B3925 on 2022 GMC Terrain: 'No FOB Detected', No-Start Causes and Fixes

What's Unique About the 2022-2022 Gmc TERRAIN NA

The 2022 GMC Terrain uses a specific 'GEN3R' Body Control Module (BCM) that is known to be susceptible to memory corruption from low voltage events. This is not unique to the Terrain; its platform-mate, the Chevrolet Equinox, and other GM models like the Blazer, Traverse, and Acadia suffer from the exact same failure mode. General Motors has issued multiple Technical Service Bulletins (TSBs), most notably #23-NA-163, because this issue is so common across its vehicle lineup. Unlike many trouble codes that point to a faulty part, B3925 on this platform almost always points to a software problem that requires a specific reprogramming procedure, not hardware replacement.

Diagnostic Flowchart

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

Symptoms You May Notice

• No-crank, no-start condition
• Engine starts briefly then immediately stalls
• 'No FOB Detected' message on the Driver Information Center (DIC)
🎬 Watch: Troubleshooting a no-start condition on this platform
• Key fobs are inoperative for passive entry and starting (buttons may still work for lock/unlock)
• Unable to shift out of Park
• Multiple warning lights on the instrument cluster (ABS, Traction Control, Check Engine) may appear simultaneously.

Most Likely Causes

1. Body Control Module (BCM) Memory Corruption After Low Voltage 🔴 High Probability → Shop Body Control Module The specific 'GEN3R' BCM used in the Terrain is documented by GM to be susceptible to this software glitch following a voltage drop from a weak battery, jump-start, or battery replacement.
   How to confirm: Using a GM-compatible scan tool, confirm that DTC B389A is present along with B3925 and at least two other codes from the B392x range (B3924, B3926, B3927, B3928). The onset of symptoms will almost always coincide with a recent battery replacement, jump-start, or dead battery event.
   Typical fix: A technician must perform a special BCM software reset and immobilizer relearn procedure using the GM Service Programming System (SPS), as outlined in TSB #23-NA-163. 🎬 See how technicians perform BCM programming using SPS This is a software-only repair. The TSB allows for 0.5 hours of labor time for this procedure.
   Est. part cost: $0

Rare But Worth Checking

• Faulty Passive Entry Passive Start (PEPS) Antenna or Wiring: This is a possible cause only if B3925 appears by itself without the cluster of other codes (B389A, B392x) and is not preceded by a low-voltage event. In this highly unlikely scenario, a hardware fault with an antenna or its circuit could be the cause.
• Short Circuit Frying the BCM: While extremely rare, an unrelated electrical short can physically damage the BCM, causing a no-start and a variety of codes. One owner of a 2018 Equinox reported a loose wire at the rear differential shorted out and destroyed the BCM, requiring a full replacement.

Diagnosis Steps

1. Verify the vehicle's 12V battery is fully charged and in good health. A weak battery is the root cause and must be addressed first. Stable battery voltage is critical for any reprogramming attempt.
2. Connect a professional scan tool (like GM's GDS2) and check the Body Control Module (BCM) for codes.
3. Confirm that DTC B389A is present, along with B3925 and at least two other codes from the B3924-B3928 range.
4. If B389A is not present, the TSB advises disconnecting the battery for at least 30 seconds, reconnecting it, and checking for the code again.
🎬 Watch: A guide to the BCM relearn process
5. If the specific code cluster is present, refer the vehicle to a qualified shop or GM dealer to perform the procedure in TSB #23-NA-163.
6. The technician will use GDS2 to confirm the BCM is a 'GEN3R' type by checking the Base Model Part Number (BMPN). Eligible part numbers include 13519619, 13527252, 13533817, and others listed in the TSB.
7. Using the GM Service Programming System (SPS), the technician will select 'Programming A Per Bulletin 23-NA-163' to reset the BCM software.
8. Immediately following the reprogram, an immobilizer relearn procedure must be performed to re-link the existing key fobs to the BCM.
9. Confirm the vehicle starts, all key fob functions work correctly, and no related DTCs are present.

Parts You'll Likely Need

• 12V Vehicle Battery (OEM #88864541) — A weak or failing battery is the most common trigger for the BCM memory corruption that causes code B3925. The battery must be healthy before the software fix can be applied. Vehicles with start/stop often use a more sensitive AGM-type battery.
  Trusted brands: ACDelco, Interstate, Duralast Platinum
  OEM price range: $250-$350
  Aftermarket price range: $200-$300

Related Codes That Often Appear With This One

• B389A — This is the primary code indicating the BCM has an Environment Identification mismatch. TSB #23-NA-163 states this code will be present with the B392x codes.
• B3924 — Part of the same family of codes indicating an 'Incorrect Environmental Identifier.' It is set along with B3925 during the BCM memory corruption event.
• B3926 — Part of the same family of codes indicating an 'Incorrect Environmental Identifier.' It is set along with B3925 during the BCM memory corruption event.
• B3927 — Part of the same family of codes indicating an 'Incorrect Environmental Identifier.' It is set along with B3925 during the BCM memory corruption event.
• P0513 — This code means 'Incorrect Immobilizer Key.' It can be set because the BCM memory corruption causes it to 'forget' the learned keys, making them appear invalid. [Bulletin #21-NA-277, 2, 4]

Technical Service Bulletins (TSBs) & Recalls

• 23-NA-163: The primary TSB for this issue, it provides a specific software-first repair procedure for a no-start or inoperative key fob condition with DTCs B3924, B3925, B3926, etc., set after a low-voltage event. This TSB has been updated multiple times, with revisions adding more vehicle models like the Chevrolet Blazer and Traverse, confirming the widespread nature of the issue.
• 21-NA-277: An earlier TSB that also addresses the no-crank, no-start condition with these codes, confirming the long-standing nature of this software issue. It applies to vehicles like the Chevrolet Malibu and Equinox.

Platform-Specific Known Issues

• The 2022 GMC Terrain is subject to GM Technical Service Bulletin #23-NA-163, which details a specific condition where a low voltage event causes memory corruption in the Body Control Module, leading to a no-start condition and setting DTC B3925.
• The repair procedure in the TSB is only applicable to vehicles with a 'GEN3R' BCM. A technician must verify the BCM's Base Model Part Number (BMPN) using a scan tool before proceeding. Eligible BMPNs include 13519619, 13527252, 13533817, 13533814, 13527261, and others.

Mechanic-Grade Diagnostic Values

• PEPS Antenna Resistance — expected: Less than 1 ohm between the antenna connector and the cable end.. Failure: Resistance greater than 1 ohm indicates an open circuit in the antenna or its cable, requiring replacement.

Hidden / Shadow Codes Worth Checking

• B3925 00: The '00' is a GM-specific symptom byte meaning 'No Additional Symptom Information.' Its presence alongside B389A and other B392x codes confirms the general BCM memory corruption fault described in TSBs, rather than a more specific sub-system failure. (see via GM GDS2 or other professional-grade scan tools capable of reading manufacturer-specific codes and symptom bytes.)

Scan Tool Commands That Help

• GDS2: BCM Soft Reset — Can be attempted as a first step for a no-crank condition after a low-voltage event. In some cases, this may restore module communication and allow the vehicle to start without a full reprogram.
• GDS2 / SPS: Programming A Per Bulletin 23-NA-163 — This is the primary, specific software fix for the BCM memory corruption issue. It is selected in the Service Programming System (SPS) to flash the BCM with the corrected software.
• GDS2: Immobilizer Learn — This function is required immediately after BCM reprogramming or replacement to re-establish the security credentials between the BCM, ECM, and all vehicle keys.
• GDS2: Request BCM Info for SPS — This function is run before programming a new or existing BCM. It reads the current vehicle configuration and prepares the module for the SPS flashing session.

Wiring & Ground Locations

• K9 Body Control Module (BCM) — Located under the driver's side of the dashboard, to the far left, behind the upper kick panel.. This is the module that sets code B3925 and where all diagnostic and programming work must be performed. A GM bulletin warns to always disconnect the negative battery terminal before disconnecting any BCM ground paths to prevent module damage.
• GM Ground Naming Convention — Vehicle-wide. GM grounds are labeled G1xx (engine bay), G2xx (front passenger area), G3xx (rear passenger area), and G4xx (rear of vehicle). Knowing this helps technicians quickly locate relevant grounds, such as G218 (a common BCM ground point on other GM platforms), when troubleshooting.

Real Owner Repair Stories

• Reddit - r/AutoMechanics (2019 Chevrolet Equinox (platform mate)) — No-start condition with erratic electronic behavior after the battery died.
  ❌ Tried (didn't work) Initial diagnosis was inconclusive.
  ✅ What actually fixed it A technician used a scan tool to perform a 'BCM soft reset.' This restored communication and allowed the vehicle to start. The technician noted that disconnecting the battery for a period might achieve the same result. This highlights a less-invasive software fix that can work before attempting the full TSB reprogram.

Model Year Variations Within This Range

• 2022: The 2022 model year marked a mid-cycle refresh for the GMC Terrain, which included appearance changes and the discontinuation of the 2.0L and diesel engine options. However, the underlying 'GEN3R' BCM and keyless entry system architecture that are susceptible to the B3925 fault remained the same.