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Home >> Cadillac >> 2018 >> Escalade Base, 4WD >> Repair and Diagnosis >> Body & Frame >> Windows >> Fixed And MOVEABLE Window System >> Diagnostic Information And Procedures >> DTC B0283: Rear Defrost Circuit >> Circuit/System Testing
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Circuit/System Testing

  1. Ignition OFF, disconnect the KR5 Rear Defogger Relay
  2. Disconnect the KR4B Outside Rear View Mirror Heater Relay.
  3. Connect a test lamp between the control circuit terminal 65 and the ground circuit terminal 60 at the KR5 Rear Defogger Relay, Engine Running.
  4. Verify the test lamp turns ON and OFF commanding the Rear Defogger Command 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 K33 HVAC 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 K33 HVAC Control Module.
    • If the test lamp is always ON 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K33 HVAC Control Module, Engine Running.
    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 K33 HVAC Control Module.
    • Go to next step: If the test lamp turns ON and OFF 
  5. Test or replace the KR5 Rear Defogger Relay or the KR4B Outside Rear View Mirror Heater Relay.
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