Lost Communication with Seat Control Switch Module B
The U0261 code indicates that the main control module (ECM/PCM or bus communication module) has detected a loss of communication with the Seat Control Switch Module 'B'. This module manages the power seat functions for the passenger or secondary seats, including position, lumbar, heating, or ventilation. Communication typically occurs over the CAN (Controller Area Network) or LIN (Local Interconnect Network) bus, depending on the vehicle architecture. The loss of communication can be caused by wiring faults, corroded connectors, internal module failure, or interruptions in the vehicle's communication network.
1. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.
2. Most Common Causes
- Damaged, corroded, or disconnected wiring or connector between the seat switch module and the data bus
- Internal failure of the Seat Control Switch Module 'B' (passenger or secondary seat module)
- Open or short circuit in the CAN/LIN communication line
- Fault in the master control module (gateway or body control module) that manages communication
- Low voltage or power supply failure to the seat switch module
- Abnormal bus resistance due to faulty additional modules
3. Symptoms You Will Notice
- Malfunction indicator lamp (MIL) illuminated
- Power seat functions (position, lumbar, heat, ventilation) inoperative for the affected seat
- Seat controls unresponsive or intermittent operation
4. Step-by-Step Diagnosis
Scan for other related communication codes to identify the scope of the issue
Inspect the wiring and connectors at the seat switch module for damage, corrosion, or loose connections
Check the CAN/LIN bus voltage and resistance at the module connector
Test power and ground supply to the seat switch module
If wiring and power are OK, suspect a faulty seat switch module and replace it
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, it is generally safe to drive, but the affected seat's power functions will not work. The issue does not affect vehicle drivability.
How much does it cost to fix?▼
Repair costs typically range from $100 to $400, depending on whether it's a wiring repair (lower end) or module replacement (higher end).