B1446 on 2014-2017 Chevrolet Corvette: OnStar Backup Battery Failure Guide

What's Unique About the 2014-2017 Chevrolet CORVETTE

The C7 generation Corvette (2014-2019) features a deeply integrated OnStar system, common across many GM vehicles of this era. The backup battery is a non-rechargeable, consumable lithium battery with a finite lifespan. As these vehicles age, battery failure becomes a common, expected maintenance item. The provided NHTSA TSB (PIC4541F) confirms this is a known issue that dealers were alerted to, warning that improper service procedures can easily destroy a new battery.

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 buttons (on the rearview mirror)
• "Service OnStar" message may appear on the Driver Information Center (DIC)
• Inability of OnStar to function if the main vehicle battery is disconnected
• OnStar advisor may report a diagnostic failure of the backup battery if contacted via the blue button

Most Likely Causes

1. Failed OnStar Backup Battery 🔴 High Probability → Shop Vehicle Battery The backup battery is a non-rechargeable lithium battery that naturally degrades over a period of 5-7 years. This is a normal wear-and-tear item, and its failure is expected as the vehicle ages.
   How to confirm: The presence of code B1446 combined with a red OnStar LED is the primary confirmation. There is no practical way to test the old battery; replacement is the standard diagnostic step.
   Typical fix: Replace the OnStar backup battery module (GM Part No. 23117460).
   Est. part cost: $60-$100

Rare But Worth Checking

• Faulty Vehicle Communication Interface Module (VCIM): → Shop Telematics Interface Module This is very rare. If a new, genuine backup battery does not resolve the code, the module itself could be at fault. However, always suspect the battery first.
• Wiring or Connection Issue: A loose connection at the VCIM or backup battery could theoretically cause this code, but it's much less likely than simple battery failure. This would more commonly set a B1447 code for an open circuit.
• Improper Service Procedure: If the main car battery was recently replaced or disconnected while the ignition or Retained Accessory Power (RAP) was active, it can trigger the OnStar backup battery's one-time emergency use mode, permanently draining it. This will cause code B1446 to appear immediately after the service.

Diagnosis Steps

1. Verify the symptom: Check if the OnStar status LED on the rearview mirror is solid red.
2. Scan for codes using an OBD-II scanner capable of reading Body (B) codes. Confirm B1446 is present. A more advanced scanner may show it as 'B1446 03: Replace Backup Power Source Voltage Below Threshold'.
3. Locate the OnStar module (VCIM) and its attached backup battery. In the C7 Corvette, this is located behind the glove box.
4. CRITICAL: Before disconnecting any components, turn the ignition completely OFF. Open and close the driver's door and wait several minutes for the Retained Accessory Power (RAP) to time out completely. Failure to do this can permanently activate and drain the new battery upon installation, as warned in TSB PIC4541F.
5. Remove the glove box assembly to access the VCIM. This typically requires removing several 7mm screws.
6. Carefully disconnect the electrical connector from the backup battery and remove the old battery module from its mounting bracket on the VCIM.
7. Install the new backup battery and reconnect it to the VCIM.
8. Reassemble the glove box and surrounding trim.
9. Start the vehicle. The red OnStar light should turn green after a few moments. Clear the DTC with a scan tool. The code should clear on its own after several successful ignition cycles if a scanner is not available.

Parts You'll Likely Need

• OnStar Backup Battery Module (OEM #23117460) — This is the direct cause of the fault code in the vast majority of cases. It is a non-rechargeable lithium battery that fails with age.
  Trusted brands: ACDelco (GM Genuine)
  OEM price range: $60-$100
  Aftermarket price range: N/A

Related Codes That Often Appear With This One

• B1447 — B1447 indicates 'Backup Power Source Open Circuit'. This can be set along with B1446 if the battery fails completely, is disconnected, or if the module is disconnected improperly during service.

Technical Service Bulletins (TSBs) & Recalls

• PIC4541F: Provides a diagnostic tip for OnStar back-up battery failure, noting that DTC B1446 or B1447 may be present and the OnStar LED will be red. It warns against improper disconnection procedures that can drain the battery.

Platform-Specific Known Issues

• As noted in GM Technical Service Bulletin PIC4541F, it is critical to not disconnect the main battery or OnStar fuse while the ignition is on or Retained Accessory Power (RAP) is active. Doing so can trigger the backup battery's emergency activation, permanently draining it and requiring immediate replacement.
• Access requires removing the glove box. While not difficult, care should be taken not to scratch the trim panels during removal and reinstallation.

Mechanic-Grade Diagnostic Values

• Backup Battery Voltage at VCIM Connector — expected: Greater than 12.3 V. Failure: A reading below 12.3 V indicates a depleted backup battery requiring replacement.

Hidden / Shadow Codes Worth Checking

• B1446 03: This is a GM-specific symptom byte meaning 'Replace Backup Power Source Voltage Below Threshold'. It directly confirms the backup battery has failed its internal voltage test. (see via A professional scan tool like the GM GDS2/MDI or an equivalent tool capable of reading manufacturer-specific body codes and their symptom bytes.)

Wiring & Ground Locations

• Telematics Communication Interface Control Module (OnStar VCIM) — Located in the lower passenger side of the instrument panel, accessible after removing the glove box.. This module is what sets code B1446. The backup battery is physically attached to it.
• VCIM Connectors X1 and X2 — These are the two main multi-pin connectors on the Telematics Communication Interface Control Module.. While a wiring issue is rare, any diagnosis beyond battery replacement would involve testing pins on these connectors. The backup battery voltage is supplied through one of these connectors.
• Main Battery Ground (G303) — A stud on the frame rail in the rear of the vehicle where the main negative battery cable connects.. While not directly related to the OnStar backup battery, a poor main ground can cause a host of unrelated, confusing electrical issues. Ensuring this connection is clean and tight is a good practice during any electrical diagnosis.

OEM Part Supersession History

• 23117460 → 84537658 — Standard part number update by the manufacturer.
  Heads up: The new part number (84537658) is a direct replacement for the old one (23117460) and is fully compatible.