2021-2024 BMW X5/X6/X7 Seat Initialization Issues

BMW has released Service Information Bulletin SIB 52 23 19 to address a range of concerns related to seat operation and functionality in 2021-2024 BMW X5, X6, and X7 models. This comprehensive bulletin, which is Revision 16 dated October 20, 2023, supersedes previous versions including SI B52 23 19 from February 2023 and TRI B52 23 19. It provides detailed information for technicians on the complex networked seat systems in these vehicles, aiming to resolve issues that owners might experience with seat adjustments, warning messages, and overall seat performance.

The bulletin highlights that the vehicle's three rows of seats communicate with one another, meaning a problem with one seat can impact the operation of others. This interconnectedness is designed to prevent interference during operation. Owners searching for solutions to their BMW X5 seat initialization problems or other seat-related faults will find this information critical.

Symptoms

Owners of affected BMW X5, X6, and X7 vehicles may notice several symptoms related to seat malfunctions. These can include seats that do not move as expected, difficulty accessing third-row seating, or issues with seat heating. Specific warning messages may also appear on the vehicle's display.

Common symptoms include:

• Seats that fail to initialize correctly, leading to disabled functions.
• Intermittent failure of seats to latch, especially after returning from the Easy Entry position.
• Difficulty with second-row seats blocking access to the third row.
• Unusual noises emanating from seats during operation.
• A Check Control Message (CCM) displaying "Left rear seat back unlocked."
• Seat heating functions being disabled if a seat is not initialized.
• Second and third-row seats not folding or moving to the EZ open position.

Fault Codes / DTCs

When seat issues occur, specific Diagnostic Trouble Codes (DTCs) may be stored in the vehicle's control modules. These codes help technicians pinpoint the exact nature of the problem. For issues related to the "Left rear seat back unlocked" message, the following fault codes may be present:

Code	Description	Module
ACSM6 930D6E	Backrest Sensor left 2nd seat row defect	Air Bag Control Module (ACSM6)
BDC 804990	locking 2nd seat row left, Easy Entry: locking state not plausible	Body Domain Controller (BDC)

Another related fault label mentioned in the bulletin is "Seat not locked CCM", which is associated with software updates.

Diagnosis / Trigger Conditions

Diagnosing seat issues in these BMW models requires a thorough understanding of their networked seat systems. The SIB outlines various conditions that can trigger malfunctions:

• Improper Seat Initialization: Seats must be fully assembled with seat leather and foam for proper initialization. If headrests are raised, they can interfere with the initialization process. A seat that is not initialized can lead to disabled functions, including seat heating.
• Time Delays in Button Controls: There is a time delay between pressing a seat button and the seat responding. Pressing the button a second time too quickly can cancel the operation.
• Foreign Objects: Foreign objects in the safety belt receptacle can inhibit seat operation by making the system think the seat is occupied.
• Missing or Incorrect Washers: Manufacturing tolerances in 60/40 seat rail assemblies sometimes required adding 2 mm washers. If these washers are missing or incorrectly installed when a seat is reinstalled, the seat may intermittently not latch, affecting cam interlock functioning.
• Damaged Wiring Harness: The wiring harness near the folding seatback can be damaged if incorrectly routed.
• Seat Rail End Stop: The mechanical end stop on seat rails must be transferred to a new rail if replaced; failure to do so will prevent seat initialization.
• Crash Lock Spring: An incorrectly positioned crash lock spring can prevent the latch spring from loading properly, which is a safety concern.
• Shipping Position: Replacement seats may arrive in a folded-flat shipping position, requiring specific electrical or mechanical procedures to unfold them before manual releases can function.

Important Warnings

BMW SIB 52 23 19 includes several critical warnings and advisories for both technicians and owners to ensure proper seat function and safety:

• "Do not operate seats unless they are initialized." Operating uninitialized seats can lead to interference and malfunction.
• "NOTE: 2nd and 3rd row seats will not fold or move to the EZ open position if the vehicle sees an occupant in the seat." This is a safety feature to prevent unintended movement.
• "NOTE: Seats will not fold if the vehicle sees an occupant in the seat." Similar to the above, this prevents folding when occupied.
• "NOTE: The center section (20%) is a monitored status. If this is folded down, it can influence the front seat backrest position if the vehicle thinks there will be interference between the seats." This highlights the interconnectedness of seat components.
• "If the washer is left out when the seat is reinstalled the seat: may intermittently not latch when returning from the EZ entry position. This can influence the cam interlock functioning." This emphasizes the importance of correct assembly.
• "When replacing a seat rail, this end stop must be transferred to the new rail. Failure to install these end stops will prevent the seat from initializing." This is a crucial step for seat rail replacement.
• "This spring keeps the latch spring loaded so it won't release in case of an accident." Proper installation of the crash lock spring is vital for safety.
• "NOTE: To remove the rear seat headrest assembly, you must remove the headrest leather cover. This cover will be destroyed during removal and will have to be replaced." Owners should be aware of this potential additional cost if headrest removal is needed.
• "Seat must NOT be in Easy Entry position during the fastener torquing" and "Seat must NOT be fully forward when torquing the fasteners." These are specific instructions for technicians during assembly.
• "Raising the headrest back into the upright position must be done by pushing up on it by hand." This clarifies the manual operation required for headrests after certain movements.
• "If a button is pressed before seat movement is finished it will stop the seats operation." This explains why seats might stop mid-movement if buttons are pressed repeatedly.
• "The seats will move around to avoid collision. They shouldn't be operable again until the seat behind them is in its fixed position again." This describes the collision avoidance logic and operational lockout.
• "An object or a passenger's presence is not sufficient to stop the seat from continuing to move. The seats are not touch sensitive for anti-pinch, there must be felt/added resistance." This clarifies the anti-pinch mechanism.
• "PRESSING ANY SEAT BUTTON WILL CANCEL THE SEAT'S MOVEMENT." and "PRESSING AGAINST A SEAT ALREADY IN MOTION WILL STOP THE SEAT." These are owner actions to stop unwanted seat movement.
• "IF BOTH SEATS OF THE 3RD ROW SEATS ARE FOLDED, IT WILL DISABLE THE USE OF THE 5TH ZONE CLIMATE CONTROL (IF EQUIPPED WITH COLD WEATHER PACKAGE)." This is an important functional limitation for owners with specific options.

Seat Operation and Features

This SIB provides extensive detail on the operation and components of the seats in BMW G05 (X5), G06 (X6), and G07 (X7) models, which feature a new style of networked seats introduced with the G05 in August 2018.

Seat Initialization Process

To properly initialize the seats, they must be fully assembled. The initialization process has a time limit. If the seat leather/foam is not present, the motor can move the seat frame past its intended stopping point, causing initialization to fail. Second-row headrests must be in the fully down position during initialization to prevent interference. If a seat is not initialized, functions like seat heating may be disabled.

Technicians can manually initialize a seat by selecting the desired seat module (SMFA - Seat Module Driver, SMBF - Seat Module Passenger, SMFAH - Seat Module Driver's Side Rear, SMBFH - Seat Module Passenger Side Rear) from the vehicle test screen and then choosing 'Call up ECU Functions' followed by 'Seat Adjustment'.

Seat Adjustments

The seats offer various adjustments, including headrest restraint height, backrest upper section, backrest angle, backrest width, forward/back, seat height, seat angle, seat depth, and lumbar support. Many of these functions are also available for rear seats.

Seat Motor and Component Details

The bulletin details various seat motors and components:

• Forward / Back Adjustment Motor SLV: The plastic tray for this motor is only available with the seat rail assembly. The motor and flexible shafts (part number 52 10 7 314 203) are available separately.
• Upper Backrest Adjustment Motor LKV: The motor and flexible shaft (part number 52 10 7 454 056) are available separately.
• Lower Backrest Adjustment Motor: Controls rear seat backrest movement and height adjustment.
• Seat Angle Adjustment: Uses a drive unit for seat cushion tilt adjustment.
• Head Restraint Adjustment Motor: Controls head restraint height adjustment.
• Backrest Width / Lumbar Adjustment Motors: These systems use compressed air lines and an electrically driven pneumatic pump.
• Cooling Fan Motors: These fans draw heat away from the body, differing from previous models that blew air onto the body.

Second Row Seat Features

Second-row seats have a safety interlock (J-hook) in the normal seating position to prevent upward movement unless slid forward. If a seat is not initialized, this interlock can interfere. The safety belt receptacle is monitored by a Hall-effect sensor to detect occupancy, which can affect seat operation if foreign objects are present.

Controls for the second row are located on the driver's seat-mounted switch block, the driver's door-mounted switch block, and the C-pillar/D-pillar mounted switch blocks. The 2nd row Lift / Tilt adjustment lever allows access to the 3rd row. The middle 20% section of the 60/40 split seat can be folded independently.

Third Row Seat Features

Third-row seats, particularly in the G07 X7, have power seat controls located on the C-pillar. These buttons (S311 and S312) lower or raise the seatback. There is one motor in the rear seat that controls three Bowden cables for headrest folding, pin pulling for locking, and seat folding. Raising the headrest back to the upright position must be done manually.

For diagnosis of the head restraint and/or backrest of the third seat row, Service Bulletin B52 09 20 is referenced. A Bowden cable routing change was implemented in third-row backrests starting February 2023 production, requiring new routing for vehicles produced prior to this date (see SIB B52 14 23).

Required Tools or Parts

Several specific parts and tools are mentioned for diagnosis and repair:

• 52 20 5A37D34: Spare part kit microswitch (for cam interlock).
• 52 20 5A37D37: (Washer) Spare part kit EE window (for cam interlock).
• 52 20 9872574: (Bolt) Repair set armrest.
• 52 10 7 454 056: Flexible shaft and small parts (Upper Backrest adjustment motor LKV).
• 52 10 7 469 879: (Seat End Stop) Spacer.
• 52 10 7 314 203: Flexible Shafts and small parts (Forward / Back adjustment motor SLV).
• 07 14 9 321 690: (Bolt) Holds seat adapter to seat frame (Business/Captain seats – 4 per seat).
• 07 11 9 908 419: (Bolt) Holds seat bottom to seat backrest (Business/Captain seats – 4 per seat).
• 83 19 0 445 309: Adhesive tape for installing the rear panel on the backrest of the third-row seat.
• 83 30 0 492 518: Wheel lock kit (use the #32 socket for new style 16-point internal seat mounting bolts).
• 36 13 6 765 545: Special tool for new style 16-point internal seat mounting bolts.

Repair Procedure Summary

Addressing seat issues often involves specific diagnostic and repair steps:

1. Seat Initialization: Ensure seats are fully assembled with leather/foam and headrests are fully down before attempting initialization. Use ISTA to select 'SERVICE FUNCTIONS', 'BODY', 'SEATS', and then the correct ABL test plan for the relevant seat. If a seat is not initialized, functions like seat heating may be disabled.
2. Addressing Latching Issues: For second-row 60/40 bench seats that intermittently won't latch, inspect for missing or incorrectly installed 2 mm washers under the seat rail. If present, ensure they are correctly installed. Refer to SI B52 04 19 and SI B52 19 19 for specific guidance on driver's and passenger's side seats, respectively. For G05 passenger side seats produced from 8/1/22 to 10/1/22, refer to SI B52 06 22.
3. Cam Interlock Functioning: If the cam interlock jams, check for issues with washers. The spring lock beveled star washer (P/N 52 20 5A37D37) must maintain contact with the spring to prevent damage to the cam interlock. A replacement microswitch with plastic cap for the 60/40 seat is P/N 52 20 5A37D34.
4. Seat Rail End Stop Transfer: When replacing a seat rail, the mechanical end stop (P/N 52 10 7 469 879) must be transferred to the new rail to allow proper seat initialization.
5. Wiring Harness Inspection: Inspect the wiring harness near the folding seatback for damage and ensure correct routing.
6. Software Updates: For issues like "Seat not locked CCM" or general seat operation improvements, check for available software updates (e.g., S18A-22-11-530 or higher, see SI B52 09 22). Software improvements from August 2019 (SI B52 21 19) changed certain seat operations, and older G05/G07 vehicles can be updated to 7/2019 SW (SI B65 19 19).
7. Third Row Backrest Bowden Cable: For third-row backrest Bowden cable routing and length changes, refer to SI B52 14 23. Replacement parts are designed for the new shortened cable and require new routing for vehicles produced prior to February 2023.

Owner Action

If you experience any of the symptoms described, especially issues with BMW X5 seat initialization or warning messages like "Left rear seat back unlocked," it is recommended to:

• Observe Seat Behavior: Note down specific warning messages, conditions under which the fault occurs, and any unusual noises.
• Attempt Basic Reset: For some issues, pressing any seat button will cancel current seat movement. If a seat is stuck, try pressing a different seat button to stop its operation.
• Visit a BMW Service Center: Due to the complex networked seat systems and the need for specialized diagnostic tools and procedures, it is best to have a qualified BMW technician diagnose and repair the issue. They can perform proper seat initialization, check for missing components, apply necessary software updates, and ensure all safety mechanisms are functioning correctly.
• Be Aware of Warnings: Pay attention to warnings such as not operating uninitialized seats or the conditions under which seats will not fold if occupied.

Revision History and Related Bulletins

This Service Information Bulletin SIB 52 23 19 (Revision 16, dated October 20, 2023) replaces previous versions, including SI B52 23 19 dated February 2023 and TRI B52 23 19. It also references numerous other related SIBs for specific issues:

• B52 03 23: Second seat row blocking access to third seat row, program seat modules; creasing/ripples in 2nd row 60/40 Bench Seat; scratching noise from 2nd row during operation.
• B52 11 23: Visible stitching on first row sport seat.
• B52 14 23: Third seat row backrest Bowden cable routing and length change.
• B52 04 22: Instructions to modify cam if washer is not needed by production date.
• B52 01 19: G05-G07 Seat Troubleshooting 6 Passenger; front seat noises; seat rail end stops.
• B52 02 19: G05-G07 Seat Troubleshooting 7 Passenger.
• B52 09 20: Diagnosis of head restraint and/or backrest of the third seat row.
• B52 05 20: Backrest misalignment of 60/40 second row seat; attachment for unfolding shipping-position seats.
• B52 05 21: Latch mechanism mounting nuts rework.
• B52 09 22: Software update for "Seat not locked CCM."
• B52 06 19: Various noises from 2nd row 60/40 mechanically adjusted seat.
• B52 06 22: 2nd row 60/40 Passenger bench seat in G05 produced 8/1/22 to 10/1/22 that intermittently won't latch.
• B72 04 17: Seat occupancy mat (CIS) warnings on vehicles produced up to 9/2018.
• B52 10 19: Seat cover coming off thigh support.
• B52 13 19: Noises from front seat headrest during operation.
• B52 21 19: Software improvements from August 2019 changing seat operations.
• B65 19 19: Update G05/G07 vehicles produced up to August 1, 2019 to 7/2019 SW.
• Recall 22V-670: Third row seat latch doesn't fully lock.

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Source: NHTSA ID: 10244258