Introduction:

The diagnostic trouble code (DTC) B1560, "Door Lock Cylinder Circuit Open," indicates an electrical fault within the door lock system. This code signifies that the vehicle's computer (typically the Body Control Module or BCM) has detected an interruption or complete break in the electrical circuit responsible for sensing the position of the door lock cylinder. Resolving this issue is crucial for proper door locking functionality, security, and preventing potential vehicle malfunctions.

Table: B1560 Door Lock Cylinder Circuit Open

Category Description Possible Causes
Definition Door Lock Cylinder Circuit Open: The vehicle's computer has detected an open circuit in the electrical system monitoring the door lock cylinder position. 1. Damaged or disconnected wiring to the door lock cylinder position sensor.
2. Faulty door lock cylinder position sensor.
3. Corroded or loose electrical connectors.
4. Open circuit in the wiring harness.
5. Faulty Body Control Module (BCM).
6. Blown fuse (less common, but possible).
Symptoms 1. Door lock not responding to key insertion.
2. Keyless entry system malfunctioning.
3. Alarm system behaving erratically.
4. Security light illuminated.
5. Inability to lock or unlock the door with the key.
6. Diagnostic Trouble Code (DTC) B1560 present.		 -
Troubleshooting 1. Visual inspection of wiring and connectors.
2. Testing the door lock cylinder position sensor.
3. Checking for continuity in the wiring harness.
4. Examining the BCM for damage.
5. Using a scan tool to verify the DTC and monitor sensor data.
6. Checking relevant fuses.		 -

Detailed Explanations

Definition: Door Lock Cylinder Circuit Open

This DTC, B1560, signifies that the vehicle's computer, usually the Body Control Module (BCM), has registered an "open circuit" within the system responsible for monitoring the position of the door lock cylinder. An open circuit means there is a break in the electrical pathway, preventing the signal from the door lock cylinder sensor from reaching the BCM. This interruption disrupts the BCM's ability to accurately determine the lock's position, leading to various malfunctions.

Symptoms

  • Door lock not responding to key insertion: The most obvious symptom is that the door lock might not engage or disengage when the key is inserted and turned in the lock cylinder.

  • Keyless entry system malfunctioning: The remote key fob might not lock or unlock the door, or the system might behave unpredictably.

  • Alarm system behaving erratically: The car alarm could trigger randomly or fail to arm/disarm correctly. This is because the system may not be able to properly determine the door's locked/unlocked state.

  • Security light illuminated: The vehicle's security system warning light on the dashboard might stay illuminated, indicating a problem with the security system.

  • Inability to lock or unlock the door with the key: Even using the physical key, you may not be able to lock or unlock the affected door.

  • Diagnostic Trouble Code (DTC) B1560 present: This code will be stored in the vehicle's computer and can be retrieved using an OBD-II scan tool.

Possible Causes

  • Damaged or disconnected wiring to the door lock cylinder position sensor: This is one of the most frequent causes. Wires can become frayed, broken, or disconnected due to wear and tear, especially within the door jamb area where they flex with door movement.

  • Faulty door lock cylinder position sensor: The sensor itself, which is responsible for detecting the lock cylinder's position and sending a signal to the BCM, could be defective. This sensor may have failed internally.

  • Corroded or loose electrical connectors: Corrosion can build up on electrical connectors, especially in areas exposed to moisture. Loose connectors can also interrupt the electrical circuit.

  • Open circuit in the wiring harness: A break in the wiring harness, caused by damage or wear, can prevent the signal from reaching the BCM. This can be due to physical damage to the harness, rodent damage, or even chafing against sharp edges inside the door.

  • Faulty Body Control Module (BCM): Although less common, the BCM itself could be the source of the problem. Internal failures within the BCM can prevent it from correctly interpreting the signal from the door lock cylinder sensor.

  • Blown fuse (less common, but possible): While not the primary cause, a blown fuse in the circuit powering the door lock system could contribute to the problem. Always check relevant fuses as a first step in troubleshooting.

Troubleshooting

  • Visual inspection of wiring and connectors: Carefully examine the wiring and connectors associated with the door lock cylinder. Look for any signs of damage, corrosion, or loose connections. Pay close attention to areas where the wiring flexes, such as the door jamb.

  • Testing the door lock cylinder position sensor: Use a multimeter to test the sensor's resistance and voltage output. Consult the vehicle's repair manual for the correct testing procedures and specifications. You will need to disconnect the sensor and use the multimeter to measure resistance, voltage, and continuity based on the manufacturer's specifications for the sensor.

  • Checking for continuity in the wiring harness: Use a multimeter to check for continuity in the wiring harness between the door lock cylinder sensor and the BCM. This will help you identify any breaks or shorts in the wiring. Disconnect the battery before performing this test to prevent damage to the electrical system.

  • Examining the BCM for damage: Visually inspect the BCM for any signs of damage, such as burnt components or water intrusion. If you suspect the BCM is faulty, it may need to be tested or replaced.

  • Using a scan tool to verify the DTC and monitor sensor data: Connect an OBD-II scan tool to the vehicle's diagnostic port and verify that the B1560 code is present. The scan tool can also be used to monitor the sensor data and see if the door lock cylinder position sensor is sending a signal to the BCM.

  • Checking relevant fuses: Locate the fuse box(es) and inspect the fuses associated with the door lock system. Replace any blown fuses with the correct amperage rating.

How to Diagnose a B1560 Code (Step-by-Step)

  1. Retrieve the DTC: Use an OBD-II scanner to confirm the presence of the B1560 code. Note any other related codes that may be present.

  2. Visual Inspection: Carefully inspect the wiring and connectors associated with the door lock cylinder. Look for signs of damage, corrosion, or loose connections. Pay particular attention to the wiring harness in the door jamb.

  3. Fuse Check: Check the fuses related to the door lock system. Replace any blown fuses with the correct amperage.

  4. Sensor Testing: Disconnect the door lock cylinder position sensor. Use a multimeter to test the sensor's resistance and voltage output. Compare your readings to the vehicle manufacturer's specifications.

  5. Wiring Continuity Test: With the battery disconnected, use a multimeter to perform a continuity test on the wiring between the door lock cylinder sensor and the BCM. This will help you identify any open circuits or shorts in the wiring.

  6. BCM Inspection: Visually inspect the BCM for any signs of damage, such as burnt components or water intrusion.

  7. Component Replacement (if necessary): Based on your testing, replace any faulty components, such as the door lock cylinder sensor or the BCM.

  8. Clear the DTC: After making any repairs, clear the DTC using the OBD-II scanner.

  9. Test the System: Test the door lock system to ensure that it is functioning properly.

Tools Needed for Diagnosis and Repair

  • OBD-II Scanner: To retrieve and clear diagnostic trouble codes.
  • Multimeter: To test electrical circuits, sensors, and wiring.
  • Wiring Diagram: To understand the electrical connections in the door lock system. Crucial for accurate testing and repair.
  • Basic Hand Tools: Screwdrivers, pliers, wire strippers, etc.
  • Electrical Contact Cleaner: To clean corroded connectors.
  • Test Light: A simple tool to quickly check for power and ground in circuits.
  • Wiring Repair Kit: To repair damaged wiring.

Frequently Asked Questions

What does the B1560 code mean? It indicates an open circuit in the door lock cylinder position sensor circuit, meaning the vehicle's computer isn't receiving a signal from the sensor. This can cause various door lock and security system issues.

Can I fix the B1560 code myself? Yes, if you have basic automotive knowledge, tools, and access to a wiring diagram. However, professional diagnosis is recommended if you're not comfortable working with electrical systems.

Is it safe to drive with a B1560 code? It's generally safe to drive, but the door lock and security system may not function correctly. This could compromise the vehicle's security.

How much does it cost to fix a B1560 code? The cost varies depending on the cause. A simple wiring repair might be inexpensive, while replacing the BCM can be costly.

What is the door lock cylinder position sensor? It's a sensor that detects the position of the key cylinder (locked, unlocked, or in between) and sends this information to the vehicle's computer. It's located near the door lock cylinder.

Conclusion

The B1560 "Door Lock Cylinder Circuit Open" code points to an electrical problem within the door lock system. Careful diagnosis involving visual inspection, sensor testing, and wiring checks is essential to pinpoint the root cause and restore proper door locking functionality. If you are uncomfortable performing these diagnostic steps, it is recommended to seek assistance from a qualified automotive technician.