B1447 on 2013-2017 Cadillac XTS: OnStar Backup Battery Failure Causes and Fixes

What's Unique About the 2013-2017 Cadillac XTS

This is a very common and expected failure on many GM vehicles from this era built on the Epsilon II platform, including the Cadillac XTS, Buick LaCrosse, and Chevrolet Impala. The OnStar backup battery is a non-rechargeable, consumable part with a finite service life, typically lasting 3-7 years. Its failure is documented in GM Technical Service Bulletin PIC4541F, which covers a wide range of models including the XTS. The failure is a matter of when, not if, for most owners.

Diagnostic Flowchart

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

Symptoms You May Notice

• Red light illuminated on the OnStar button assembly (on the mirror or overhead console).
• "Service OnStar" message on the Driver Information Center (DIC)
• Inability for the OnStar system to connect
• Check Engine Light or Service Vehicle Soon light may be active
• Audible voice from OnStar stating the system needs service upon vehicle startup.

Most Likely Causes

1. Failed OnStar Backup Battery 🔴 High Probability → Shop Vehicle Battery The battery is a non-rechargeable lithium unit with a limited chemical lifespan of 3-7 years. After several years of service, it naturally degrades and fails, which is an expected maintenance event across the GM Epsilon II platform.
   How to confirm: Confirm the presence of code B1447 or B1446 with a capable OBD-II scanner that can read Body (B) codes. The solid red OnStar indicator light is the most common and definitive visual confirmation. A professional scan tool may show a symptom byte of '04' for an open circuit.
   Typical fix: Replace the OnStar backup battery module. The module is located in the trunk on the driver's side, behind the carpeted trim panel.
   Est. part cost: $60-$120

Rare But Worth Checking

• Wiring Harness or Connector Issue: Although rare for this specific code, the wiring leading to the OnStar module (VCIM) could be damaged or the connector could be loose. A common area for wiring damage on the XTS is the harness that runs along the trunk hinge, which can fray over time and cause various electrical issues. This is worth checking during battery replacement.
• Failed Vehicle Communication Interface Module (VCIM): → Shop Telematics Interface Module In very rare cases, the OnStar module itself may fail in a way that it can no longer correctly read the status of its backup battery. This should only be considered after a new battery fails to resolve the code. A failing VCIM may also set other communication codes like U0198. Replacement of the VCIM requires professional programming.

Diagnosis Steps

1. Verify the complaint: Check for a red light on the OnStar buttons and a 'Service OnStar' message.
2. Scan for codes using an OBD-II scanner capable of reading Body (B) codes to confirm B1447 and/or B1446 is present.
3. CRITICAL: Turn the ignition completely OFF. Remove the key from the ignition. Open and then close the driver's door to cancel Retained Accessory Power (RAP). Wait at least 2-3 minutes for all modules to power down completely. Failure to do this will destroy the new battery upon installation.
4. Open the trunk. On the left (driver's) side, remove the plastic trim clips holding the carpeted liner in place. A trim removal tool is recommended to avoid breaking the clips.
5. Peel back the trunk liner to expose the OnStar VCIM module and its attached backup battery. The battery is a small black box connected to the main module.
6. Disconnect the electrical connector from the backup battery.
7. Remove the old backup battery from its mounting bracket. It may be held by clips or small screws.
8. Install the new backup battery into the bracket.
9. Reconnect the electrical connector to the new battery.
10. Re-secure the trunk liner with its clips.
11. Turn the ignition on. The red OnStar light should now be off (it may be green or off entirely). Clear the trouble codes with the scan tool. The code may clear on its own after 50 consecutive malfunction-free ignition cycles, but using a scanner is immediate. If the code does not return, the repair is complete.

Parts You'll Likely Need

• OnStar Backup Battery Module (OEM #23117460, 84545218) — This is the component that fails and directly causes the B1447 code. It is a non-rechargeable, consumable part with a limited lifespan. Part number 23117460 is widely cited, with 84545218 being a potential newer or alternative number.
  Trusted brands: ACDelco, GM Genuine Parts, Ultralife
  OEM price range: $60-$120
  Aftermarket price range: $40-$70

Related Codes That Often Appear With This One

• B1446 — B1446 is an alternate code for the same OnStar backup battery failure, specifically indicating 'Backup Power Source Voltage Below Minimum Threshold'. GM TSB PIC4541F lists both B1446 and B1447 as indicators of this issue, likely representing slightly different failure modes (e.g., low voltage vs. open circuit).

Technical Service Bulletins (TSBs) & Recalls

• PIC4541F: Provides diagnostic tips for OnStar back-up battery failure indicated by DTC B1446 or B1447 and a red OnStar LED. Critically, it warns to let Retained Accessory Power (RAP) time out before disconnecting power to the VCIM to avoid destroying the new, non-rechargeable battery.

Platform-Specific Known Issues

• GM issued Technical Service Bulletin PIC4541F specifically to address this issue. It warns technicians that disconnecting power from the OnStar module while the ignition or Retained Accessory Power (RAP) is active will trigger the new battery, permanently discharging it. The battery is not rechargeable and will be ruined.
• A less common but possible issue on the XTS is damage to the trunk wiring harness where it flexes near the hinge. A Reddit user with a 2019 XTS traced a trunk latch failure to a broken wire in this exact spot, demonstrating a potential vulnerability in that area that could, in theory, affect the OnStar module wiring.

Mechanic-Grade Diagnostic Values

• Voltage between the backup battery supply voltage circuit (terminal 14 at the VCIM connector) and ground. — expected: 15.5 volts or greater.. Failure: A reading less than 15.5 volts indicates a short to ground or an open/high resistance in the supply circuit, assuming the battery itself is good.

Hidden / Shadow Codes Worth Checking

• B1447 04: Backup Power Source Open Circuit. This is the most common symptom byte and directly indicates the VCIM sees no voltage from the battery, usually due to internal battery failure. (see via A professional GM-specific scan tool like a Tech2 or GDS2 is required to view symptom bytes.)
• B1447 07: Backup Power Source Component Protection Timeout Voltage Above Threshold. This is a less common variant that could point to a short to voltage in the wiring harness. (see via A professional GM-specific scan tool like a Tech2 or GDS2 is required to view symptom bytes.)

Scan Tool Commands That Help

• GDS2/Tech2 (via TIS2web): VCIM Replace and Reprogram — This function is mandatory ONLY if the entire OnStar module (VCIM) is replaced, not for a simple battery swap. It programs the new module to the vehicle's VIN and configuration.
• GDS2/Tech2 (via TIS2web): Programming and Service Activation — This is part of the VCIM replacement process. It activates the newly programmed module with the OnStar network. Failure to perform this step will result in a non-functional system with a red LED, even with a new module.
• Any capable OBD-II Scanner: Clear DTCs — After replacing the backup battery, the stored B1447 code must be cleared from the VCIM. While the code may clear on its own after 50 good ignition cycles, using a scan tool is the immediate and recommended method to verify the repair.

Wiring & Ground Locations

• Telematics Communication Interface Control Module (VCIM) — On the rear package deck (the shelf behind the rear seats), accessible from the trunk.. This is the main OnStar computer that houses the backup battery. Knowing its precise location is essential for the repair.
• G401 — Located on the left side of the luggage compartment (trunk).. This is a primary ground point in the trunk. A loose or corroded G401 could potentially cause communication or power issues for the nearby OnStar module, mimicking other failures.
• Instrument Panel Fuse Block — Behind the storage compartment to the left of the steering wheel.. This fuse block contains the fuse for the OnStar/Telematics system. Its location varies by model year.

OEM Part Supersession History

• 23117460 → 84545218 — Standard part evolution or manufacturer change.
  Heads up: Part number 23117460 is widely cited for this generation. 84545218 is often listed as a direct replacement or alternative. Both are generally considered compatible for the 2013-2017 XTS, but it is always best practice to confirm fitment with the vehicle's VIN.

Model Year Variations Within This Range

• 2013-2015 vs. 2016-2017: The fuse location for the OnStar/Telematics module in the instrument panel fuse block changed. For 2013-2015 models, it is fuse #1. For 2016-2017 models, it is fuse #20.
• 2013-2017: All vehicles in this range were equipped with OnStar modules using 2G or 3G CDMA cellular technology. As of 2022, these networks have been decommissioned in the United States, rendering the original OnStar hardware non-functional for communication services, though the system can still set fault codes like B1447.