Introduction:
The B1551 diagnostic trouble code (DTC) indicates a malfunction in the deck lid (trunk) release circuit of a vehicle. This circuit is responsible for electronically opening the trunk, usually via a button on the key fob, a switch inside the car, or a touch sensor on the trunk itself. A B1551 code suggests the vehicle's computer has detected an electrical fault, preventing the trunk from opening as intended. Addressing this issue promptly is important for convenience and security.
Table: B1551 Deck lid Release Circuit Failure Details
| Component/Area | Description | Possible Causes/Symptoms |
|---|---|---|
| Deck Lid Release Solenoid/Actuator | The electromechanical device that physically unlocks the trunk latch. It receives a signal from the vehicle's body control module (BCM) or equivalent computer. | - Trunk will not open electronically. - Clicking or buzzing sound from the trunk area but no release. - Solenoid physically damaged or corroded. - Solenoid winding is open or shorted. |
| Wiring Harness & Connectors | The electrical wires and connectors that carry the signal and power to the deck lid release solenoid. These are vulnerable to damage from wear, tear, and environmental factors. | - Intermittent trunk release operation. - Trunk release works sometimes, but not always. - Visible damage to wiring (cuts, frays, corrosion). - Loose or corroded connectors. - Short to ground or open circuit in the wiring. - Increased resistance in the circuit due to corrosion. |
| Deck Lid Release Switch (Interior/Key Fob) | The switches that send the signal to activate the deck lid release. The interior switch is typically located inside the car, while the key fob switch transmits a radio frequency signal. | - Trunk release does not work from the interior switch. - Trunk release does not work from the key fob. - Switch physically damaged or stuck. - Faulty switch contacts. - Key fob battery low or dead. - Key fob needs reprogramming. |
| Body Control Module (BCM) or Equivalent Computer | The central computer that controls various body functions, including the deck lid release. It receives input from the switches and sends the signal to the solenoid. | - Multiple electrical malfunctions throughout the vehicle. - Inability to control other electronic features. - BCM is faulty or needs reprogramming. - BCM receives incorrect input signals. - BCM driver circuit for the trunk release is damaged. |
| Trunk Latch Mechanism | The physical latch that secures the trunk lid. A faulty latch can prevent the solenoid from properly releasing the trunk. | - Trunk latch is binding or sticking. - Trunk latch is misaligned. - Trunk latch cable is damaged or stretched (if applicable). - Trunk latch is corroded or dirty. - Difficult to manually open the trunk even after the solenoid attempts to release it. |
| Fuses and Relays | Fuses protect circuits from overcurrent, and relays act as electrically controlled switches. A blown fuse or faulty relay can disable the deck lid release circuit. | - Trunk release is completely inoperative. - Other electrical components on the same circuit may also be affected. - Blown fuse is visible upon inspection. - Relay is clicking but not activating. - Relay is not receiving power or ground. |
| Ground Connections | A secure ground connection is essential for proper circuit operation. A loose or corroded ground can cause intermittent or complete circuit failure. | - Intermittent trunk release operation. - Other electrical malfunctions in the vehicle. - Visible corrosion or looseness at ground connections. - Increased resistance in the ground circuit. |
| Battery Voltage | Insufficient battery voltage can prevent the solenoid from operating correctly. | - Weak or dead battery. - Trunk release works intermittently or weakly. - Other electrical components may also be affected. - Low voltage reading at the deck lid release solenoid. |
| Aftermarket Accessories | Improperly installed aftermarket accessories (e.g., alarms, remote starters) can interfere with the deck lid release circuit. | - Trunk release stopped working after the installation of an aftermarket accessory. - Wiring modifications have damaged the original circuit. - Aftermarket accessory is drawing excessive current. |
| Diagnostic Tools and Procedures | Proper diagnostic tools (e.g., multimeter, scan tool) and procedures are necessary to accurately diagnose the B1551 code. | - Inability to accurately diagnose the cause of the problem. - Incorrect repairs are performed, leading to further problems. - Misinterpretation of diagnostic data. |
Detailed Explanations:
Deck Lid Release Solenoid/Actuator: This component is the heart of the electronic trunk release. When energized, it moves a lever or cable that unlatches the trunk. A faulty solenoid can be due to internal electrical failure (open or short circuit), mechanical binding, or corrosion. Symptoms include a non-responsive trunk, a clicking sound without release, or physical damage to the solenoid itself. Testing the solenoid involves checking its resistance with a multimeter and verifying that it receives power when the release button is pressed.
Wiring Harness & Connectors: The wiring harness and connectors are the pathways for electrical signals. They are susceptible to damage from physical stress, vibration, moisture, and heat. Inspecting the wiring for cuts, frays, and corrosion is crucial. Connectors should be checked for loose connections and corrosion. A multimeter can be used to test for continuity and voltage at various points in the circuit. Pay close attention to wiring that passes through hinges or areas prone to flexing.
Deck Lid Release Switch (Interior/Key Fob): These switches initiate the trunk release process. A faulty switch can prevent the signal from reaching the BCM. Testing the interior switch involves using a multimeter to check for continuity when the switch is pressed. Key fob issues can stem from a dead battery, damage to the fob itself, or the need for reprogramming. Verify the key fob battery is good. If that doesn't work, try reprogramming the key fob following the vehicle's owner's manual instructions.
Body Control Module (BCM) or Equivalent Computer: The BCM is a central control unit that manages various vehicle functions, including the trunk release. A faulty BCM can cause a range of electrical problems. Diagnosing a BCM issue often requires specialized diagnostic equipment and expertise. Symptoms include multiple electrical malfunctions, inability to control other electronic features, and the presence of other DTCs. Sometimes, a simple reprogramming of the BCM can resolve the issue, but in other cases, replacement may be necessary.
Trunk Latch Mechanism: Even with a functioning solenoid, a binding or misaligned trunk latch can prevent the trunk from opening. Inspect the latch for proper alignment, lubrication, and freedom of movement. Check for any obstructions or damage that might be hindering its operation. If a cable is involved, ensure it is properly adjusted and not stretched or broken.
Fuses and Relays: Fuses protect electrical circuits from overcurrent, and relays act as electrically controlled switches. A blown fuse or faulty relay can disable the trunk release circuit. Check the fuse box for any blown fuses associated with the trunk release. Replace any blown fuses with the correct amperage rating. If the fuse blows again immediately, it indicates a short circuit in the system. Test the relay by swapping it with a known good relay or using a multimeter to check its functionality.
Ground Connections: A good ground connection is essential for proper circuit operation. A loose or corroded ground can cause intermittent or complete circuit failure. Locate all ground connections related to the trunk release circuit and inspect them for corrosion or looseness. Clean and tighten any suspect ground connections. Use a multimeter to check the resistance between the ground connection and the vehicle's chassis.
Battery Voltage: Insufficient battery voltage can prevent the solenoid from operating correctly. Ensure the battery is properly charged and in good condition. Test the battery voltage with a multimeter. A low voltage reading can indicate a weak battery or a charging system problem.
Aftermarket Accessories: Improperly installed aftermarket accessories can interfere with the deck lid release circuit. Disconnect any aftermarket accessories that may be affecting the trunk release circuit to see if the problem resolves. Inspect the wiring modifications made during the installation of the aftermarket accessory for any damage or improper connections.
Diagnostic Tools and Procedures: Accurate diagnosis requires proper tools and procedures. A multimeter is essential for testing voltage, continuity, and resistance. A scan tool can read DTCs and provide valuable diagnostic information. Follow the vehicle manufacturer's recommended diagnostic procedures for the B1551 code.
Frequently Asked Questions:
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What does the B1551 code mean? It indicates a fault in the deck lid (trunk) release circuit, meaning the car's computer has detected an electrical problem. This prevents the trunk from opening electronically.
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Can I fix the B1551 code myself? Depending on your mechanical skills and access to tools, you might be able to troubleshoot and fix simple issues like blown fuses or loose connections. Complex problems may require a professional technician.
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How much does it cost to fix a B1551 code? The cost varies depending on the cause and the repair needed. Simple fixes like replacing a fuse might be inexpensive, while replacing the BCM could be costly. Expect to pay for diagnostic labor in addition to the repair.
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What are the most common causes of the B1551 code? Common causes include a faulty deck lid release solenoid, damaged wiring, a faulty switch, a blown fuse, or a problem with the BCM.
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Will a B1551 code affect other vehicle systems? While primarily affecting the trunk release, a BCM issue could potentially impact other electrical systems.
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Is it safe to drive with a B1551 code? Generally, yes. The B1551 code usually doesn't affect the vehicle's drivability or safety, but it's recommended to address the issue for convenience and security.
Conclusion:
The B1551 deck lid release circuit failure can be caused by a variety of factors, ranging from simple problems like blown fuses to more complex issues like a faulty BCM. By systematically investigating the components of the circuit, most owners can pinpoint and resolve the issue, restoring the function of their trunk release. It is always recommended to consult a qualified technician if you are unsure about the diagnosis or repair procedures.