Introduction:
The B1958 diagnostic trouble code (DTC) indicates a fault within the seat recline forward/backward potentiometer feedback circuit. This circuit is crucial for the proper functioning of power seats, allowing the seat control module to accurately determine the seat's recline position. A failure in this circuit can lead to various issues, including the inability to adjust the seat recline, erratic seat movement, or even complete seat immobilization. Addressing this DTC promptly is essential for both comfort and safety.
Table: B1958 Seat Recline Forward/Backward Potentiometer Feedback Circuit Failure - Details and Troubleshooting
| Topic | Description | Possible Causes |
|---|---|---|
| Potentiometer Function | The potentiometer acts as a variable resistor, providing a voltage signal to the seat control module that corresponds to the seat's recline angle. As the seat reclines, the resistance changes, altering the voltage signal. This allows the module to track the seat's position. | Worn Potentiometer: Physical wear and tear on the potentiometer's internal components can lead to inaccurate readings or complete failure. Contamination: Dirt, debris, or corrosion can interfere with the potentiometer's ability to function correctly. Mechanical Damage: Impact or stress can damage the potentiometer's housing or internal mechanisms. |
| Circuit Components | The circuit typically consists of the potentiometer, wiring harness, connectors, and the seat control module. Each component plays a vital role in transmitting the voltage signal. | Open Circuit: A break in the wiring, often due to damaged wires or corroded connectors, prevents the signal from reaching the control module. Short to Ground: A wire chafing against the vehicle's chassis can create a short circuit, causing an incorrect voltage reading. Short to Voltage: A wire contacting another power source can send an abnormally high voltage to the control module. High Resistance: Corrosion or loose connections can increase resistance in the circuit, weakening the signal. |
| Seat Control Module (SCM) Role | The SCM receives the voltage signal from the potentiometer and uses it to control the seat recline motor. It interprets the voltage as a specific recline angle and activates the motor accordingly. | SCM Failure: Internal faults within the SCM can prevent it from correctly interpreting the potentiometer signal or controlling the seat motor. Software Glitches: Corrupted software or programming errors can lead to misinterpretation of the signal. Power Supply Issues: Insufficient or unstable power supply to the SCM can cause malfunction. |
| Symptoms of B1958 | The most common symptom is the inability to adjust the seat recline. Other symptoms include erratic seat movement, seat recline motor not functioning, or the seat getting stuck in a particular position. The diagnostic trouble code (DTC) B1958 will also be stored in the vehicle's computer. | No Seat Recline Function: The seat motor does not respond to the recline switch. Intermittent Seat Movement: The seat moves erratically or stops unexpectedly. Seat Stuck in Position: The seat cannot be reclined forward or backward. DTC B1958 Present: The vehicle's diagnostic system reports the B1958 code. Other Seat Functions Affected: In some cases, other seat functions might be affected due to the overall communication issue. |
| Diagnostic Procedure | The diagnostic process typically involves using a scan tool to read the DTCs, visually inspecting the wiring and connectors, testing the potentiometer's resistance, and checking the voltage signals at the SCM. A multimeter and wiring diagrams are essential tools. | Scan Tool Diagnosis: Reading and interpreting the DTCs. Visual Inspection: Checking for damaged wires, corroded connectors, and loose connections. Potentiometer Testing: Measuring the resistance of the potentiometer across its range of motion. Voltage Testing: Measuring the voltage at the potentiometer and SCM. Continuity Testing: Ensuring there are no breaks in the wiring harness. Ground Circuit Testing: Verifying a good ground connection for the seat control module. |
| Troubleshooting Steps | Start by visually inspecting the wiring and connectors for any signs of damage or corrosion. Then, use a multimeter to test the potentiometer's resistance and voltage output. If the potentiometer is faulty, replace it. If the wiring is damaged, repair or replace it. Finally, if the SCM is suspected, it may need to be reprogrammed or replaced. | Wiring Repair/Replacement: Repairing damaged wires and replacing corroded connectors. Potentiometer Replacement: Replacing the faulty potentiometer. SCM Reprogramming/Replacement: Reprogramming the SCM with the latest software or replacing it if necessary. Fuse/Relay Check: Verifying the integrity of fuses and relays related to the seat control circuit. Ground Point Inspection: Checking and cleaning ground points to ensure proper grounding. |
| Tools Required | A scan tool, multimeter, wiring diagrams, screwdrivers, pliers, wire strippers, and soldering iron are typically required for diagnosing and repairing this issue. | Scan Tool: For reading and clearing DTCs. Multimeter: For measuring voltage, resistance, and continuity. Wiring Diagrams: For identifying circuit components and wiring paths. Screwdrivers/Pliers: For accessing and manipulating wiring and connectors. Wire Strippers/Crimpers: For repairing and replacing wires and connectors. Soldering Iron: For making secure electrical connections. Terminal Release Tools: For safely disconnecting connectors without damaging them. |
| Related DTCs | Other DTCs related to seat functions, such as B1957 (Seat Recline Motor Circuit Failure), B1959 (Seat Position Sensor Circuit Failure), or communication errors with the SCM, may also be present. | B1957 (Seat Recline Motor Circuit Failure): Indicates a problem with the seat recline motor itself. B1959 (Seat Position Sensor Circuit Failure): Suggests a fault with another position sensor in the seat. U-Codes (Communication Errors): Point to communication problems between the SCM and other modules in the vehicle. B-Codes (Body Codes): General body-related fault codes that may indirectly affect seat function. |
| Safety Precautions | Always disconnect the negative battery cable before working on electrical components to prevent accidental shorts or injuries. Refer to the vehicle's service manual for specific safety procedures. | Battery Disconnection: Disconnecting the negative battery cable to prevent electrical shocks. Proper Grounding: Ensuring proper grounding when working with electrical components. Using Insulated Tools: Using insulated tools to prevent accidental shorts. Wearing Safety Glasses: Protecting your eyes from debris and sparks. Consulting Service Manual: Referring to the vehicle's service manual for specific safety procedures. |
Detailed Explanations:
Potentiometer Function: The potentiometer is a critical component in the seat recline system. It's essentially a variable resistor that provides a voltage signal to the seat control module (SCM). As the seat reclines forward or backward, the internal resistance of the potentiometer changes. This change in resistance directly affects the voltage signal sent to the SCM. The SCM then interprets this voltage to determine the precise angle of the seat recline, allowing it to control the seat motor accordingly.
Circuit Components: The B1958 circuit comprises several interconnected components. The potentiometer itself is the primary sensor. A wiring harness connects the potentiometer to the SCM, carrying the voltage signal. Connectors are used to join the wiring harness to the potentiometer and the SCM. Finally, the SCM acts as the control center, receiving the signal and controlling the seat recline motor. A failure in any of these components can lead to the B1958 DTC.
Seat Control Module (SCM) Role: The seat control module (SCM) is the "brain" of the power seat system. It receives the voltage signal from the potentiometer, which represents the seat's recline position. Based on this signal, the SCM activates and controls the seat recline motor to move the seat to the desired position. The SCM also monitors the system for faults and stores diagnostic trouble codes (DTCs) like B1958 when it detects a problem.
Symptoms of B1958: The most obvious symptom of a B1958 code is the inability to adjust the seat recline forward or backward. The seat might be stuck in one position, or the seat recline motor might not respond at all. In some cases, the seat movement might be erratic or intermittent. The presence of the B1958 DTC itself, as read by a scan tool, is also a key symptom. It's important to note any other seat functions that might be affected, as this can help narrow down the source of the problem.
Diagnostic Procedure: Diagnosing a B1958 code requires a systematic approach. First, use a scan tool to confirm the presence of the B1958 code and check for any other related DTCs. Next, perform a thorough visual inspection of the wiring and connectors associated with the seat recline system. Look for any signs of damage, corrosion, or loose connections. Then, use a multimeter to test the potentiometer's resistance and voltage output. Finally, check the voltage signals at the SCM to determine if the signal is reaching the module.
Troubleshooting Steps: After diagnosing the problem, follow these troubleshooting steps. Begin by addressing any visible damage to the wiring or connectors. Repair or replace any damaged wires or corroded connectors. If the potentiometer is faulty, replace it with a new one. If the wiring and potentiometer appear to be in good condition, suspect the SCM. In some cases, the SCM can be reprogrammed. However, if it is severely damaged, it may need to be replaced.
Tools Required: Several tools are essential for diagnosing and repairing a B1958 code. A scan tool is needed to read and clear DTCs. A multimeter is required for testing voltage, resistance, and continuity. Wiring diagrams are crucial for identifying circuit components and wiring paths. Screwdrivers, pliers, wire strippers, and a soldering iron are necessary for repairing and replacing wiring and connectors. Terminal release tools help to safely disconnect connectors without damaging them.
Related DTCs: The B1958 code is often accompanied by other DTCs related to seat functions. B1957 (Seat Recline Motor Circuit Failure) indicates a problem with the seat recline motor itself. B1959 (Seat Position Sensor Circuit Failure) suggests a fault with another position sensor in the seat. "U" codes, such as U0100, indicate communication problems between the SCM and other modules in the vehicle. "B" codes are general body-related fault codes that may indirectly affect seat function.
Safety Precautions: Always disconnect the negative battery cable before working on electrical components. This will prevent accidental shorts and potential injuries. Ensure proper grounding when working with electrical components. Use insulated tools to prevent accidental shorts. Wear safety glasses to protect your eyes from debris and sparks. Always refer to the vehicle's service manual for specific safety procedures.
Frequently Asked Questions:
Question: What does the B1958 code mean? Answer: The B1958 code indicates a fault in the seat recline forward/backward potentiometer feedback circuit, meaning the seat control module isn't receiving the correct signal about the seat's recline position. This typically results in seat recline malfunction.
Question: Can I fix the B1958 code myself? Answer: Depending on your mechanical and electrical skills, you might be able to fix it. Start with visual inspection and basic testing, but complex issues might require a professional technician.
Question: How much does it cost to fix a B1958 code? Answer: The cost can vary widely depending on the cause of the problem. A simple wiring repair might be inexpensive, while replacing the potentiometer or SCM can be more costly. Expect to pay anywhere from $100 to $500 or more.
Question: What happens if I don't fix the B1958 code? Answer: The primary consequence is the inability to adjust the seat recline, which can be uncomfortable and potentially unsafe. In some cases, the seat might be stuck in an undesirable position.
Question: Is the B1958 code a serious problem? Answer: While not immediately dangerous, a malfunctioning seat recline can be uncomfortable and distracting while driving. It's best to address the issue for optimal comfort and safety.
Conclusion:
The B1958 DTC signifies a problem within the seat recline potentiometer feedback circuit, often leading to seat adjustment issues. By following a systematic diagnostic and troubleshooting approach, including visual inspection, component testing, and wiring repair, you can effectively resolve this issue and restore proper seat functionality.