B0037 and B0038: How to Fix AUX Switch Problems DTC Codes

B0037 - AUX Switch Closed/Shorted to Ground: This code means that the AUX switch circuit is either closed or shorted to ground. This can prevent the AUX switch from working properly or cause it to activate the accessories unintentionally. B0038 - AUX Switch Open/Shorted to Battery: This code means that the AUX switch circuit is either open or shorted to the battery. This can prevent the AUX switch from working properly or cause it to drain the battery.

If your vehicle has an auxiliary (AUX) switch, you may use it to control various accessories in your vehicle, such as the power windows, power locks, and sunroof. However, sometimes the AUX switch may malfunction and cause some problems that trigger the diagnostic trouble codes (DTCs) B0037 and B0038. These codes indicate that there is something wrong with the AUX switch circuit. In this article, we will explain what these codes mean, what symptoms they cause, what causes them, how to diagnose them, and how to repair them.

What Do DTC Codes B0037 and B0038 Mean?

DTC codes B0037 and B0038 are related to the AUX switch circuit in your vehicle. The AUX switch circuit is a circuit that connects the AUX switch to the vehicle’s computer and other components. The AUX switch is a switch that is used to control various accessories in your vehicle, such as the power windows, power locks, and sunroof.

What Symptoms Do DTC Codes B0037 and B0038 Cause?

The symptoms of DTC codes B0037 and B0038 will vary depending on the make and model of your vehicle. However, some common symptoms include:

1. The AUX switch does not work.
2. The AUX switch works intermittently.
3. The AUX switch works when the vehicle is turned off.
4. The AUX switch causes the vehicle to stall or run poorly.

What Causes DTC Codes B0037 and B0038?

There are many possible causes of DTC codes B0037 and B0038, including:

• A faulty AUX switch
• A damaged or corroded AUX switch wiring harness
• A short circuit in the AUX switch wiring harness
• A problem with the AUX switch relay
• A problem with the vehicle’s electrical system

How to Diagnose DTC Codes B0037 and B0038?

To diagnose DTC codes B0037 and B0038, you will need a diagnostic scan tool to read the vehicle’s computer. You will also need a multimeter and a wiring diagram to test the AUX switch circuit for any faults.

1. The first step is to use the scan tool to retrieve the codes from your vehicle’s computer. You should also check if there are any other codes related to the AUX switch circuit or other systems in your vehicle.
2. The next step is to inspect the AUX switch circuit for any visible signs of damage, such as broken wires, loose connectors, corrosion, or burns. You should also check if the AUX switch is present and securely mounted.
3. The third step is to use the multimeter and the wiring diagram to test the continuity and resistance of the AUX switch circuit. You should also test if there is any voltage or current in this circuit that should not be there. You should compare your readings with the specifications in your vehicle’s manual.
4. The fourth step is to replace any faulty components, such as the AUX switch or the AUX switch relay, if they are found to be defective. You should also repair or replace any damaged wiring or connectors.

How to Repair DTC Codes B0037 and B0038?

The repair procedure for DTC codes B0037 and B0038 will depend on what caused them in the first place. If you have an open circuit in the AUX switch circuit, you will need to fix or replace the broken wire or connector. If you have a short circuit in the AUX switch circuit, you will need to identify and repair the source of the short circuit. If the AUX switch or the AUX switch relay is faulty, they will need to be replaced.

You should follow these steps to repair DTC codes B0037 and B0038:

• Disconnect the negative battery cable from your vehicle’s battery.
• Locate the AUX switch and the AUX switch relay in your vehicle. They are usually located under the dashboard or in the center console. Refer to your vehicle’s manual for the exact location and instructions on how to access them.
• Disconnect the electrical connectors from the AUX switch and the AUX switch relay. Be careful not to damage the wires or pins.
• Check for any signs of damage or wear on these components.
• Replace them with new ones if they are damaged or defective.
• Reconnect their electrical connectors securely.
• Reconnect your negative battery cable.
• Use your scan tool to clear any codes from your vehicle’s computer.
• Start your vehicle and check if the AUX switch is working properly and if the codes are gone.
• Test drive your vehicle and check for any other symptoms or codes related to the AUX switch circuit or other systems in your vehicle.

How to Prevent DTC Codes B0037 and B0038?

While there is no guarantee that you can prevent DTC codes B0037 and B0038 from happening again, there are some things you can do to reduce the chances of them occurring, such as:

• Avoid spilling liquids on the AUX switch.
• Keep the AUX switch clean and free of debris.
• Inspect the AUX switch circuit for damage or corrosion regularly.
• Have your vehicle’s electrical system inspected and serviced regularly by a qualified mechanic.

If you notice any of the symptoms of DTC codes B0037 or B0038, do not ignore them or delay getting them fixed. Have your vehicle diagnosed and repaired by a qualified mechanic as soon as possible to avoid further damage or injury.

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