Introduction
The B1656 diagnostic trouble code (DTC) indicates a problem within the circuit controlling the rear upward movement of the driver's seat. This means the vehicle's computer (often the Body Control Module or Seat Control Module) has detected an open circuit in the wiring or components responsible for raising the rear portion of the driver's seat. This can result in the seat not adjusting properly, leading to discomfort and potentially affecting driving safety. Addressing this issue promptly is crucial for both comfort and functionality.
Comprehensive Table: B1656 Seat Driver Rear Up Circuit Open
| Category | Description | Possible Causes |
|---|---|---|
| Code Definition | B1656: Seat Driver Rear Up Circuit Open | N/A |
| Symptoms | Driver's seat rear upward adjustment inoperative. Seat may be stuck in one position. Possible other seat adjustments are also not working. Illuminated Check Engine Light or other warning lights (depending on vehicle). Erratic seat movement. | N/A |
| Affected Components | Driver's seat rear up/down adjustment motor. Wiring harness and connectors related to the seat adjustment circuit. Seat Control Module (SCM) or Body Control Module (BCM). Seat adjustment switch. Fuses and relays associated with the seat adjustment system. | N/A |
| Common Causes | Open circuit in the wiring harness. Damaged or corroded connector. Faulty driver's seat rear up/down adjustment motor. Defective Seat Control Module (SCM) or Body Control Module (BCM). Blown fuse. Faulty seat adjustment switch. Rodent damage to wiring. | N/A |
| Diagnostic Steps | 1. Check for related DTCs. 2. Inspect fuses related to the seat adjustment system. 3. Visually inspect wiring harness and connectors for damage or corrosion. 4. Test the seat adjustment switch for proper operation. 5. Test the seat adjustment motor for continuity and voltage. 6. Check the SCM/BCM for proper operation (requires specialized equipment). 7. Use a wiring diagram to trace the circuit and identify the open. 8. Verify ground connections. 9. Perform a wiggle test on the wiring harness to see if the circuit intermittently opens. | N/A |
| Tools Required | Multimeter. Wiring diagram. Test light. Socket set. Screwdrivers. Connector cleaner. Scan tool (for reading and clearing DTCs and potentially for SCM/BCM testing). Wire strippers and crimpers (for wiring repairs). Possibly a seat adjustment motor removal tool. | N/A |
| Severity | Moderate. Inconvenient and uncomfortable, but typically doesn't directly affect the vehicle's drivability. However, an improperly adjusted seat can affect driving safety and ergonomics. | N/A |
| Potential Repair Costs | Varies widely depending on the cause. A blown fuse might be a few dollars. A wiring repair could range from $50 to $300. A new seat adjustment motor could cost $200 to $500 plus labor. A new SCM/BCM could be even more expensive. | N/A |
| Related DTCs | Other seat adjustment codes (e.g., B1657, B1658 for other seat directions). Codes related to the SCM or BCM. Codes related to power supply issues. | N/A |
| Vehicle-Specific Information | Consult the vehicle's service manual for specific wiring diagrams, component locations, and testing procedures. Different manufacturers and models may have different seat adjustment systems. | N/A |
| Wiring Diagram Importance | Crucial for identifying the specific wires involved in the driver's seat rear up/down adjustment circuit. Helps in tracing the circuit and pinpointing the location of the open. | N/A |
| Connector Inspection | Carefully inspect connectors for bent or broken pins, corrosion, and loose connections. Clean connectors with electrical contact cleaner. Ensure connectors are properly seated and locked. | N/A |
| Motor Testing | Use a multimeter to check for continuity through the motor windings. Apply voltage directly to the motor terminals (with appropriate polarity) to see if it operates. Be careful not to overload the motor. | N/A |
| SCM/BCM Testing | This often requires specialized scan tools and diagnostic procedures. Some scan tools can perform output tests to activate the seat adjustment motor directly. Check for software updates for the SCM/BCM. | N/A |
| Wiggle Test | With the multimeter connected to the circuit, gently wiggle the wiring harness along its length. If the multimeter reading changes (e.g., shows an open circuit intermittently), this indicates a possible break in the wire. | N/A |
| Ground Connection | A bad ground connection can cause all sorts of problems. Check the ground connections related to the seat and seat control module. Make sure they are clean and tight. | N/A |
Detailed Explanations
Code Definition: The B1656 code specifically indicates an open circuit in the driver's seat rear upward adjustment circuit. This means the electrical path required for the seat to move upward at the rear is broken.
Symptoms: The most obvious symptom is the inability of the driver's seat to adjust upwards at the rear. Other seat adjustments might also be affected depending on the vehicle's design. A check engine light or other warning lights might illuminate, and the seat may move erratically.
Affected Components: The primary components involved are the driver's seat rear up/down adjustment motor, the wiring harness and connectors connecting the motor to the Seat Control Module (SCM) or Body Control Module (BCM), the SCM/BCM itself, the seat adjustment switch, and related fuses and relays.
Common Causes: The most frequent cause is an open circuit in the wiring harness, often due to a broken or damaged wire. A damaged or corroded connector can also disrupt the circuit. A faulty driver's seat rear up/down adjustment motor is another possibility. Less common causes include a defective SCM/BCM, a blown fuse, or a faulty seat adjustment switch. Rodent damage to the wiring is also a potential culprit, particularly if the vehicle has been parked for extended periods.
Diagnostic Steps: The diagnostic process involves a systematic approach. First, check for any related DTCs that might provide additional clues. Then, inspect the fuses related to the seat adjustment system. A visual inspection of the wiring harness and connectors is crucial to identify any obvious damage or corrosion. The seat adjustment switch should be tested for proper operation. The seat adjustment motor needs to be tested for continuity and voltage. Checking the SCM/BCM requires specialized equipment. Use a wiring diagram to trace the circuit and identify the open. Verify ground connections. Finally, perform a "wiggle test" on the wiring harness to see if the circuit intermittently opens.
Tools Required: A multimeter is essential for testing continuity and voltage. A wiring diagram is crucial for tracing the circuit. A test light can be used to check for power. A socket set and screwdrivers are needed for accessing components. Connector cleaner helps remove corrosion. A scan tool is required for reading and clearing DTCs and potentially for SCM/BCM testing. Wire strippers and crimpers are needed for wiring repairs. A seat adjustment motor removal tool might be necessary.
Severity: The severity of this issue is moderate. While it doesn't typically affect the vehicle's drivability directly, an improperly adjusted seat can affect driving safety and ergonomics, leading to discomfort and potential fatigue.
Potential Repair Costs: Repair costs can vary significantly. A blown fuse might be a simple and inexpensive fix. A wiring repair could range from $50 to $300. A new seat adjustment motor could cost $200 to $500 plus labor. Replacing the SCM/BCM could be even more expensive, potentially exceeding $1000.
Related DTCs: Other seat adjustment codes (e.g., B1657, B1658 for other seat directions) might be present. Codes related to the SCM or BCM or codes related to power supply issues could also be present.
Vehicle-Specific Information: It is crucial to consult the vehicle's service manual for specific wiring diagrams, component locations, and testing procedures. Different manufacturers and models may have different seat adjustment systems.
Wiring Diagram Importance: A wiring diagram is essential for identifying the specific wires involved in the driver's seat rear up/down adjustment circuit. It helps in tracing the circuit and pinpointing the location of the open.
Connector Inspection: Carefully inspect connectors for bent or broken pins, corrosion, and loose connections. Clean connectors with electrical contact cleaner. Ensure connectors are properly seated and locked.
Motor Testing: Use a multimeter to check for continuity through the motor windings. Apply voltage directly to the motor terminals (with appropriate polarity) to see if it operates. Be careful not to overload the motor.
SCM/BCM Testing: This often requires specialized scan tools and diagnostic procedures. Some scan tools can perform output tests to activate the seat adjustment motor directly. Check for software updates for the SCM/BCM.
Wiggle Test: With the multimeter connected to the circuit, gently wiggle the wiring harness along its length. If the multimeter reading changes (e.g., shows an open circuit intermittently), this indicates a possible break in the wire.
Ground Connection A bad ground connection can cause all sorts of problems. Check the ground connections related to the seat and seat control module. Make sure they are clean and tight.
Frequently Asked Questions
What does B1656 mean? B1656 means there's an open circuit in the driver's seat rear upward adjustment circuit. The vehicle's computer has detected a break in the electrical path.
Can I fix B1656 myself? Depending on your mechanical skills, you might be able to. Start with checking fuses and wiring, but complex issues may require professional help.
What causes a B1656 code? Common causes include broken wires, corroded connectors, a faulty seat motor, or a defective control module. Rodent damage is also a possibility.
How much does it cost to fix B1656? The cost varies widely, from a few dollars for a fuse to hundreds for a motor or control module replacement. The labor cost also affects the total.
Is B1656 a serious problem? It's moderately serious. While it doesn't usually affect driving directly, an improperly adjusted seat can affect comfort and safety.
Conclusion
The B1656 DTC indicates a problem with the driver's seat rear upward adjustment circuit, most likely an open circuit. A systematic diagnostic approach, starting with simple checks and progressing to more complex tests, is essential to pinpoint the cause and restore proper seat functionality.