B1446 on 2006-2013 Chevrolet Impala: OnStar Backup Battery Failure Causes and Fixes

What's Unique About the 2006-2013 Chevrolet IMPALA

The 9th generation Impala, like many GM vehicles from this era, was equipped with an OnStar system that uses a non-rechargeable lithium backup battery. This battery has a finite service life, typically lasting 5-10 years. As these vehicles have aged, battery failure has become an extremely common and expected maintenance issue, rather than a sign of a more complex electrical problem. 🎬 Watch: What a red OnStar light means for your battery. The failure is so common that GM issued Technical Service Bulletin PIC4541E (and later PIC4541F) to address it across a wide range of models, including the Impala.

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, typically on the rearview mirror or overhead console.
• OnStar system is inoperative or reports a problem.
• A voice message from the OnStar system upon vehicle startup indicating a system issue.
• Inability to use OnStar services or connect to an advisor.

Most Likely Causes

1. Failed OnStar Backup Battery 🔴 High Probability → Shop Vehicle Battery The original backup battery is a non-rechargeable lithium unit with a limited lifespan. Failure due to age is inevitable and documented in GM service bulletins.
   How to confirm: The presence of code B1446 is the primary confirmation. The OnStar status light will be red.
   Typical fix: Replace the backup battery pack inside the OnStar module (VCIM).
   Est. part cost: $20-$50

Rare But Worth Checking

• Wiring or Connector Issue at VCIM: If a new battery does not resolve the code, inspect the wiring harness and connector pins at the OnStar module for corrosion or damage. This would be the next logical step according to diagnostic procedures.
• Failed OnStar Module (VCIM): → Shop Telematics Interface Module This is very uncommon for this specific code. The module itself should only be suspected if a new battery and confirmed-good wiring do not solve the problem. A failing VCIM more commonly presents with other codes like B1000 or U1500.

Diagnosis Steps

1. Confirm the presence of code B1446 using an OBD-II scanner capable of reading B-codes (Body codes).
2. CRITICAL: Turn the ignition completely OFF. Open and close the driver's door to ensure Retained Accessory Power (RAP) is deactivated. Failure to do this before disconnecting power can permanently drain a new backup battery.
3. Disconnect the negative terminal of the main vehicle battery located under the hood to ensure safety.
4. Locate the Vehicle Communication Interface Module (VCIM). In a 2006-2013 Impala, it is located in the trunk on the driver's side, behind the trunk liner near the wheel well.
5. Pull back the trunk liner to access the VCIM. It is typically not fastened down, allowing for easy access.
6. Disconnect the wiring harnesses from the VCIM. Be careful with the plastic locking tabs.
7. Remove the module from the vehicle and open the battery access door.
8. Replace the old battery pack with the new one. It is a direct plug-in replacement.
9. Reassemble the module, reinstall it in the vehicle, and reconnect its wiring harnesses.
10. Reconnect the negative terminal of the main vehicle battery.
11. Clear the trouble codes with the scan tool. Start the vehicle; the OnStar light should initialize and turn green. A current B1446 code will clear on its own once the VCIM detects the new battery's voltage is above the threshold.

Parts You'll Likely Need

• OnStar Backup Battery (OEM #25793893 (Superseded by other numbers)) — This is a non-rechargeable battery with a finite life that is the direct cause of code B1446. The entire OnStar module (VCIM) for this vehicle may be found under part numbers like 22704633, but only the internal battery needs replacement.
  Trusted brands: ACDelco, Dorman
  OEM price range: $35-$60
  Aftermarket price range: $20-$40

Related Codes That Often Appear With This One

• B1447 — B1447 indicates a complete 'Backup Power Source Open Circuit,' which is a more severe state of the same failure. B1446 is for low voltage, while B1447 means no voltage is detected at all.

Technical Service Bulletins (TSBs) & Recalls

• PIC4541F: Diagnostic tip for OnStar back-up battery failure resulting in DTC B1446 or B1447 and a red OnStar LED.
• PIC4541E: An earlier version of the same TSB, which lists a wide range of affected GM vehicles and explains that the backup battery (BUB) is not rechargeable and will be permanently drained if activated.

Platform-Specific Known Issues

• A GM Technical Service Bulletin (PIC4541F) directly addresses this code. It warns technicians to never disconnect the main vehicle battery or remove the OnStar fuse with the ignition key in any position other than OFF. Doing so can trigger the backup battery system, permanently discharging it and requiring its replacement.
• The VCIM location in the 9th generation Impala is in the trunk, on the driver's side behind the liner. This is a consistent location for this model year range.

Mechanic-Grade Diagnostic Values

• VCIM Backup Battery Circuit Voltage — expected: Greater than 15.5 V. Failure: A reading less than 15.5 V indicates a potential open/high resistance in the wiring or a failed backup battery.
• Main System Voltage (for DTC test to run) — expected: Between 9.5 V and 15.5 V. Failure: If system voltage is outside this range, the B1446 diagnostic will not run.

Scan Tool Commands That Help

• Tech 2 (2008 and prior) / GDS2 with MDI (2009+): VCIM Vehicle Communication Interface Module Set-up — This function is required after replacing the OnStar VCIM to program the new module specifically for the vehicle it's installed in.
• Tech 2 (2008 and prior) / GDS2 with MDI (2009+): ONSA (OnStar Activation) — This is the second required step after a VCIM replacement. It gathers data from the new module and sends it to OnStar to update the subscriber's account and activate the unit.

Wiring & Ground Locations

• VCIM Connector X1, Pins 13 & 14 — On the main connector (X1) of the OnStar module (VCIM) located in the trunk.. These are the specific pins to test for voltage from the backup battery circuit. A low reading here confirms a circuit or battery issue.
• G301 — On the floor, to the left of the driver's seat.. This is a primary ground point for vehicles equipped with OnStar. A poor connection here could cause various electrical issues with the system, although it is a rare cause for B1446.

Real Owner Repair Stories

• Chevrolet Forum user (Chevrolet Impala (year not specified, but within range)) — Dead OnStar backup battery.
  ❌ Tried (didn't work) Getting quotes from dealers.
  ✅ What actually fixed it User purchased the battery (GM part number 88861186) online and installed it themselves in 10 minutes after locating the module in the trunk on the driver's side.
• Car Talk Community user (2007 Chevrolet Impala LT) — Solid red light on the rearview mirror.
  ✅ What actually fixed it The user pushed the OnStar button, and an advisor ran a remote diagnostic, confirming a failing/failed OnStar back-up battery. The user was scheduled for a dealer replacement. This confirms the system can self-diagnose and report the failure remotely.
• 2CarPros user (2008 Chevrolet Impala) — User wanted to permanently disable the OnStar system for privacy.
  ❌ Tried (didn't work) Pulling the 10A OnStar fuse.
  ✅ What actually fixed it The user located the VCIM in the trunk on the driver's side behind the carpet liner, disconnected the two wiring harnesses, and unplugged the separate lithium battery pack to completely disable the unit. This confirms the component layout for a DIY repair.

When the Usual Fixes Don't Work

• While replacing the backup battery is the standard and most common fix for B1446, there are documented cases where this does not resolve the issue. If a new battery is installed and the red OnStar light persists with code B1446, it strongly suggests an internal failure of the Vehicle Communication Interface Module (VCIM) itself. The module's internal circuitry that reads the battery voltage can fail, causing it to report a low voltage condition even with a perfectly good battery. In this scenario, the only solution is to replace the entire VCIM, which then requires dealer or specialist programming to link it to the vehicle.

OEM Part Supersession History

• 88861186 → 25793893, 23277647 — Standard part number updates and supplier changes over time.
  Heads up: These part numbers are generally interchangeable for this application. Always verify with the supplier using the vehicle's VIN.

Model Year Variations Within This Range

• 2006-2008 vs 2009-2013: The service procedure for setting up a replacement OnStar module (VCIM) changed. For 2008 and prior models, setup and activation were performed using a Tech 2 scan tool. For 2009 and newer models, the procedure was moved to the Service Programming System (SPS) application, used with an MDI or other J2534 interface.