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DTC B393B

DTC B393B

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 B393B 04

Air Conditioning Compressor Valve Control Circuit Open

DTC B393B 0B

Air Conditioning Compressor Valve Control Circuit High Current

Diagnostic Fault Information

Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performance
A/C Compressor B+

B393B 04

B393B 04

-

-

A/C Compressor Control

B393B 04

B393B 04

B393B 0B

1

1. A/C Compressor Malfunction



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 lines. Therefore the HVAC control module grounds the A/C compressor with the PWM signal.

Conditions for Running the DTC


• Ignition ON.

• The HVAC control module is ON.


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

• The A/C compressor is disabled.

• Output will be switched off for hardware protection.


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 Testing


1. Ignition OFF, disconnect the harness connector at the Q46 Air Conditioning Compressor Valve.

2. Ignition ON, test for greater than 11 V between the B+ circuit terminal B and ground.

3. If less than the specified range, test the B+ circuit for a short to ground or an open/high resistance.

4. Ignition OFF, disconnect the X2 harness connector at the K33 HVAC Control Module.

5. Ignition ON, test for less than 0.3 V between the control circuit terminal 10 X2 and ground.

6. If greater than the specified range, test the control circuit for a short to voltage.

7. Ignition OFF, test for infinite resistance between the control circuit terminal 10 X2 and ground.

8. If less than the specified range, test the control circuit for a short to ground.

9. Test for less than 5 Ω between the Q46 Air Conditioning Compressor Valve control circuit terminal A and control circuit terminal 10 X2 at the K33 HVAC Control Module harness connector

10. If greater than the specified value, test the control circuit for an open/high resistance.

11. If all circuits test normal, test or replace the Q46 Air Conditioning Compressor Valve and verify the DTC does not reset.

12. If the DTC resets, replace the K33 HVAC Control Module.


Component Testing


Static Test

1. Ignition OFF, disconnect the harness connector at the Q46 Air Conditioning Compressor Valve.

2. Test for 7-15 Ω between control circuit terminal A and B+ circuit terminal B.

3. If not within the specified range, replace the Q46 Air Conditioning Compressor Valve.

4. Test for infinite resistance between each terminal and the Q46 Air Conditioning Compressor Valve housing/case.

5. If not the specified value, replace the Q46 Air Conditioning Compressor Valve.


Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.


• Air Conditioning Compressor Replacement (LBS/A20DTH) Air Conditioning Compressor Replacement (LAU/A28NER) Air Conditioning Compressor Replacement (LLU/A16LET) Air Conditioning Compressor Replacement (LBY/A20DTR) Air Conditioning Compressor Replacement (LHU/A20NFT)

• Control Module References for HVAC control module replacement, setup, and programming