B1803 – OBD-II DTC

OBD-II DTC B1803 – Lamp Turn Signal Rear Output Circuit Open

DTC B1803 meaning

DTC B1803 refers to a diagnostic trouble code indicating an open circuit in the rear turn signal output circuit. This code is part of the On-Board Diagnostics II (OBD-II) system, which monitors various vehicle components and systems for faults. When the vehicle’s control module detects that the rear turn signal circuit is not functioning correctly, it triggers this code to alert the technician of a potential issue.

DTC B1803 symptoms

Common symptoms associated with DTC B1803 may include:

• Inoperative rear turn signals
• Illuminated warning lights on the dashboard
• Flashing turn signal indicator at an abnormal rate
• Possible malfunction of other related lighting systems

DTC B1803 causes

Several factors can lead to the occurrence of DTC B1803, including:

• Broken or damaged wiring in the turn signal circuit
• Faulty turn signal bulbs
• Corroded or loose electrical connections
• Defective turn signal relay or module
• Issues with the vehicle’s body control module (BCM)

DTC B1803 seriousness

DTC B1803 is considered a moderate to serious issue, primarily because it affects the vehicle’s turn signal functionality. This can lead to safety concerns, as other drivers may not be aware of the driver’s intentions to turn or change lanes. It is essential to address this code promptly to ensure safe operation of the vehicle.

How to diagnose DTC B1803

To diagnose DTC B1803, follow these steps:

1. Use an OBD-II scanner to confirm the presence of the B1803 code.
2. Inspect the rear turn signal bulbs for any signs of damage or failure.
3. Check the wiring and connectors in the turn signal circuit for breaks, corrosion, or loose connections.
4. Test the turn signal relay and body control module for proper operation.
5. Perform continuity tests on the circuit to identify any open connections.

How to fix DTC B1803 step-by-step instructions

To fix DTC B1803, follow these step-by-step instructions:

1. Replace any faulty rear turn signal bulbs.
2. Repair or replace damaged wiring and connectors in the turn signal circuit.
3. Clean any corroded connections to ensure good electrical contact.
4. Replace the turn signal relay if it is found to be defective.
5. Reprogram or replace the body control module if necessary.
6. Clear the DTC using an OBD-II scanner and test the turn signals to ensure proper operation.

How to erase DTC B1803

To erase DTC B1803, follow these steps:

1. Connect an OBD-II scanner to the vehicle’s diagnostic port.
2. Turn on the vehicle’s ignition without starting the engine.
3. Navigate to the “Erase Codes” or “Clear DTCs” option on the scanner.
4. Confirm the action to clear the trouble codes.
5. Disconnect the scanner and start the vehicle to verify that the code does not reappear.

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