Air Conditioner Diagnostic Trouble Codes

• Code B0163 Front PCAT Sensor Input Voltage Short or Open Circuit
• Code B0163 Front PCAT Sensor Input Voltage Circuit Short to Ground or Open

• The HVAC controller detects that the air temperature setting is less than 0.27V or greater than 4.64V.
• The HVAC controller detects a short to battery positive in the in-car sensor or PCAT sensor circuit.
• The HVAC controller detects an open in-cabin or PCAT sensor control circuit.

• The fault code will be logged if the HVAC controller stops detecting a fault.
• Ignition in position "ON" or "OFF".
• The DTC can be cleared with a scan tool.

3. Checking the resistance of the interior sensor or PCAT sensor (2.2 kΩ at 25°C).
6. Checks voltage supplied to in-cabin sensor or PCAT sensor from HVAC controller (2.2 V at 25°C)

• Code B0173 Short to battery voltage or open circuit of airway sensor input voltage
• Code B0173 Duct Sensor Input Voltage Short to Ground or Open Circuit

• The HVAC controller detects that the air temperature setting is less than 0.27V or greater than 4.64V.
• The HVAC controller detects a short to battery positive in the duct sensor circuit.
• The HVAC controller detects an open duct sensor control circuit.

• The fault code will be logged if the HVAC controller stops detecting a fault.
• Ignition in position "ON" or "OFF".
• The DTC can be cleared with a scan tool.

6. Air duct sensor voltage is checked (2.2 V at 25°C).
7. Checking the resistance of the duct sensor (2.2 kΩ at 25°C)

• Code B0183 Short to battery voltage or open circuit of the front left solar radiation sensor.
• Code B0183 Short to ground or open circuit of the front left solar radiation sensor.

• The HVAC controller determines that the value of the solar sensor parameter is less than 0.20V or greater than 4.64V.
• The HVAC controller detects a short to battery positive in the solar sensor circuit.
• The HVAC controller detects an open in the solar sensor control circuit.

• The fault code will be logged if the HVAC controller stops detecting a fault.
• Ignition in position "ON" or "OFF".
• The DTC can be cleared with a scan tool.

9. The current strength at the output of the HVAC controller is checked. (In direct sunlight: 3.2 V, and in the shade: 4.0 V)

• Code B0193 Short to battery voltage or power module circuit open.
• Code B0193 Short to ground or open circuit of the power module.

• Electric fan operating voltage below 5.0V (actual fan feedback voltage), greater than 9.0V fan operating voltage.
• The operating voltage of the electric fan is higher than 9.0 V (actual fan feedback voltage), below 5.0V fan operating voltage.
• The HVAC controller detects an open or short in the electric fan control circuit.

• The fault code will be logged if the HVAC controller stops detecting a fault.
• Ignition in position "ON" or "OFF".
• The DTC can be cleared with a scan tool.

4. The voltage levels of the electric fan are checked, from the lowest to the highest level, and the voltage of all levels is increased by 0.5 V.

• Code B0228 Short to battery voltage or an open in the air intake damper feedback voltage circuit.
• Code B0228 Short to ground or open in the air intake damper feedback voltage circuit.
• Code B0228 The air intake damper feedback signal is invalid.

• Ignition in position "ON".

• The damper motor feedback voltage is below 0.20 V.
• The damper motor feedback voltage is greater than 4.8 V.
• The value of the position of the electric actuator of the intake flap corresponds to an unreachable position.

• The fault code will be logged if the HVAC controller stops detecting a fault.
• Ignition in position "ON" or "OFF".
• The DTC can be cleared with a scan tool.

1. Ignition switch in position "ON"
2. Check ignition voltage (12 V) and motor voltage (5 V) air intake damper actuator.
3. Check the air intake damper motor reference level.

• Code B0283 Electric heated rear window

• body controller (BCM) stores code B0283 in memory. The heated glass will not work.

• The current fault code is cleared after the fault disappears.
• The fault code is cleared from the log when the ignition cycle counter in the controller reaches the reset threshold without recurring the fault.

2. Check positive battery voltage at the coil side of the heated rear window relay. The coil side of the DEFOG relay is energized through fuse EF25 (10 A).
3. Test the DEFOG relay control circuit for faults that cause DTC B0283 to set.
4. Listen for a click when the DEFOG relay is activated. Issue a command to turn on and off. Repeat commands if necessary.
5. Check that the body controller (BCM) connected the glass heating relay to ground.

• Code B0413 Short to battery voltage or air mix damper feedback voltage circuit open.
• Code B0413 Air mixing damper feedback voltage short to ground or open circuit.
• Code B0413 Invalid air mix damper feedback signal.

• The feedback voltage of the air mixing damper motor is below 0.20 V.
• Air mix damper motor feedback voltage is greater than 4.8V.
• The position value of the air mixing damper motor corresponds to an unreachable position.

• The fault code will be logged if the HVAC controller stops detecting a fault.
• Ignition in position "ON" or "OFF".
• The DTC can be cleared with a scan tool.

2. Ignition switch in position "ON".
3. Ignition switch in position "ON".
4. Check ignition voltage (12 V) and motor voltage (5 V) air intake damper actuator.
5. Check the air intake damper motor reference level.

• Ignition switch in position "ON".

• The HVAC controller detects a bad ROM failure.

• The HVAC controller records operating conditions when a fault occurs during diagnostics. This information will be stored in buffers "Freeze" And "Fault records".
• A fault code is stored in the log.

• The fault code is cleared from the log after 40 consecutive warm-up cycles without a fault.
• Code (codes) Faults can be cleared with a diagnostic tool.
• Disconnect HVAC controller from battery power for 10 seconds

• Code B3779 Short to voltage or an open in the mode damper motor feedback voltage circuit.
• Code B3779 Short to ground or open circuit mode damper motor feedback voltage.
• Code B3779 Invalid mode damper motor feedback signal.

• Mode damper motor feedback voltage is below 0.20V.
• Mode damper motor feedback voltage is greater than 4.8V.
• The position value of the mode damper motor corresponds to an unreachable position.

• The fault code will be logged if the HVAC controller stops detecting a fault.
• Ignition in position "ON" or "OFF".
• The DTC can be cleared with a scan tool.

2. Ignition switch in position "ON".
3. Ignition switch in position "ON".
4. Check ignition voltage (12 V) and motor voltage (5 V) air intake damper actuator.
5. Check the air intake damper motor reference level.

• Code B3843 A short to battery voltage or an open in the outdoor air quality sensor input voltage circuit.
• Code B3843 A short to ground in the outdoor air quality sensor input voltage circuit.

• Ignition in position "ON".

• APS sensor feedback voltage is below 0.05V.
• APS sensor feedback voltage is greater than 4.79V.

• The APS sensor does not function.
• APS LED is off.

• The fault code will be logged if the HVAC controller stops detecting a fault.
• The DTC can be cleared with a scan tool.
• Disconnect HVAC controller from battery power for 10 seconds

2. The voltage of the APS sensor is checked. (In the range 0 - 5 V)
3. Ignition switch in position "ON", and the voltage at pin A16 and A9 of the HVAC controller connector is checked.

• The ignition is switched to position "ON".

• Segment lights up on HVAC controller "A/C OFF" ("air conditioning off").
• The air conditioner compressor turns off.

• The fault code will be logged if the HVAC controller stops detecting a fault.
• The fault code in the log will clear after 50 ignition cycles without a fault.
• The DTC can be cleared with a scan tool.

3. During this operation, the correct operation of the circuit in the upper voltage range is checked.
4. During this operation, the correct operation of the circuit in the lower voltage range is checked. If the jumper fuse blows during this test, there is a short to voltage in the signal circuit.

• Use the link list to identify low speed GMLAN serial link controllers.
• This test is used for a general data failure fault on a low speed GMLAN. If there is no communication with only 1 controller and no DTC is set, check that the vehicle is equipped with such a controller, and then run diagnostics for code U0100-U0299.
• GMLAN low speed serial link open circuit between terminal block and controller (controllers) will only affect a specific controller (controllers). This type of fault will cause a communication failure code to be set for each affected controller, while other controllers will still communicate.
• Opening terminal 5 of the DLC ground circuit will allow the scan tool to operate to tune the vehicle to the tool and then stop communicating with the vehicle. When the scan tool has essentially communicated with the vehicle, the scan tool will display the message "No CANdi module detected" (CANdi controller not found) and there will be no communication.
• Open circuit between the diagnostic connector (DLC) and connector C 203 will only affect communication with the diagnostic tool. The vehicle's controllers will still communicate and the vehicle will start.
• The engine will not start if a general low speed GMLAN serial link fault is present. The following conditions can contribute to the overall loss of communication on a low speed GMLAN link:
• Short to ground or open circuit in low speed GMLAN serial link.
• Internal controller failure that causes a short to voltage or ground on the low speed GMLAN line.
• Use the multimeter's MIN/MAX function to locate an intermittent fault.

1. Test for less than 1 ohm resistance between DLC ground circuit terminal 5 and ground.
• If resistance is greater than 1 ohm, test the ground circuit for an open or high resistance.
2. Ignition OFF, disconnect the harness connector at the SP 300 terminal block.
3. Ignition ON, scan tool attempt to communicate with instrument cluster (IPC). Communication must be available.
• If there is no communication, disconnect controllers that are still connected to the DLC connector one at a time, starting with the one farthest from the DLC, and try to establish communication after each disconnection. When communication is established, check the serial link for a short to ground and a short to voltage on the circuit between the last controller disconnected and the previous controller disconnected. If the circuit is OK, replace the last disconnected controller. If communication cannot be established, test the serial link for a short to ground, short to voltage, or an open/high resistance between the last disconnected controller and the DLC connector. If the circuit is OK, replace the last disconnected controller.
4. Install a jumper wire with a 3 amp fuse between pin A and pin M of the terminal block. Install another jumper with a 3 amp fuse on pin L.
5. Using the open end of the jumper on pin L, connect terminals B - K of the terminal block and attempt to communicate with each controller connected to the terminal block, one at a time. Each controller must be able to transmit data.
• If communication cannot be established with any controller after connecting a separate controller, replace the controller that caused the communication failure.

• Controller information for replacement, configuration, and programming.

1. The supply voltage of the controllers is within the normal operating range.
2. Vehicle power mode requires serial communication.

• The controller stops transmitting all commands.
• The controller uses standard values for all parameters received via serial communication lines.
• The controller inhibits the setting of all other DTCs.

• The current fault code is cleared after the fault disappears.
• The DTC is cleared from the log when the ignition cycle counter in the controller reaches the reset threshold of 50 cycles without a recurrence of the fault.

• The cause of the intermittent failure may be caused by a short in the high speed GMLAN links.
• This DTC cannot be received with current status.
• Symptom diagnostics in progress "The scan tool does not communicate with a device on a high speed GMLAN".
• Specific controllers using the high speed GMLAN link are listed in the link list.

1. The voltage in the system is 9 - 16 V.
2. Serial communication is required for the vehicle power mode master to operate.

• The current fault code is cleared after the fault disappears.
• The DTC is cleared from the log when the ignition cycle counter in the controller reaches the reset threshold of 50 cycles without a recurrence of the fault.

• Using the above list of DTC definitions, determine which of the controllers is out of communication.
• If there are several controllers with communication failure, select the one closest to the diagnostic socket (DLC).
• Use the link list to determine whether the GMLAN serial link on this controller is high speed or low speed.
• Some controllers lack internal protection for certain voltage outputs and may cause the battery positive voltage fuse or ignition voltage source to blow. If the input voltage fuse is blown but no short circuit is detected on this circuit, verify that the controllers do not have a voltage output circuit shorted to ground before replacing the controller.
• This diagnostic can be applied to any controller that needs to communicate over a high or low speed GMLAN serial link, provided the vehicle is equipped with the option that uses this controller.

1. Use the above list of DTC definitions and diagnostic tips to determine which controller is out of communication to check.
2. Ignition OFF, disconnect the harness connector at the controller that is not communicating.

Important: Only high speed GMLAN controllers have a serial line enable circuit OR an auxiliary serial line wakeup circuit. Refer to the controller diagrams to determine which controllers have these circuits. If the offending controller is missing one of these circuits, go to Step 4.

3. Ignition ON, verify the test lamp illuminates between the serial link enable circuit OR the serial link auxiliary wakeup circuit and ground.
• If the test lamp does not illuminate, repair the open or high resistance in the circuit. If there are no open circuits, replace the BCM.
• If the test lamp does not illuminate, repair the short to ground or open/high resistance in the circuit. If the circuit fuse is blown, also check the positive voltage outputs on the controller for a short to ground. If the circuits are OK, replace the failed controller.
• If the test lamp does not illuminate, repair the short to ground or open/high resistance in the circuit. If the circuit fuse is blown, also check the positive voltage outputs on the controller for a short to ground. If the circuits are OK, replace the failed controller.
• If it is greater than 1 ohm, repair the open in the ground circuit.
• If the controller only uses high speed GMLAN, replace the controller.
• If resistance is greater than 1 Ω, test the low speed GMLAN serial link circuit for an open or high resistance.

• Controller information for replacement, configuration, and programming.
• GMLAN wiring repair