Introduction:
The B1959 diagnostic trouble code (DTC) indicates a malfunction in the seat recline system, specifically an open circuit within the potentiometer feedback circuit used to monitor the seat's recline position. This code suggests the vehicle's computer (often the Body Control Module or Seat Control Module) is not receiving the expected signal from the potentiometer that tracks the seat's forward and backward movement. Resolving this issue is crucial for restoring full functionality of the power seat recline feature and ensuring accurate seat position memory (if equipped).
Comprehensive Table: B1959 Seat Recline Forward/Backward Potentiometer Feedback Circuit Open
| Aspect | Description | Possible Causes |
|---|---|---|
| Definition | Indicates an open circuit in the feedback circuit of the seat recline potentiometer. This circuit provides the seat control module (or BCM) with information about the seat's recline position. An open circuit means the signal is interrupted, preventing the module from accurately determining the seat's position. | 1. Faulty Potentiometer: The potentiometer itself may be damaged or worn, leading to an internal open circuit. 2. Wiring Issues: Broken, corroded, or disconnected wiring in the circuit connecting the potentiometer to the control module. This includes the signal wire, power wire, and ground wire. 3. Connector Problems: Corroded or loose connectors at the potentiometer or the control module can disrupt the circuit. 4. Module Failure: In rare cases, the seat control module or BCM itself may be faulty, preventing it from correctly interpreting or processing the potentiometer signal. 5. Fuse Issues: A blown fuse supplying power to the seat recline system. |
| Symptoms | 1. Seat Recline Inoperable: The seat may not recline forward or backward at all. 2. Intermittent Recline Function: The seat may recline intermittently or only in one direction. 3. Seat Position Memory Issues: If the vehicle has seat position memory, the memory function may not work correctly, or the seat may not return to the correct position. 4. Error Code Display: The B1959 code will be stored in the vehicle's computer and may trigger a warning light on the dashboard. 5. Unusual Noises: Grinding or clicking noises from the seat motor or mechanism may indicate a mechanical issue stressing the electrical components. |
Detailed Explanations:
1. Faulty Potentiometer:
A potentiometer is a three-terminal resistor with a sliding or rotating contact that forms an adjustable voltage divider. In the seat recline system, the potentiometer is mechanically linked to the seat's recline mechanism. As the seat reclines, the potentiometer's internal resistance changes. This change in resistance alters the voltage signal sent back to the control module, allowing it to determine the seat's precise position. If the potentiometer is damaged, worn, or has an internal open circuit, it won't be able to accurately reflect the seat's position. This can be verified by checking the potentiometer's resistance across its terminals with a multimeter. A smooth, consistent change in resistance as the seat reclines indicates a functional potentiometer. An erratic reading or no reading at all suggests a fault. Look for physical damage to the potentiometer housing, such as cracks or breaks, which can indicate internal damage.
2. Wiring Issues:
The wiring connecting the potentiometer to the control module is crucial for transmitting the position signal. An open circuit in any of these wires will interrupt the signal flow. Common causes of wiring problems include:
- Broken Wires: Wires can break due to repeated bending, chafing against other components, or damage from accidents. Carefully inspect the wiring harness for any visible breaks or cuts.
- Corroded Wires: Corrosion can build up on wire conductors, especially in areas exposed to moisture or road salt. This corrosion increases resistance and can eventually lead to an open circuit. Look for green or white deposits on the wires or connectors.
- Disconnected Wires: Wires can become disconnected from their terminals due to vibration or accidental dislodging. Ensure all wires are securely connected to the potentiometer and the control module.
Use a multimeter to perform a continuity test on each wire. Disconnect the wires from both ends (potentiometer and control module) and check for continuity between the two ends of each wire. No continuity indicates an open circuit. Use a wiring diagram specific to the vehicle to identify the correct wires and their connections.
3. Connector Problems:
Connectors provide a physical connection between the wires and the potentiometer or control module. Corrosion, loose connections, or damaged connector pins can disrupt the circuit. Inspect the connectors for the following:
- Corrosion: Clean any corrosion with a wire brush or electrical contact cleaner.
- Loose Connections: Ensure the connectors are securely plugged in and that the locking mechanism (if present) is engaged.
- Damaged Pins: Check for bent, broken, or pushed-out connector pins. Repair or replace damaged connectors as needed.
4. Module Failure:
While less common, the seat control module or Body Control Module (BCM) itself can fail. These modules are responsible for processing the signal from the potentiometer and controlling the seat motor. If the module's internal circuitry is damaged, it may not be able to correctly interpret the potentiometer signal, even if the potentiometer and wiring are functioning properly. This is often the last thing to suspect and requires careful diagnosis. Before suspecting a module failure, rule out all other possibilities. A scan tool capable of reading live data from the seat control module can help determine if the module is receiving the potentiometer signal and if it is outputting the correct commands to the seat motor.
5. Fuse Issues:
A blown fuse can interrupt the power supply to the seat recline system, causing the B1959 code. Locate the fuse for the seat recline system in the vehicle's fuse box (refer to the owner's manual or a wiring diagram). Inspect the fuse for any signs of damage, such as a broken filament. Replace the fuse with a new one of the correct amperage. If the fuse blows again immediately after replacement, it indicates a short circuit in the system that needs to be investigated further.
Possible Solutions:
- Inspect and Repair Wiring: Carefully examine all wiring associated with the seat recline system. Repair any broken, corroded, or disconnected wires.
- Clean or Replace Connectors: Clean corroded connectors with electrical contact cleaner. Replace any damaged connectors.
- Test and Replace Potentiometer: Test the potentiometer with a multimeter. If it is faulty, replace it with a new one.
- Check and Replace Fuses: Inspect the fuse for the seat recline system. Replace any blown fuses.
- Consult a Professional: If you are unable to diagnose and repair the problem yourself, consult a qualified automotive technician. They have the tools and expertise to properly diagnose and repair complex electrical problems.
- Module Replacement/Reprogramming: If, after careful diagnosis, the seat control module or BCM is determined to be faulty, it may need to be replaced. In some cases, the replacement module may need to be programmed or configured to the vehicle. This often requires specialized equipment and software.
Frequently Asked Questions:
- What does the B1959 code mean? It means there's an open circuit in the seat recline potentiometer feedback circuit, preventing the module from knowing the seat's position.
- Can I fix this problem myself? Possibly, if you have basic automotive repair skills and a multimeter. However, complex electrical issues might require a professional.
- How do I find the seat recline potentiometer? It's usually located near the seat recline motor, often attached to the recline mechanism itself. Consult a service manual for specific location details.
- How much does it cost to fix a B1959 code? The cost varies depending on the cause. A simple wiring repair might be inexpensive, while replacing the potentiometer or module can be more costly.
- Will this code affect other systems in my car? Generally, no. It primarily affects the seat recline function. However, if the seat also controls other safety features like airbags, it is best to get it fixed right away.
Conclusion:
The B1959 code indicates a problem with the seat recline potentiometer feedback circuit, most likely due to wiring, connector, or potentiometer issues. Thoroughly inspecting and testing these components is crucial for accurately diagnosing and resolving the problem, restoring the seat's recline functionality.