The B1799 diagnostic trouble code (DTC) indicates an open circuit in the front turn signal output circuit. This means the vehicle's computer (often the Body Control Module or BCM) has detected a break in the electrical pathway responsible for powering the front turn signal bulb. This malfunction prevents the turn signal from illuminating, creating a safety hazard and potentially resulting in a failed vehicle inspection.

This article will delve into the causes, diagnosis, and potential solutions for a B1799 code, providing a comprehensive guide for understanding and addressing this common automotive issue.

Topic Description Potential Impact
Definition of B1799 Diagnostic Trouble Code indicating an open circuit in the front turn signal output circuit. The vehicle's computer detects a break in the electrical path to the front turn signal bulb. Front turn signal lamp will not illuminate. This poses a safety risk by hindering the vehicle's ability to signal turns. May lead to a failed vehicle inspection.
Common Causes Burnt-out bulb: The most frequent cause. Damaged wiring: Broken, corroded, or frayed wires in the turn signal circuit. Loose or corroded connectors: Poor electrical contact at connectors in the circuit. Faulty turn signal switch: Internal failure within the switch. BCM (Body Control Module) failure: Less common, but a potential cause if the BCM is not properly sending the signal. Damaged bulb socket: Corrosion or physical damage to the bulb socket preventing proper contact. Intermittent or complete failure of the front turn signal. Difficulty in diagnosing the issue due to multiple potential causes. Potential for further electrical damage if left unresolved.
Symptoms Front turn signal not working: The primary symptom. Turn signal indicator flashing rapidly: Hyper-flashing often indicates a bulb issue or open circuit. No turn signal indicator on the dashboard: The dashboard indicator may not illuminate when the turn signal is activated. Error message on the dashboard: Some vehicles may display a specific error message related to the turn signal malfunction. Reduced visibility and increased risk of accidents. Driver confusion due to the lack of visual feedback from the turn signal system. Potential for legal repercussions if driving with a malfunctioning turn signal.
Diagnostic Steps 1. Visual Inspection: Check the bulb for burnout. Examine wiring and connectors for damage or corrosion. 2. Bulb Replacement: Replace the bulb with a known good one. 3. Voltage Test: Use a multimeter to check for voltage at the bulb socket when the turn signal is activated. 4. Continuity Test: Check the continuity of the wiring between the turn signal switch, BCM, and bulb socket. 5. Scan Tool Diagnosis: Use a scan tool to read DTCs and access BCM data. 6. Component Testing: Test the turn signal switch and BCM according to the manufacturer's specifications. Accurate identification of the root cause of the problem. Avoidance of unnecessary repairs. Efficient troubleshooting process.
Potential Solutions Replace the burnt-out bulb. Repair or replace damaged wiring. Clean or replace corroded connectors. Replace the faulty turn signal switch. Replace the damaged bulb socket. Reprogram or replace the BCM (as a last resort). Restoration of the front turn signal functionality. Improved vehicle safety. Compliance with traffic laws.
Related DTCs B1798: Lamp Turn Signal Front Output Circuit Short to Ground. B1797: Lamp Turn Signal Front Output Circuit Short to Battery. B1796: Lamp Turn Signal Front Output Circuit Low. B1800: Lamp Turn Signal Rear Output Circuit Open. Understanding of related electrical issues within the turn signal system. Comprehensive diagnosis and repair strategy.
Tools Required Multimeter: For voltage and continuity testing. Scan Tool: To read DTCs and access vehicle data. Wiring Diagram: To understand the turn signal circuit layout. Basic Hand Tools: Screwdrivers, pliers, wire strippers, etc. * Test Light: An alternative to a multimeter for basic voltage testing. Proper and safe execution of diagnostic and repair procedures. Efficient troubleshooting and problem-solving.
Safety Precautions Disconnect the battery: Before working on the electrical system to prevent shorts. Use appropriate safety gear: Wear safety glasses and gloves. Consult a wiring diagram: To avoid damaging other components. Be careful when working with electrical connectors: Avoid forcing connectors apart. * Properly insulate all wire splices: To prevent corrosion and short circuits. Prevention of electrical shock and further damage to the vehicle. Safe and effective repair process.

Detailed Explanations

Definition of B1799:

The B1799 DTC signifies that the vehicle's computer, typically the Body Control Module (BCM), has detected an open circuit in the electrical path that powers the front turn signal lamp. An "open circuit" means there is a break in the electrical pathway, preventing current from flowing to the bulb. This results in the turn signal failing to illuminate. The BCM monitors the current flow through the turn signal circuit, and when it detects an unexpectedly low or zero current, it sets the B1799 code.

Common Causes:

Several factors can lead to a B1799 code:

  • Burnt-out bulb: This is the most common culprit. Over time, the filament in the bulb can break, causing an open circuit.
  • Damaged wiring: Wires can become broken, corroded, or frayed due to age, exposure to the elements, or physical damage. This can create an open circuit in the turn signal system. Look for damaged insulation, kinks, or breaks in the wiring harness.
  • Loose or corroded connectors: Connectors in the turn signal circuit can become loose or corroded, preventing proper electrical contact. This can occur due to moisture, dirt, or vibration.
  • Faulty turn signal switch: The turn signal switch controls the flow of electricity to the turn signal lamps. If the switch is faulty, it may not properly close the circuit, resulting in an open circuit.
  • BCM (Body Control Module) failure: Although less common, a malfunctioning BCM can incorrectly interpret the circuit or fail to send the proper signal to the turn signal. This is usually diagnosed after ruling out other potential causes.
  • Damaged bulb socket: The bulb socket itself can become corroded or physically damaged, preventing proper contact between the bulb and the electrical circuit.

Symptoms:

The most obvious symptom of a B1799 code is a non-functional front turn signal lamp. However, other symptoms may also be present:

  • Front turn signal not working: This is the primary and most noticeable symptom.
  • Turn signal indicator flashing rapidly: "Hyper-flashing" or rapid blinking of the turn signal indicator on the dashboard often indicates a bulb issue or an open circuit in the turn signal system.
  • No turn signal indicator on the dashboard: In some cases, the dashboard indicator may not illuminate at all when the turn signal is activated, indicating a problem with the circuit.
  • Error message on the dashboard: Some vehicles equipped with advanced diagnostic systems may display a specific error message related to the turn signal malfunction.

Diagnostic Steps:

Diagnosing a B1799 code involves a systematic approach:

  1. Visual Inspection: Begin by visually inspecting the bulb for burnout. Also, carefully examine the wiring and connectors in the turn signal circuit for any signs of damage or corrosion.
  2. Bulb Replacement: Replace the bulb with a known good one to rule out a simple bulb failure.
  3. Voltage Test: Use a multimeter to check for voltage at the bulb socket when the turn signal is activated. If there is no voltage, it indicates an open circuit upstream.
  4. Continuity Test: Perform a continuity test on the wiring between the turn signal switch, BCM, and bulb socket. This will help identify any breaks in the wiring.
  5. Scan Tool Diagnosis: Use a scan tool to read DTCs and access BCM data. This can provide valuable information about the circuit's status.
  6. Component Testing: Test the turn signal switch and BCM according to the manufacturer's specifications. This will help determine if these components are functioning correctly. Refer to a service manual for proper testing procedures.

Potential Solutions:

The solution to a B1799 code depends on the underlying cause:

  • Replace the burnt-out bulb: If the bulb is burnt out, replacing it will resolve the issue.
  • Repair or replace damaged wiring: Repair any damaged wiring by splicing in new sections or replacing the entire wire harness if necessary.
  • Clean or replace corroded connectors: Clean corroded connectors with a wire brush or contact cleaner. If the corrosion is severe, replace the connector.
  • Replace the faulty turn signal switch: If the turn signal switch is faulty, replace it with a new one.
  • Replace the damaged bulb socket: If the bulb socket is damaged, replace it to ensure proper electrical contact.
  • Reprogram or replace the BCM (as a last resort): If the BCM is faulty, it may need to be reprogrammed or replaced. This should only be done after all other potential causes have been ruled out.

Related DTCs:

Understanding related DTCs can help with a more comprehensive diagnosis:

  • B1798: Lamp Turn Signal Front Output Circuit Short to Ground. This indicates that the circuit is shorted to ground, causing excessive current flow.
  • B1797: Lamp Turn Signal Front Output Circuit Short to Battery. This indicates that the circuit is shorted to the battery voltage, causing excessive current flow.
  • B1796: Lamp Turn Signal Front Output Circuit Low. This indicates that the voltage in the circuit is lower than expected.
  • B1800: Lamp Turn Signal Rear Output Circuit Open. This indicates an open circuit in the rear turn signal output circuit.

Tools Required:

Having the right tools is essential for diagnosing and repairing a B1799 code:

  • Multimeter: A multimeter is essential for testing voltage and continuity in the electrical circuit.
  • Scan Tool: A scan tool is needed to read DTCs and access vehicle data.
  • Wiring Diagram: A wiring diagram is crucial for understanding the turn signal circuit layout.
  • Basic Hand Tools: Screwdrivers, pliers, wire strippers, and other basic hand tools are necessary for disassembly and repair.
  • Test Light: A test light can be used as an alternative to a multimeter for basic voltage testing.

Safety Precautions:

Always follow safety precautions when working on the electrical system:

  • Disconnect the battery: Disconnect the negative battery terminal before working on the electrical system to prevent shorts and electrical shock.
  • Use appropriate safety gear: Wear safety glasses and gloves to protect yourself from injury.
  • Consult a wiring diagram: Refer to a wiring diagram to avoid damaging other components.
  • Be careful when working with electrical connectors: Avoid forcing connectors apart, as this can damage them.
  • Properly insulate all wire splices: Use heat shrink tubing or electrical tape to properly insulate all wire splices to prevent corrosion and short circuits.

Frequently Asked Questions

What does the B1799 code mean? The B1799 code means there's an open circuit in the front turn signal output circuit, preventing the turn signal from working. It indicates a break in the electrical pathway to the front turn signal bulb.

What is the most common cause of a B1799 code? The most common cause is a burnt-out turn signal bulb. Check and replace the bulb first before investigating other potential causes.

Can I fix a B1799 code myself? Yes, if you have basic automotive knowledge and the right tools, you can diagnose and fix a B1799 code. Start with simple checks like the bulb and wiring, and consult a service manual for your vehicle.

Is it dangerous to drive with a B1799 code? Yes, driving with a non-functional turn signal is dangerous as it impairs your ability to signal turns, increasing the risk of accidents. It is also illegal in most jurisdictions.

Will a B1799 code cause my car to fail inspection? Yes, most vehicle inspections require all lights, including turn signals, to be functional. A B1799 code will likely cause your car to fail.

Conclusion

The B1799 DTC indicates a problem with the front turn signal output circuit, typically an open circuit preventing the lamp from illuminating. Thorough diagnosis, starting with simple checks and progressing to more complex component testing, is essential to identify and resolve the root cause, ensuring safe and compliant vehicle operation.