B3933
DTC B3933
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC B3933 02
- Air Conditioning Evaporator Temperature Sensor Circuit Short to Ground
DTC B3933 05
- Air Conditioning Evaporator Temperature Sensor Circuit High Voltage/Open
Diagnostic Fault Information
Circuit/System Description
The temperature sensors are a 2-wire negative temperature co-efficient thermistor. A signal circuit and low reference circuit is provided to the sensor. As the air temperature surrounding the sensor increases, the sensor resistance decreases. The sensor signal voltage decreases as the resistance decreases. The sensor operates within a temperature range between -40 to 85°C (-40 to 185°F).
Conditions for Running the DTC
* Ignition ON.
* The HVAC control module is ON.
Conditions for Setting the DTC
The HVAC control module detects the sensor signal voltage is less than 0.1 V or greater than 4.9 V for more than 50 ms.
Action Taken When the DTC Sets
The A/C compressor is disabled if the last test is not passed.
Conditions for Clearing the DTC
The sensor signal is within specified range between 0.1-4.9 V.
Reference Information
Schematic Reference
HVAC Schematics Electrical Diagrams
Connector End View Reference
Component Connector End Views Fuel Pump and Level Sensor Assembly
Description and Operation
Manual HVAC Description and Operation HVAC - Manual
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Verification
1. Ignition ON.
2. Verify the scan tool A/C Evaporator Temperature Sensor parameter is within 5°C (9°F) of the actual evaporator temperature.
• If not within 5°C (9°F)
Refer to Circuit/System Testing
• If within 5°C (9°F)
3. All OK.
Circuit/System Testing
1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the B39 A/C evaporator temperature sensor It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 20 ohms between the low reference circuit terminal B and ground.
• If 20 ohms or greater
1. Ignition OFF, disconnect the harness connector at the K33 HVAC control module.
2. Test for less than 2 ohms in the low reference circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K33 HVAC control module control module.
• If less than 20 ohms
3. Ignition ON.
4. Verify the scan tool A/C Evaporator Temperature Sensor parameter is less than -37°C (-31°F).
• If -37°C (-31°F) or greater
1. Ignition OFF, disconnect the harness connector at the K33 HVAC control module.
2. Test for infinite resistance between the signal circuit terminal A 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 less than -37°C (-31°F)
5. Install a 3 A fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B.
6. Verify the scan tool A/C Evaporator Temperature Sensor parameter is greater than 82°C (180°F).
• If 82°C (180°F) or less
1. Ignition OFF, disconnect the harness connector at the 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
3. Ignition OFF
4. Test for less than 2 ohms in the signal circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K33 HVAC control module.
• If greater than 82°C (180°F)
7. Test or replace the B39 evaporator temperature sensor.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Evaporator Air Temperature Sensor Replacement (LHD) Service and Repair
* Control Module References Control Module References for HVAC control module replacement, programming, and setup