To the top of the document
Orlando
   
GMDE Start Page Load static TOC Load dynamic TOC Help?

DTC B3843

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    • Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC B3843 02: Air Quality Sensor Circuit Short to Ground

DTC B3843 05: Air Quality Sensor Circuit High Voltage/Open

DTC B3843 08: Air Quality Sensor Circuit Performance - Signal Invalid

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Air Quality Sensor Ignition

-

B3843 05

--

--

Air Quality Sensor Signal

B3843 02

B3843 05

B3843 05

B3843 08

Air Quality Sensor Ground

-

B3843 05

--

--

Circuit/System Description

The HVAC control module detects exhaust gas by an air quality sensor. The air quality sensor is a 3-wire sensor with an ignition voltage circuit, a ground circuit and a signal circuit.

The information is pulse width modulation (PWM) signal generated on the output pin.

The HVAC control module evaluates the information of the air quality sensor and closes the recirculation flap while in the automatic mode, as soon as the concentration of pollutants exceeds a preset value.

Conditions for Running the DTC

    • Ignition ON.
    • The HVAC control module is ON.

Conditions for Setting the DTC

B3843 02

No PWM is detected and the signal is low.

B3843 05

No PWM is detected and the signal is high.

B3843 08

The Sensor sends a 5% PWM signal indicating an internal sensor short circuit or open circuit.

Action Taken When the DTC Sets

The automatic recirculation mode is disabled.

Conditions for Clearing the DTC

The condition for setting the DTC is no longer present.

Reference Information

Schematic Reference

HVAC Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Automatic HVAC Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

  1. Verify that DTC B3843 08 is not set.
  2. [ARW-LISTFAIL]
  3. If DTC B3843 08 is present

    Replace the B108 Air Quality Sensor.

  4. [/ARW-LISTFAIL][ARW-LISTPASS]
  5. If DTC B3843 08 is not present

  6. [/ARW-LISTPASS]
  7. Verify that DTC B3843 02 or B3843 05 is not set.
  8. [ARW-LISTFAIL]
  9. If DTC B3843 02 or B3843 05 is present

    Refer to Circuit/System Testing.

  10. [/ARW-LISTFAIL][ARW-LISTPASS]
  11. If DTC B3843 02 and B3843 05 are not present

  12. [/ARW-LISTPASS]
  13. All OK.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the B108 Air Quality Sensor.
  2. Test for less than 5 Ω between the ground circuit terminal 2 and ground.
  3. [ARW-LISTFAIL]
  4. If greater than 5 Ω

    Repair the open/high resistance in the circuit.

  5. [/ARW-LISTFAIL][ARW-LISTPASS]
  6. If less than 5 Ω

  7. [/ARW-LISTPASS]
  8. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 1 and ground.
  9. [ARW-LISTFAIL]
  10. If the test lamp does not illuminate and the circuit fuse is good

  11. [/ARW-LISTFAIL]
    3.1. Ignition OFF.
    3.2. Test for less than 2 Ω in the ignition circuit end to end.
    [ARW-LISTFAIL]
  12. If 2 Ω or greater, repair the open/high resistance in the circuit.

  13. If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.

  14. [/ARW-LISTFAIL] [ARW-LISTFAIL]
  15. If the test lamp does not illuminate and the circuit fuse is open

  16. [/ARW-LISTFAIL]
    3.1. Ignition OFF.
    3.2. Test for infinite resistance between the ignition circuit and ground.
    [ARW-LISTFAIL]
  17. If less than infinite resistance, repair the short to ground on the circuit.

  18. [/ARW-LISTFAIL][ARW-LISTFAIL]
  19. If infinite resistance, replace the B108 Air Quality Sensor.

  20. [/ARW-LISTFAIL] [ARW-LISTPASS]
  21. If the test lamp illuminates

  22. [/ARW-LISTPASS]
  23. Verify the scan tool Air Quality Sensor parameter is greater than 95%.
  24. [ARW-LISTFAIL]
  25. If less than 95%

  26. [/ARW-LISTFAIL]
    4.1. Ignition OFF, disconnect the X1 harness connector at the K33 HVAC Control Module.
    4.2. Ignition ON, test for infinite resistance between the signal circuit terminal 3 and ground.
    [ARW-LISTFAIL]
  27. If less than infinite resistance, repair the short to ground on the circuit.

  28. [/ARW-LISTFAIL][ARW-LISTFAIL]
  29. If infinite resistance, replace the K33 HVAC Control Module.

  30. [/ARW-LISTFAIL] [ARW-LISTPASS]
  31. If greater than 95%

  32. [/ARW-LISTPASS]
  33. Install a 3 A fused jumper wire between the signal circuit terminal 3 and the ground circuit terminal 2. Verify the scan tool Air Quality Sensor parameter is less than 5%.
  34. [ARW-LISTFAIL]
  35. If greater than 5%

  36. [/ARW-LISTFAIL]
    5.1. Ignition OFF, disconnect the X1 harness connector at the K33 HVAC Control Module.
    5.2. Ignition ON, test for less than 0.3 V between the signal circuit and ground.
    [ARW-LISTFAIL]
  37. If greater than 0.3 V, repair the short to voltage on the circuit.

  38. [/ARW-LISTFAIL][ARW-LISTPASS]
  39. If less than 0.3 V

  40. [/ARW-LISTPASS]
    5.3. Ignition OFF, test for less than 2 Ω in the signal circuit end to end.
    [ARW-LISTFAIL]
  41. If 2 Ω or greater, repair the open/high resistance in the circuit.

  42. If less than 2 Ω, replace the K33 HVAC Control Module

  43. [/ARW-LISTFAIL] [ARW-LISTPASS]
  44. If less than 5%

  45. [/ARW-LISTPASS]
  46. Replace the B108 Air Quality Sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Ambient Air Quality Sensor Replacement
    • Control Module References for HVAC control module replacement, setup, and programming
   


© Copyright Chevrolet. All rights reserved