PRE-RELEASE
DTC B393B
| DTC B393B |
| 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 B393B 04
Air Conditioning Compressor Valve Control Circuit Open
DTC B393B 0B
Air Conditioning Compressor Valve Control Circuit High Current
| Circuit/System Description |
The HVAC control module supplies battery voltage to the A/C compressor. When the A/C switch is pressed, the HVAC control module provides a pulse width modulation (PWM) signal to the A/C compressor in order to command the performance of the A/C compressor. The performance of the A/C compressor is regulated according to adjusted interior temperature on the basis of characteristic performance data. Therefore the HVAC control module grounds the A/C compressor with the PWM signal.
| 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 |
B393B 04
A PWM greater than 10% is send out but no current is read back.B393B 0B
Measured current is above threshold of 815 mA.| Action Taken When the DTC Sets |
B393B 04
The A/C compressor is disabled.B393B 0B
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The A/C compressor is disabled.
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Output will be switched off for hardware protection.
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| 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 Q46 Air Conditioning Compressor Valve.
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| 2. |
Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 2 and ground.
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| 3. |
If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the FRT HVAC Fuse circuit open, test or replace the Q46 Air Conditioning Compressor Valve.
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| 4. |
Verify that a test lamp does not illuminate between the B+ circuit terminal 2 and the control circuit terminal 1.
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| 5. |
If the test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal, replace the K33 HVAC Control Module.
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| 6. |
Remove the test lamp.
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| 7. |
Command the A/C compressor ON with a scan tool. Verify the scan tool A/C Compressor Refrigerant Solenoid Valve Command parameter is 100%.
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| 8. |
If not the specified value, test the control circuit for a short to voltage. If the circuit tests normal, replace the K33 HVAC Control Module.
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| 9. |
If all circuits test normal, test or replace the Q46 Air Conditioning Compressor Valve.
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| Component Testing |
Static Test
| 1. |
Ignition OFF, disconnect the harness connector at the Q46 Air Conditioning Compressor Valve.
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| 2. |
Test for 7-15 Ω between B+ circuit terminal 2 and control circuit terminal 1.
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| 3. |
If not within the specified range, replace the Q46 Air Conditioning Compressor Valve.
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| 4. |
Test for infinite resistance between each terminal and the Q46 Air Conditioning Compressor Valve housing/case.
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| 5. |
If not the specified value, replace the Q46 Air Conditioning Compressor Valve.
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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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