B1446 on 2010-2017 Buick LaCrosse: OnStar Backup Battery Failure Causes and Fixes

What's Unique About the 2010-2017 Buick LACROSSE

This is an extremely common code across all GM vehicles from this era, including the Buick LaCrosse. The OnStar backup batteries have a finite service life, typically 5-7 years. As the 2010-2017 model years have all passed this age, battery failure is not a matter of 'if' but 'when'. The code is a straightforward indicator of an aged component reaching the end of its life.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Generation note: The 2010-2017 year range covers two LaCrosse generations, and the repair differs significantly between them. * Second Generation (2010-2016): The OnStar module (VCIM) is located inside the trunk, mounted to the upper package shelf or behind the driver's side trunk liner, making the backup battery easy to access and replace. Many owners report completing the replacement in under 15 minutes. * Third Generation (2017): The module location is more difficult to access. On similar contemporary GM platforms like the Buick Encore, the module is found behind the glove box. Owners of a 2017 model should be prepared for a more involved repair that requires removing interior trim panels. A Reddit thread discussing the 2017 LaCrosse's main battery highlighted the general electrical complexity, with one user noting that many shops are reluctant to work on it due to the dense wiring.

Symptoms You May Notice

• Solid red OnStar status light on the rearview mirror.
• "Service OnStar" message may appear on the Driver Information Center (DIC).
• In some related GM vehicles, owners have anecdotally reported that a failing OnStar battery contributed to a faster drain on the main vehicle battery, though this is not a primary or guaranteed symptom.

Most Likely Causes

1. Failed OnStar Backup Battery 🔴 High Probability → Shop Vehicle Battery The original batteries have a designed service life of 5-7 years, and all vehicles in this date range are now old enough to experience age-related failure.
   How to confirm: Confirm code B1446 or B1447 with an OBD-II scanner and observe a red OnStar indicator light. Given the age of the vehicle and the prevalence of this issue documented in GM TSBs, this is almost certainly the cause.
   Typical fix: Replace the OnStar backup battery module. This involves locating the VCIM, properly powering down the vehicle, disconnecting the module, and swapping the old battery for a new one.
   Est. part cost: $30 - $75

Rare But Worth Checking

• Faulty VCIM (OnStar Module): This is very rare. If replacing the backup battery does not clear the code and resolve the red light, the module itself may have failed. However, always replace the battery first.
• Wiring Harness Issue: Damage to the wiring leading to the VCIM could theoretically cause this code, but it is highly unlikely compared to simple battery failure.

Diagnosis Steps

1. Verify the trouble code B1446 (and/or B1447) using an OBD-II scanner capable of reading Body (B) codes.
2. Confirm the primary symptom: a solid red light on the OnStar buttons (typically on the rearview mirror).
3. CRITICAL STEP: Turn the ignition completely OFF. Open the driver's door to cancel Retained Accessory Power (RAP) and wait a few minutes for all modules to power down. Per TSB PIC4541, disconnecting power to the OnStar module while the ignition is ON or RAP is active will activate the new backup battery, permanently discharging and ruining it.
4. Locate the Vehicle Communication Interface Module (VCIM). For 2010-2016 models, this is on the underside of the rear package shelf or behind the liner on the driver's side of the trunk. For 2017 models, check behind the glove box.
5. Disconnect the wiring harnesses from the VCIM. Per TSB guidance, disconnect the main harness connector first.
6. Remove the old backup battery and install the new one.
7. Re-install the module, reconnect the wiring harnesses, and secure any trim panels that were removed.
8. Clear the trouble codes with the scanner. Start the vehicle and verify the OnStar light turns green after its initial check. The "Service OnStar" message should also be gone.

Parts You'll Likely Need

• OnStar Backup Battery (2010-2016) (OEM #22704633) — This is the direct replacement for the failed internal battery for the 2010-2016 LaCrosse. It is a non-rechargeable, single-use component that fails with age. This part may be superseded by 84535336.
  Trusted brands: ACDelco (GM Genuine Part), Dorman, Ultralast
  OEM price range: $40-$75
  Aftermarket price range: $30-$50
• OnStar Backup Battery (2017) (OEM #84535336 (Verify by VIN)) — The 2017 model uses a newer generation of OnStar hardware and likely requires a different battery. Part number 84535336 is a common replacement for many newer GM vehicles, but it is critical to verify the correct part number with a dealer using your vehicle's VIN before purchasing.
  Trusted brands: ACDelco (GM Genuine Part)
  OEM price range: $40-$60
  Aftermarket price range: $30-$50

Related Codes That Often Appear With This One

• B1447 — B1446 indicates the battery voltage is low, while B1447 indicates an open circuit in the backup battery. Both codes point to the same root cause: a failed OnStar backup battery. They often appear together or interchangeably.

Technical Service Bulletins (TSBs) & Recalls

• PIC4541F: Provides diagnostic advice for a red OnStar LED and DTCs B1446 or B1447, warning technicians not to disconnect power improperly.
• PIC4541A/D: Earlier versions of the same TSB, which list a wide range of affected GM vehicles and confirm the root cause and repair procedure.

Platform-Specific Known Issues

• Per TSB PIC4541F, it is absolutely critical to power down the vehicle correctly before service. Disconnecting power to the OnStar module while the ignition is on or Retained Accessory Power (RAP) is active can permanently discharge the new backup battery, requiring it to be replaced again.

Scan Tool Commands That Help

• GDS2 / TIS2Web: VCIM Setup and Activation — This function must be performed after replacing the entire VCIM (OnStar Module). It ensures the new module is correctly configured to the vehicle and can communicate with the network. Failure to perform setup can result in a non-functional OnStar system even with new parts.
• GDS2 / TIS2Web: WIFI Enable — For 2015 and newer models equipped with OnStar Gen10 with WiFi (RPO VV4), this function must be run *after* the VCIM Setup and Activation. If run before, the WiFi setting will not be retained, and the hotspot will be inoperative.

Wiring & Ground Locations

• Fuse F5 (Instrument Panel) — In the fuse box located under the dashboard on the driver's side for 2010-2016 models.. This 7.5A fuse specifically powers the Vehicle Communications Interface Module (VCIM). While a blown fuse is a very rare cause for B1446 (which indicates low battery voltage, not total power loss), checking this fuse is a valid preliminary step in a complex electrical diagnosis.
• Ground G103 — On later model GM vehicles, this ground is often located on the left frame rail, sometimes under the Starter Generator Control Module bracket. Other GM documentation places it on the cowl above the brake booster.. This is a major ground point for multiple critical modules, including the BCM, Instrument Panel Cluster (IPC), and Data Link Connector (DLC). While not the primary cause for an isolated B1446 code, a poor connection at G103 can cause widespread, intermittent communication and electrical issues. If other strange electrical symptoms are present with B1446, inspecting this ground is a wise diagnostic step.

Real Owner Repair Stories

• Reddit user @sasquatch_melee (Buick Regal TourX (similar GM platform to 2017+ LaCrosse)) — User was proactively looking for the OnStar module to disable it.
  ✅ What actually fixed it The user located the OnStar module behind the fuse block in the driver's side footwell. This provides real-world confirmation of the difficult, under-dash location for this generation of GM vehicles, contrasting with the easy trunk access of the 2010-2016 LaCrosse.

Model Year Variations Within This Range

• 2015-2017: Models equipped with OnStar Generation 10 hardware featuring a 4G LTE WiFi hotspot (RPO VV4) require an additional programming step after VCIM replacement. A technician must use the GM TIS2Web service to perform a "WIFI Enable" function after the standard module setup and activation.