B3935 on 2015-2022 GMC Canyon: Security Light and No-Start Causes

What's Unique About the 2015-2022 Gmc CANYON

General Motors has issued multiple, evolving Technical Service Bulletins (TSBs) for the 2015-2022 Canyon and its twin, the Chevrolet Colorado, regarding this specific code. These bulletins, such as PIC5650M, strongly advise technicians *not* to replace any parts initially. The platform's immobilizer system, which operates on 125 kHz, 315 MHz, and 433 MHz frequencies, is highly sensitive to Radio Frequency Interference (RFI). This interference can come from other keys, access cards, aftermarket LED lights, and even cheap USB phone chargers, effectively 'jamming' the signal between the key and the vehicle.

Diagnostic Flowchart

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

Symptoms You May Notice

• Engine does not crank when the key is turned
• Engine starts but stalls immediately
• Security indicator light (a car with a lock symbol) is illuminated or flashing on the dashboard.
• An intermittent no-start condition that cannot be easily replicated.
🎬 Watch: Troubleshooting a Chevy Colorado no-start and no-crank condition.
• "No Remote/Fob Detected" message on the driver information center (for keyless start models).

Most Likely Causes

1. Radio Frequency Interference (RFI) 🔴 High Probability The vehicle's immobilizer system operates on a radio frequency that is susceptible to being 'jammed' by other electronic devices, as noted in GM TSBs PIC5650L and PIC5650M. These bulletins list specific culprits like other car fobs, building access cards, aftermarket LED lighting, and USB chargers.
   How to confirm: Remove all other items from the ignition key ring, including other car fobs, office access cards, gas station payment fobs, and any other electronics. Move aftermarket phone chargers or GPS units away from the ignition area. Try starting the vehicle with just the single Canyon key. If it starts, RFI is the cause.
   Typical fix: Isolate the GMC key from all other electronic devices. Keep other fobs and access cards in your pocket or a bag, not on the same ring as the ignition key.
   Est. part cost: $0
2. Weak or Defective Key 🟡 Medium Probability The battery inside the key fob can weaken over time, or the internal transponder chip can fail. A weak battery may not provide a strong enough signal for the car to read, especially if there is minor RFI present.
   How to confirm: First, try replacing the battery in the key fob (typically a CR2032). 🎬 See this quick guide on replacing your key fob battery. If that doesn't work, try starting the truck with your spare key. If the spare key works reliably, the original key is faulty.
   Typical fix: Replace the key fob battery (CR2032). If the key itself is bad, a new key must be purchased and programmed to the vehicle by a dealer or an automotive locksmith.
   Est. part cost: $5-$15 for a battery, $150-$400 for a new key and programming.
3. Body Control Module (BCM) Software Glitch ⚪ Low Probability → Shop Body Control Module A specific GM bulletin (PI1180A) notes that on some 2015 models, a BCM software issue can cause this code, often alongside B2955, resulting in a 'No Click, No Crank, No Start' condition.
   How to confirm: This can only be confirmed by a GM dealer or a qualified shop with access to GM's Service Programming System (SPS). They will check the current software calibration of the BCM against the latest available updates. The bulletin explicitly states it will not fix a 'Crank-No Start' condition.
   Typical fix: Reprogramming the BCM with the latest software update. This is a dealer or professional-level repair that typically takes about 0.5 labor hours.
   Est. part cost: $0 (software only)

Rare But Worth Checking

• Faulty Immobilizer Antenna (Exciter Ring): → Shop Antenna The antenna ring around the ignition lock cylinder energizes the key's transponder. While it can fail, it is far less common than RFI or key issues. This should only be considered after all other causes are ruled out. The OEM part number is 13523275 for 2015-2018 models.
• Faulty Body Control Module (BCM): → Shop Body Control Module A hardware failure within the BCM itself is possible but very rare. The TSBs specifically advise against replacing modules until all other possibilities, especially RFI, have been exhausted. If a BCM is replaced, it must be programmed to the vehicle.

Diagnosis Steps

1. Verify the security light is on or flashing on the instrument cluster.
2. Remove the ignition key from the key ring. Ensure no other keys, fobs, or access cards are nearby.
3. Unplug any aftermarket devices like phone chargers, dash cams, or LED lights.
4. Attempt to start the vehicle with the isolated key. If it starts, you have found the source of Radio Frequency Interference.
5. If the problem persists, try the spare key. If the spare key works, the primary key is faulty.
6. If the spare key also fails, replace the battery (CR2032) in the primary key fob and re-test.
7. For keyless start models, if the fob is not detected, place it in the dedicated fob pocket/transmitter slot in the center console and attempt to start. If it starts, this points to a weak fob battery or RFI.
8. If all of the above steps fail, the vehicle should be taken to a professional for diagnosis. Mention TSBs PIC5650M and PI1180A to the service advisor, as they may point to a known software or interference issue.

Parts You'll Likely Need

• Key Fob Battery (OEM #CR2032) — A weak battery is a common cause for an intermittent signal from the key's transponder.
  Trusted brands: Energizer, Duracell, Panasonic
  OEM price range: $5-$15
  Aftermarket price range: $2-$10
• Ignition Key / Fob (OEM #13577761, 22881480 (FCC ID: M3N-32337100)) — If the transponder chip inside the key has failed, the entire key assembly must be replaced and programmed.
  Trusted brands: ACDelco (OEM), Strattec
  OEM price range: $150-$250
  Aftermarket price range: $70-$150

Related Codes That Often Appear With This One

• B3055 — This code relates to the key transponder and is often triggered along with B3935 as part of the same security system fault, as cited in multiple GM TSBs like PIC5650M.
• B3060 — Also a security system code related to the transponder, frequently appearing with B3935 due to the same root causes like RFI.
• B2955 — This code, when seen with B3935 on early-year models (primarily 2015), specifically points to a known BCM software issue that requires a dealer reflash per TSB PI1180A.

Technical Service Bulletins (TSBs) & Recalls

• PIC5650M: Mentions B3935 in the context of a no-start/stall condition with the security light on, and lists numerous sources of RFI including aftermarket LED lighting.
• PIC5650L: An earlier version of the bulletin that advises against replacing parts and to investigate Radio Frequency Identification devices as the cause for B3935.
• PI1180A: Points to a BCM software update needed for a no-start condition with DTCs B3935 and B2955 on some 2015 models.

Platform-Specific Known Issues

• GM Technical Service Bulletin #PIC5650M explicitly states that a no-crank or start-stall condition with code B3935 should be investigated for Radio Frequency Identification interference before replacing parts. It lists specific sources like aftermarket LED lights and phone chargers.
• GM Technical Service Bulletin #PIC5650L reinforces this, advising technicians not to replace any parts for this concern until checking for RFI from devices on the customer's keychain.
• A user on coloradofans.com (thread title: 'Intermittent no start, security light flashing') confirmed the RFI fix: 'My 2017 would do this once every few months. Drove me nuts. Dealer told me about the key fob interference. I stopped carrying my other car's fob on the same ring and it hasn't happened in over a year. Such a simple, stupid fix.'

Scan Tool Commands That Help

• GM GDS2/SPS: Vehicle Theft Deterrent (VTD) Relearn — This is mandatory after replacing the Body Control Module (BCM), Engine Control Module (ECM), or ignition key. It synchronizes the security components. A 10-minute or 30-minute manual procedure may also be possible, but the scan tool is the professional method.
• GM GDS2: Module Diagnostics > BCM > Immobilizer Data — To view the status of the immobilizer system, see which keys are programmed, and check the state of the security system. This is a primary step to see what the BCM is reporting.
• GM GDS2: Data Bus Diagnostic Tool — If multiple modules are setting communication codes along with B3935, this tool helps diagnose CAN bus network issues to ensure the BCM can communicate with the ECM and other required modules.

Real Owner Repair Stories

• HR Repair YouTube Channel (2005 GMC Canyon (Note: First generation, but demonstrates the GM security programming principle)) — Customer replaced the BCM with a used part, resulting in a crank but no-start condition and security codes B3031 and B2957.
  ❌ Tried (didn't work) Swapping the BCM with a used unit without reprogramming.
  ✅ What actually fixed it The technician used the GM Service Programming System (SPS) to perform a 10-minute Vehicle Theft Deterrent reprogram. This allowed the new (used) BCM to learn the vehicle's existing key transponders and send the correct fuel enable password to the ECM. The vehicle started and ran correctly immediately after the reprogram.

OEM Part Supersession History

• 13502301, 13504286 → 13523275 — Standard part evolution and consolidation.
  Heads up: Part 13523275 is the immobilizer antenna/exciter ring. It fits 2015-2018 Canyon/Colorado models. While a direct replacement, it requires programming and/or special setup procedures with GM service tools after installation.

Model Year Variations Within This Range

• 2015-2022: This generation uses the GM Pass-Key III+ system, which relies on a transponder chip inside the head of the key. This is fundamentally different from the older 'Passlock' systems used on prior GM generations (like the first-gen Colorado/Canyon), which used a magnet or resistor in the ignition lock cylinder itself. Diagnostic and bypass procedures for Passlock systems are not applicable to these vehicles.