B1446 on 2013-2017 Buick Encore: OnStar Backup Battery Failure Guide

What's Unique About the 2013-2017 Buick ENCORE

For the first-generation Buick Encore and many other GM vehicles from this era, the OnStar backup battery was treated as a long-life service item that eventually wears out. The system is designed to alert the driver to its failure via the B1446 code and a red OnStar light, ensuring awareness that the automatic crash response feature may not work without main vehicle power. The failure is a predictable result of battery age and not indicative of a larger electrical problem with the vehicle. The issue is shared across its platform mates, the Chevrolet Trax and Sonic.

Diagnostic Flowchart

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

Symptoms You May Notice

• Solid red light on the OnStar indicator (on the rearview mirror or overhead console 🎬 Watch: Why your OnStar light is red and how to fix it).
• OnStar system may be non-functional.
• "Service OnStar System" message may appear on the Driver Information Center (DIC).
• OnStar representative may confirm a diagnostic failure of the backup battery if contacted via a call.

Most Likely Causes

1. OnStar Backup Battery has reached the end of its service life 🔴 High Probability → Shop Vehicle Battery The battery is a non-rechargeable, consumable part with a finite lifespan, typically failing after 5-8 years of service due to natural chemical degradation.
   How to confirm: Scan the vehicle for B-codes. The presence of B1446, especially with symptom byte '03' (Voltage Below Threshold), is a definitive confirmation of battery failure.
   Typical fix: Replace the OnStar backup battery. This involves locating the VCIM (OnStar module) behind the glove box, powering down the vehicle correctly, opening the module, and swapping the old battery for a new one.
   Est. part cost: $40-$90

Rare But Worth Checking

• Wiring issue to the VCIM (OnStar Module): While rare, a damaged wire or loose connection could mimic a battery failure. This is unlikely unless other work has recently been performed in the area of the module.
• Failed Vehicle Communication Interface Module (VCIM): → Shop Telematics Interface Module It is possible for the module itself to fail, but the battery is a far more common point of failure. The battery should always be replaced first before condemning the entire module. A related customer satisfaction program (14395) was issued for some 2015 models for a faulty OnStar module that could drain the main vehicle battery, but this is a separate issue from the backup battery failing due to age.

Diagnosis Steps

1. Verify the complaint: Check for a solid red OnStar indicator light on the overhead console or rearview mirror.
2. Scan for Codes: Use a scan tool capable of reading B-codes (Body codes) to confirm B1446 is present. Note any symptom bytes like '03' (Voltage Below Threshold) for definitive confirmation.
3. Locate the VCIM: On the Buick Encore and its platform-mate Chevy Trax, the VCIM (OnStar module) is located behind the glove box assembly.
4. CRITICAL Follow TSB Procedure for Power Down: This step is essential to avoid destroying the new battery. Turn the ignition completely OFF. Open the driver's door to cancel Retained Accessory Power (RAP) and wait for all interior lights and the radio to turn off completely. TSB PIC4541F warns that disconnecting power while RAP is active will trigger the backup battery's one-time use function, permanently discharging it.
5. Access the Module: Remove the glove box assembly. This typically involves removing a side damper, squeezing the sides of the glove box to release the stops, and removing hinge screws.
6. Disconnect and Replace Battery: With the vehicle fully powered down, unplug the electrical connectors from the VCIM. Remove the module from its bracket, open the module's case (it is often clipped together), and swap the internal backup battery.
7. Reassemble and Clear Codes: Reinstall the module, reconnect its wiring, and reassemble the glove box. Reconnect the main vehicle battery if it was disconnected. Use a scan tool to clear the DTCs. The code should not return, and the OnStar light should turn green after a short initialization period.

Parts You'll Likely Need

• OnStar Backup Battery (OEM #42454411) — This is the consumable part that fails and triggers the code. Part numbers can vary by model year and module generation; always confirm with a dealer using your VIN. Another common GM number for this part is 23117460.
  Trusted brands: ACDelco, GM Genuine Parts
  OEM price range: $40-$90

Related Codes That Often Appear With This One

• B1447 — This code means 'Backup Power Source Open Circuit' and often appears with B1446. It indicates the module sees a completely dead or disconnected battery.

Technical Service Bulletins (TSBs) & Recalls

• PIC4541F: Diagnostic tip for OnStar back-up battery failure causing a red OnStar LED and DTC B1446 or B1447.
• 14395: A separate customer satisfaction program for some 2015 models regarding a faulty OnStar module (not the battery) causing a main battery drain.

Platform-Specific Known Issues

• GM issued Technical Service Bulletin (TSB) #PIC4541F, which directly addresses DTC B1446 and B1447 on the 2013-2017 Buick Encore. It identifies the cause as OnStar back-up battery failure. The TSB contains a critical warning: 'Do NOT disconnect the main vehicle battery or remove the OnStar fuse with the ignition key in any position other than OFF. Retained accessory power (RAP) should be allowed to time out or be canceled (simply opening the driver's door should cancel RAP) before disconnecting power.' It explains that failure to do so 'will permanently discharge the back-up battery' because the system interprets the power loss as a collision event and activates its one-time, non-rechargeable power reserve.

Mechanic-Grade Diagnostic Values

• Backup Power Source Voltage at VCIM Connector — expected: 12.3-12.9 volts. Failure: Voltage is not within the specified range.
• Conditions for running the DTC — expected: System voltage between 9.5 and 15.5 V with the ignition in RUN or ACC.. Failure: The VCIM detects the backup power source voltage has dropped below the minimum threshold.

Hidden / Shadow Codes Worth Checking

• B1446 03: Replace Backup Power Source Voltage Below Threshold. This is the most common symptom byte and definitively points to a failed backup battery. (see via A professional scan tool like the GM GDS2/MDI or an equivalent tool capable of reading manufacturer-specific symptom bytes.)
• B1447 04: Backup Power Source Open Circuit. This often accompanies B1446 and indicates the module sees a completely dead or disconnected battery. (see via A professional scan tool like the GM GDS2/MDI or an equivalent tool capable of reading manufacturer-specific symptom bytes.)

Scan Tool Commands That Help

• GDS2 / Techline SPS: VCIM Vehicle Communication Interface Module Set-up — This function is required ONLY if the entire OnStar module (VCIM) is replaced, not for a simple battery change. It configures the new module for the specific vehicle.
• GDS2 / Techline SPS: ONSA-OnStar Activation — This function is used after a new VCIM is installed and programmed. It sends the new module's data to the OnStar network to activate the subscription services.

Wiring & Ground Locations

• VCIM Connector X1, Pin 13 — On the main harness connector for the OnStar module (VCIM) located behind the glove box.. This is the low reference (ground) circuit for the backup battery. It is used in conjunction with Pin 14 to test the battery voltage directly at the module connector.
• VCIM Connector X1, Pin 14 — On the main harness connector for the OnStar module (VCIM) located behind the glove box.. This is the positive voltage supply circuit from the backup battery. Testing voltage between this pin and Pin 13 confirms if the battery is supplying power to the module.

OEM Part Supersession History

• 88861186 → 22704633, 42454411 — Part number updates and consolidation by GM over time.
  Heads up: These part numbers are generally interchangeable for this function across many GM models from the era. However, always verify the correct part for your specific VIN with a GM dealer.