • If the test lamp does not illuminate and the circuit fuse is good 
    1. Ignition OFF, remove the test lamp.
    2. Test for less than 2 Ω in the B+ 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 
    1. Ignition OFF, remove the test lamp.
    2. Test for infinite resistance between the B+ circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: If infinite resistance,
    3. Disconnect the G3 Air Suspension Compressor.
    4. Test for infinite resistance between the control circuit terminal 87 and ground.
      • If less than infinite resistance repair the short to ground on the circuit.
      • If infinite resistance, test or replace the G3 Air Suspension Compressor.
    • Go to next step: If the test lamp illuminates 
  3. Verify a test lamp illuminates between the ignition circuit terminal 86 and ground.
    • If the test lamp does not illuminate and the circuit fuse is good 
    1. Ignition OFF, remove the test lamp.
    2. Test for less than 2 Ω in the ignition circuit end to end.
    • If the test lamp does not illuminate and the circuit fuse is open 
    1. Ignition OFF, remove the test lamp.
    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, test or replace the KR99 Air Suspension Relay.
    • Go to next step: If the test lamp illuminates 
  4. Connect a test lamp between the ignition circuit terminal 86 and the control circuit terminal 85.
  5. Verify the test lamp turns ON and OFF when commanding the KR99 Air Suspension Relay On and Off with a scan tool.
    • If the test lamp is always OFF 
    1. Ignition OFF, disconnect the harness connector at the K38 Chassis 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.
      • Go to next step: If less than 1 V
    3. Ignition OFF.
    4. 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 K38 Chassis Control Module.
    • If the test lamp is always ON 
    1. Ignition OFF, disconnect the harness connector at the K38 Chassis 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, replace the K38 Chassis Control Module
    • Go to next step: If the test lamp turns ON and OFF 
  6. Verify a test lamp does not illuminate between the control circuit terminal 87 and ground.
    • If the test lamp illuminates 

      Repair the short to voltage on the circuit.

    • Go to next step: If the test lamp does not illuminate 
  7. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the G3 Air Suspension Compressor. It may take up to 2 min for all vehicle systems to power down.
  8. Test for less than 10 Ω between the G3 Air Suspension Compressor ground circuit terminal G and ground.
    • 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.
    • Go to next step: If less than 10 Ω 
  9. Connect the harness connector at the G3 Air Suspension Compressor.
  10. Ignition ON, connect a 30 A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87.
  11. Verify the G3 Air Suspension Compressor is activated.
    • If the G3 Air Suspension Compressor does not activate 
    1. Ignition OFF, remove the jumper wire.
    2. Test for less than 2 Ω in the control circuit terminal 87 end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, test or replace the G3 Air Suspension Compressor.
    • Go to next step: If the G3 Air Suspension Compressor activates 
  12. Test or replace the KR99 Air Suspension Relay.
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