Introduction
The B1679 Diagnostic Trouble Code (DTC) signifies a critical issue within a vehicle's security system. Specifically, it indicates a short circuit to the battery voltage in the alarm panic input circuit. This malfunction can lead to unintended alarm activations, a drained battery, and compromised vehicle security. Understanding the causes, symptoms, and diagnostic procedures associated with this code is essential for effective troubleshooting and repair.
Table: B1679 Alarm Panic Input Circuit Short To Battery - Comprehensive Information
| Category | Description | Potential Impact |
|---|---|---|
| Definition | The B1679 DTC indicates that the vehicle's computer (usually the Body Control Module or BCM) has detected an unintended voltage signal on the alarm panic input circuit, indicating a short to the positive (+) battery voltage. | Malfunctioning panic alarm system, potential for false alarms, battery drain, inoperable remote key fob functions related to the alarm, and potential damage to the BCM or related wiring. |
| Common Causes | - Damaged or frayed wiring harness near the panic button or within the steering column.\n- Shorted panic button switch.\n- Moisture intrusion into the panic button switch or wiring connectors.\n- Rodent damage to wiring.\n- Aftermarket alarm system installation errors.\n- Faulty BCM (less common). | Unreliable alarm system, repeated and unexpected alarm activations, inability to disarm the alarm, and increased risk of vehicle theft. |
| Symptoms | - Panic alarm activates intermittently without pressing the panic button.\n- Panic alarm won't deactivate.\n- Remote key fob panic button is inoperable.\n- Battery drain.\n- Check engine light might illuminate (depending on vehicle make/model).\n- Security light flashing or illuminated constantly. | Driver annoyance, potential for neighborhood disturbances due to false alarms, inconvenience of a dead battery, and reduced vehicle security. |
| Diagnostic Steps | 1. Visual Inspection: Inspect the panic button switch, wiring harness, and connectors for damage, corrosion, or moisture.\n2. Circuit Testing: Use a multimeter to check for voltage on the alarm panic input circuit with the panic button not pressed. Should read near zero volts. A reading close to battery voltage confirms the short.\n3. Component Testing: Disconnect the panic button switch and re-check the circuit voltage. If the short disappears, the switch is likely faulty.\n4. Wiring Harness Inspection: Carefully inspect the wiring harness for chafing, pinching, or rodent damage. Pay close attention to areas where the harness passes through the firewall or near moving parts.\n5. BCM Testing (Advanced): If the above steps don't identify the fault, a qualified technician may need to test the BCM for internal shorts or malfunctions. This often requires specialized diagnostic equipment. | Accurate identification of the root cause of the problem, preventing unnecessary component replacements, and ensuring a proper and lasting repair. |
| Possible Solutions | - Repair or replace damaged wiring.\n- Replace the faulty panic button switch.\n- Clean or replace corroded connectors.\n- Repair or replace the wiring harness.\n- Reprogram or replace the BCM (in rare cases).\n- Correct any errors in aftermarket alarm system installation. | Restoration of proper alarm system function, prevention of future problems, and enhanced vehicle security. |
| Tools Required | - Multimeter.\n- Wiring diagrams specific to the vehicle make and model.\n- Basic hand tools (screwdrivers, pliers, wire strippers).\n- Scan tool (to read and clear DTCs).\n- Circuit tester (optional). | Efficient and accurate diagnosis and repair of the problem. |
| Safety Precautions | - Disconnect the negative battery terminal before working on the electrical system.\n- Use proper grounding techniques when soldering.\n- Avoid working on the electrical system in wet conditions.\n- Consult the vehicle's service manual for specific safety instructions. | Prevention of electrical shock, damage to vehicle components, and personal injury. |
| Related DTCs | - B1678: Alarm Panic Input Circuit Short To Ground\n- B167A: Alarm Panic Input Circuit Open\n- Other DTCs related to the BCM or security system. | Comprehensive understanding of the alarm system and related issues. |
| Aftermarket Alarms | The presence of an aftermarket alarm system can complicate diagnosis. Improper installation or malfunctioning components in the aftermarket system can often cause the B1679 code. Disconnecting the aftermarket alarm system temporarily can help isolate the problem. | Pinpointing the source of the problem, especially when an aftermarket system is involved. |
| Location of Panic Button | The panic button is typically located on the key fob and/or on the dashboard or steering column of the vehicle. The exact location varies depending on the vehicle make and model. Consult the owner's manual for specific information. | Quick and easy access to the panic button and its associated wiring for inspection and testing. |
Detailed Explanations
Definition: The B1679 DTC specifically points to an electrical fault where the circuit responsible for triggering the panic alarm is receiving unintended battery voltage. This indicates a "short to battery," meaning the wire or component intended to be grounded (or at a low voltage) is instead connected directly to the vehicle's positive power source.
Common Causes: Several factors can contribute to a B1679 code. Damaged wiring, particularly near the panic button or within the steering column, is a frequent culprit. This damage can result from wear and tear, chafing against other components, or even rodent activity. A faulty panic button switch itself can also short internally, sending a false signal. Furthermore, moisture intrusion into the switch or wiring connectors can create a conductive path, leading to a short. Aftermarket alarm system installations, if not performed correctly, can also introduce shorts into the system. Finally, though less common, a malfunctioning BCM can be the source of the problem.
Symptoms: The most obvious symptom of a B1679 code is the panic alarm activating randomly without any input from the driver. The alarm might also be difficult or impossible to deactivate using the key fob or other means. A constant or intermittent battery drain is another common symptom, as the shorted circuit continuously draws power. In some vehicles, the check engine light may illuminate. The security light on the dashboard might also flash or remain constantly illuminated. The remote key fob panic button might become inoperable.
Diagnostic Steps: A systematic approach is crucial for diagnosing a B1679 code. Begin with a thorough visual inspection of the panic button switch, wiring harness, and connectors, looking for any signs of damage, corrosion, or moisture. Use a multimeter to check the voltage on the alarm panic input circuit. With the panic button not pressed, the reading should be close to zero volts. A reading near battery voltage confirms the short. Disconnect the panic button switch and re-check the circuit voltage. If the short disappears, the switch is likely faulty. Carefully inspect the wiring harness for chafing, pinching, or rodent damage, paying particular attention to areas where the harness passes through the firewall or near moving parts. If the above steps don't identify the fault, a qualified technician may need to test the BCM for internal shorts or malfunctions. This often requires specialized diagnostic equipment.
Possible Solutions: The solution to a B1679 code depends on the underlying cause. Repairing or replacing damaged wiring is often necessary. A faulty panic button switch should be replaced. Corroded connectors should be cleaned or replaced. If the wiring harness is severely damaged, it may need to be replaced. In rare cases, the BCM may need to be reprogrammed or replaced. If the problem stems from an aftermarket alarm system, correcting any installation errors is crucial.
Tools Required: Diagnosing and repairing a B1679 code requires a few essential tools. A multimeter is necessary for checking voltage and continuity. Wiring diagrams specific to the vehicle make and model are invaluable for tracing the circuit. Basic hand tools, such as screwdrivers, pliers, and wire strippers, are needed for accessing and working on the wiring and components. A scan tool can be used to read and clear DTCs. A circuit tester is an optional tool that can help identify shorts in the wiring.
Safety Precautions: When working on a vehicle's electrical system, safety should always be a top priority. Disconnect the negative battery terminal before starting any work. Use proper grounding techniques when soldering. Avoid working on the electrical system in wet conditions. Consult the vehicle's service manual for specific safety instructions.
Related DTCs: Understanding related DTCs can provide a more comprehensive picture of the problem. B1678 indicates an "Alarm Panic Input Circuit Short To Ground," while B167A indicates an "Alarm Panic Input Circuit Open." Other DTCs related to the BCM or security system may also be present and should be investigated.
Aftermarket Alarms: The presence of an aftermarket alarm system can significantly complicate the diagnostic process. Improper installation or malfunctioning components in the aftermarket system can often trigger the B1679 code. Temporarily disconnecting the aftermarket alarm system can help isolate the problem and determine if it is the source of the short.
Location of Panic Button: Knowing the location of the panic button is crucial for inspection and testing. The panic button is typically located on the key fob and/or on the dashboard or steering column of the vehicle. The exact location varies depending on the vehicle make and model. Consult the owner's manual for specific information.
Frequently Asked Questions
What does the B1679 code mean? It means the vehicle's computer has detected a short to battery voltage in the alarm panic input circuit. This can lead to false alarms and battery drain.
Can I fix the B1679 code myself? Potentially, if you have experience with automotive electrical systems and the necessary tools. However, professional diagnosis is often recommended.
Is the B1679 code serious? Yes, it can lead to a drained battery, false alarms, and a compromised security system. Prompt attention is advised.
How do I clear the B1679 code? Use a scan tool to clear the code after addressing the underlying problem. The code will return if the issue persists.
Will a B1679 code affect my car's performance? Not directly, but the drained battery and false alarms can be significant inconveniences.
Conclusion
The B1679 DTC indicates a short to battery voltage in the alarm panic input circuit, requiring careful diagnosis and repair. Addressing this issue promptly is essential for maintaining vehicle security and preventing further complications.