B1804 – OBD-II DTC

OBD-II DTC B1804 – Lamp Turn Signal Rear Output Circuit Short To Battery

DTC B1804 meaning

DTC B1804 refers to a diagnostic trouble code indicating a short circuit in the rear turn signal output circuit, specifically a short to battery. 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 voltage in the rear turn signal circuit is higher than expected, it triggers this code.

DTC B1804 symptoms

Common symptoms associated with DTC B1804 may include:

• Inoperative rear turn signals
• Illuminated warning lights on the dashboard
• Flashing turn signal indicators that may behave erratically
• Possible malfunction of other related lighting systems

DTC B1804 causes

Several factors can lead to the triggering of DTC B1804, including:

• Wiring issues such as frayed or damaged wires
• Corroded connectors in the turn signal circuit
• Faulty turn signal relay or module
• Short circuits caused by aftermarket modifications or repairs
• Defective bulbs or sockets

DTC B1804 seriousness

DTC B1804 is considered a moderate to serious issue. While it may not immediately affect the vehicle’s drivability, it poses a safety risk due to the potential failure of turn signals, which are crucial for safe driving and communication with other road users. It is advisable to address this code promptly to ensure proper vehicle operation and safety.

How to diagnose DTC B1804

To diagnose DTC B1804, follow these steps:

1. Use an OBD-II scanner to confirm the presence of the B1804 code.
2. Inspect the rear turn signal circuit wiring for visible damage or wear.
3. Check the connectors for corrosion or loose connections.
4. Test the turn signal bulbs and sockets for proper operation.
5. Examine the turn signal relay or module for faults.
6. Perform a continuity test on the circuit to identify any shorts to battery.

How to fix DTC B1804 step-by-step instructions

To fix DTC B1804, follow these step-by-step instructions:

1. Disconnect the vehicle’s battery to ensure safety while working on the electrical system.
2. Inspect and repair any damaged wiring in the rear turn signal circuit.
3. Clean or replace corroded connectors as necessary.
4. Replace any faulty turn signal bulbs or sockets.
5. Test the turn signal relay or module and replace it if found defective.
6. Reconnect the battery and clear the DTC using an OBD-II scanner.
7. Test the turn signals to ensure they are functioning correctly.

How to erase DTC B1804

To erase DTC B1804, 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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