PRE-RELEASE
DTC B3843
| DTC B3843 |
| Diagnostic Instructions |
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Perform the
Diagnostic System Check - Vehicle
prior to using this diagnostic procedure.
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Review
Strategy Based Diagnosis
for an overview of the diagnostic approach.
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Diagnostic Procedure Instructions
provides an overview of each diagnostic category.
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| DTC Descriptor |
DTC B3843 02
Outside Air Quality Sensor Circuit Short to Ground
DTC B3843 05
Outside Air Quality Sensor Circuit High Voltage/Open
DTC B3843 08
Outside Air Quality Sensor Circuit Performance - Signal Invalid
| 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 door while in the automatic mode as soon as the concentration of pollutants exceeds a preset value.
| Conditions for Running the DTC |
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Ignition ON.
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The HVAC control module is ON.
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| 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
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Circuit Testing
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Connector Repairs
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Testing for Intermittent Conditions and Poor Connections
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Wiring Repairs
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Scan Tool Reference
Control Module References for scan tool information
| Circuit/System Testing |
| 1. |
Ignition OFF, disconnect the harness connector at the B108 Air Quality Sensor.
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| 2. |
Test for less than 10 Ω between the ground circuit terminal 2 and ground.
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| 3. |
If greater than the specified range, test the ground circuit for an open/high resistance. If the circuit tests normal, replace the K33 HVAC Control Module.
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Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 1 and ground.
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| 5. |
If the test lamp does not illuminate, test the ignition circuit for a short to ground or a open/high resistance. If the circuit tests normal, replace the K33 HVAC Control Module.
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Verify the scan tool Odor Sensor parameter is greater than 95%.
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| 7. |
If less than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the K33 HVAC Control Module.
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| 8. |
Install a 3 A fused jumper wire between the following signal circuit terminal 3 and the ground circuit terminal 2. Verify the scan tool Odor Sensor parameter is less than 5%.
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| 9. |
If greater than the specified range, test the signal circuit for a short to voltage or open/high resistance. If the circuit tests normal, replace the K33 HVAC Control Module.
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| 10. |
If all circuits test normal, replace the B108 Air Quality Sensor.
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| Repair Instructions |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
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HVAC Component Replacement Reference
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Control Module References
for HVAC Control Module replacement, setup, and programming
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