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Home >> Cadillac >> 2015 >> SRX Base, 4D Utility >> Repair and Diagnosis (Single Page) >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> HVAC System - Automatic >> Diagnostic Information and Procedures >> DTC B018A, B048C, B048F, or B1395: Windshield Temperature Sensor/Humidity Sensor/Module Reference >> Circuit/System Testing
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Circuit/System Testing

  1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the B160 Windshield Temperature and Inside Moisture Sensor. It may take up to 10 min for all vehicle systems to power down.
    2. NOTE:

    The scan tool must be disconnected from the vehicle before performing the next test.

  2. Test for less than 10 Ω between the low reference circuit terminal 3 and ground.
    • If 10 Ω or greater 
    1. Ignition OFF, disconnect the harness connectors at the K33 HVAC 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 K33 HVAC Control Module.
    • If less than 10 Ω 
  3. Ignition ON.
  4. Test for 4.8-5.2 V between the 5 V reference circuit terminal 1 and ground.
    • If less than 4.8 V 
    1. Ignition OFF, disconnect the harness connectors at the K33 HVAC Control Module.
    2. Test for infinite resistance between the 5 V reference 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 5 V 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 K33 HVAC Control Module.
    • If greater than 5.2 V 
    1. Ignition OFF, disconnect the harness connectors at the K33 HVAC Control Module, ignition ON.
    2. Test for less than 1 V between the 5 V reference 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.
    • If between 4.8-5.2 V 
  5. Verify the scan tool parameters listed below are less than -37°C (-35°F).
    • Windshield Temperature
    • Passenger Compartment Humidity Sensor Temperature
    • If -37°C (-35°F) or greater 
    1. Ignition OFF, disconnect the harness connectors at the K33 HVAC Control Module.
    2. Test for infinite resistance between the signal circuit terminals listed below and ground:
      • Windshield temperature sensor signal terminal 4
      • Passenger compartment humidity sensor temperature signal terminal 5
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the K33 HVAC Control Module.
    • If less than -37°C (-35°F) 
  6. Test for 4.8-5.2 V between the signal circuit terminals listed below and ground.
    • Windshield temperature sensor signal terminal 4
    • Passenger compartment humidity sensor temperature signal terminal 5
    • If less than 4.8 V 
    1. Ignition OFF, disconnect the harness connector at the K33 HVAC Control Module.
    2. Test for infinite resistance between the signal 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 signal 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 greater than for 5.2 V 
    1. Ignition OFF, disconnect the harness connector at the K33 HVAC Control Module, ignition ON.
    2. Test for less than 1 V between the signal 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.
    • If between 4.8-5.2 V 
  7. Install a 3 A fused jumper wire between the low reference circuit terminal 3 and each signal circuit terminal listed below:
    • Windshield temperature sensor signal terminal 4
    • Passenger compartment humidity sensor temperature signal terminal 5
  8. Verify the appropriate scan tool parameter listed below is greater than 114°C (238°F).
    • Windshield Temperature
    • Passenger Compartment Humidity Sensor Temperature
    • If 114°C (238°F) or less 
    1. Ignition OFF, remove the jumper wire and disconnect the harness connectors at the K33 HVAC Control Module, ignition ON.
    2. Test for less than 1 V between the signal circuit terminals listed below and ground:
      • Windshield temperature sensor signal terminal 4
      • Passenger compartment humidity sensor temperature signal terminal 5
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V
    3. Test for less than 2 Ω in the signal 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 greater than 114°C (238°F) 
  9. Remove the jumper wire.
  10. Verify the scan tool Passenger Compartment Humidity parameter is greater than 95%.
    • If 95% or less 
    1. Ignition OFF, disconnect the harness connectors at the K33 HVAC Control Module, ignition ON.
    2. Test for infinite resistance between the signal circuit terminal 2 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the K33 HVAC Control Module.
    • If greater than 95% 
  11. Test for 4.8-5.2 V between the signal circuit terminal 2 and ground.
    • If less than 4.8 V 
    1. Ignition OFF, disconnect the harness connector at the K33 HVAC Control Module.
    2. Test for infinite resistance between the signal 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 signal 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 greater than for 5.2 V 
    1. Ignition OFF, disconnect the harness connector at the K33 HVAC Control Module, ignition ON.
    2. Test for less than 1 V between the signal 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.
    • If between 4.8-5.2 V 
  12. Install a 3 A fused jumper wire between the passenger compartment humidity signal circuit terminal 2 and the low reference circuit terminal 3.
  13. Verify the scan tool Passenger Compartment Humidity Sensor parameter is less than 5%.
    • If 5% or greater 
    1. Ignition OFF, remove the jumper wire and disconnect the harness connectors at the K33 HVAC Control Module, ignition ON.
    2. Test for less than 1 V between the signal circuit terminal 2 and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V
    3. Test for less than 2 Ω in the signal 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 less than 5% 
  14. Test or replace the B160 Windshield Temperature and Inside Moisture Sensor.
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