B3055 on 2010-2017 GMC Terrain: Causes for No-Start & Security Light

What's Unique About the 2010-2017 Gmc TERRAIN

The first-generation GMC Terrain (2010-2017) and its sibling, the Chevrolet Equinox, frequently use a switchblade-style key. A well-documented issue, highlighted in GM Technical Service Bulletin PIT5030E, is that if this key is not fully locked in the straight-out position, it can cause a B3055 code and a no-start condition. The transponder chip is located in the fob portion of the key, and if the blade is angled, the chip may be too far from the reader coil around the ignition cylinder to be read properly. This simple mechanical issue is often the root cause, making it a unique and crucial first check for this specific vehicle before assuming component failure.

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 or start.
• Engine starts briefly and then immediately stalls.
• Security or anti-theft light is illuminated or flashing on the instrument cluster.
• A "Key Not Detected" or "Service Theft Deterrent System" message may a 🎬 Watch: How to reset the GMC Terrain theft deterrent system.ppear on the driver information center (DIC).

Most Likely Causes

1. Ignition Key Not Fully Extended 🔴 High Probability The switchblade key design allows it to be inserted while partially folded, moving the transponder chip out of range of the ignition's reader coil. This is a widely known issue for this platform.
   How to confirm: Remove the key, ensure it is fully clicked open and locked straight. Re-insert and try to start the vehicle. If it starts, this was the cause. This is explicitly detailed in TSB PIT5030E.
   Typical fix: User education. Always ensure the key is fully extended before use. The TSB advises dealers to share this information with the customer.
   Est. part cost: $0
2. RFID Interference 🟡 Medium Probability As noted in TSB PIC5650M and its successors, other RFID-enabled cards or fobs on the same keychain (e.g., office key cards, gas station fobs, other car keys) can interfere with the 125 kHz signal from the ignition key.
   How to confirm: Remove all other keys and electronic devices from the GMC key ring and try to start the vehicle again. If the issue resolves, interference was the cause.
   Typical fix: Keep the ignition key on a separate ring from other RFID-enabled devices. TSB PIC5650 series also warns against aftermarket USB chargers and LED lights which can create RFI.
   Est. part cost: $0
3. Defective or Damaged Ignition Key 🟡 Medium Probability
   How to confirm: Try starting the vehicle with a spare key. If the spare key works consistently, the original key's internal transponder chip is likely faulty. This can happen from being dropped or from internal component failure. A technician on YouTube demonstrated cloning a super chip and placing it inside the key fob to resolve an intermittent transponder issue on a 2013 Equinox.
   Typical fix: Replace and program a new ignition key. This requires a locksmith or dealership with the proper programming tools. 🎬 See this tutorial on adding a new flip-key yourself. A new key can also be cloned from the old one if the transponder can still be read intermittently.
   Est. part cost: $75-$250
4. Faulty Ignition Lock Cylinder / Transponder Reader ⚪ Low Probability
   How to confirm: If multiple known-good keys fail to start the vehicle, and there is no RFI, the problem may be the reader coil (exciter coil) around the ignition cylinder. A technician can test the coil's function and wiring.
   Typical fix: Replace the ignition lock cylinder assembly, which includes the transponder reader coil. This part will need to be programmed to the vehicle.
   Est. part cost: $150-$300
5. Failing Body Control Module (BCM) ⚪ Low Probability
   How to confirm: This is a diagnosis of last resort after all other possibilities (key, interference, wiring, reader coil) have been ruled out. A failing BCM often presents with multiple, seemingly unrelated electrical issues, such as erratic lights, door lock problems, or parasitic battery drain. A scan tool may also show communication codes (U-codes) with other modules.
   Typical fix: Replace and program the Body Control Module. This is an expensive repair that must be done at a dealership or qualified shop with access to GM programming software.
   Est. part cost: $400-$800

Rare But Worth Checking

• Low Vehicle Battery Voltage:

Diagnosis Steps

1. Verify the battery is fully charged (above 12.4V) and the terminals are clean.
2. Remove the key from the ignition. Make sure it is fully extended and locked straight, per TSB PIT5030E.
3. Remove all other keys, fobs, and RFID cards from the key ring to eliminate RFI, per TSB PIC5650M.
4. Re-insert the GMC key and attempt to start the engine.
5. If the vehicle still does not start, try the spare key. If the spare key works, the primary key is faulty.
6. If neither key works, scan the BCM for codes B3055, B3060, and B3935.
7. If a scan tool is available, check the BCM data stream to see if a 'Key Part Number' is being recognized when the key is turned on. If not, it points to a key or reader issue.
8. Inspect the wiring and connector at the ignition lock cylinder for any damage or loose connections.
9. If wiring is good and keys are not the issue, the ignition lock cylinder's reader coil or the BCM are the next components to test professionally.

Parts You'll Likely Need

• Ignition Key with Transponder (OEM #20835402) — The transponder chip in the original key may have failed or been damaged. Trying a spare key is the easiest way to confirm this. This part number is for the 3-button flip key remote.
  Trusted brands: ACDelco, Strattec
  OEM price range: $100-$180
  Aftermarket price range: $50-$100
• Ignition Lock Cylinder with Transponder Reader — If multiple known-good keys won't work, the reader coil that surrounds the ignition cylinder may have failed, preventing it from energizing and reading the key chip. This part often comes with new, uncoded keys that must be programmed.
  Trusted brands: ACDelco, Dorman
  OEM price range: $200-$350
  Aftermarket price range: $100-$200

Related Codes That Often Appear With This One

• B3060 — This code, 'Uncalibrated or Mismatched Immobilizer Key,' often appears with B3055 and points to a general failure in the key-reading process. TSB PIC5650M lists it as a common related code.
• B3935 — This code indicates a 'Transponder Authentication Error' and is another common partner to B3055, confirming the issue is within the Pass-Key III+ immobilizer system. TSB PIC5650M also lists this code.

Technical Service Bulletins (TSBs) & Recalls

• PIC5650M: Mentions intermittent no crank/no start with security light and DTCs B3055, B3060, and B3935. Discusses potential RFID interference from other keys, toll passes, and even aftermarket electronics like LED lights and phone chargers.
• PIT5030E: Specifically identifies the switchblade key not being fully extended as a cause for an intermittent no-crank and setting DTC B3055. Includes pictures showing the correct and incorrect key positions.

Platform-Specific Known Issues

• Per TSB PIC5650M, this vehicle can experience an intermittent no crank, no start, or start/stall with the security light on, which sets DTC B3055. The cause is often Radio Frequency Interference (RFI) from other devices on the keychain or in the car.
• Per TSB PIT5030E, a common cause for this code is the switchblade key not being fully extended, which prevents the transponder from being read correctly. The bulletin explicitly instructs technicians to educate customers on this point.

Mechanic-Grade Diagnostic Values

• Resistance of BCM ground circuit — expected: Less than 10 ohms. Failure: Greater than 10 ohms indicates an open or high resistance in the ground circuit.
• Voltage at BCM signal circuit (at BCM connector) — expected: Less than 1 V with key ON, engine OFF. Failure: Voltage greater than 1V indicates a short to voltage in the circuit.
• Resistance of immobilizer signal circuit — expected: Less than 2 ohms end-to-end. Failure: Resistance greater than 2 ohms points to an open or high resistance in the signal wire between the BCM and the transponder reader.

Hidden / Shadow Codes Worth Checking

• B3055 00: The '00' is a symptom byte indicating 'No Sub Type Information'. This means the primary code 'B3055' contains all the necessary fault information, specifically 'No Transponder Modulation or No Transponder'. (see via A professional scan tool like GM's GDS2 or a high-end aftermarket scanner will display the code with its symptom byte.)

Scan Tool Commands That Help

• GDS2 / Tech2: Immobilizer Learn — This function is required after replacing a key, the ignition lock cylinder, or the Body Control Module (BCM) to program the new components to the vehicle's immobilizer system.
• GDS2 / Tech2: BCM Data Display: 'Key Part Number' — When diagnosing a no-start, monitor this parameter while inserting and turning each key. If the parameter remains blank or shows 'Not Present' for a specific key, that key's transponder is faulty. If it's blank for all keys, the issue is likely the reader coil or BCM.
• GDS2 / Tech2: Clear All DTCs — After a repair (like replacing a key or simply straightening a bent key), all codes should be cleared. For this specific issue, TSB PIT5030E recommends clearing the B3055 from history and re-verifying all learned keys operate correctly.

Wiring & Ground Locations

• BCM (Body Control Module) — Located under the driver's side of the dashboard. Some fuses are also located in a panel on the passenger side center console.. The BCM is the central module for the Pass-Key III+ immobilizer system. It reads the key data from the transponder reader and enables or disables starting.
• BCM Connector C3 (or X3) — This is one of the main connectors at the Body Control Module under the driver's dash.. Pin 22 (White with Black stripe wire) is a key data line for the immobilizer system on some diagrams. Pin 6 (Pink) is an ignition voltage feed.
• BCM Connector C4 (or X4) — Another main connector at the BCM.. Pin 26 (Black with White stripe wire) serves as a ground for the BCM. A poor ground here can cause a wide range of issues, including immobilizer faults.
• G112 — This is a common engine ground point. On the 3.6L V6, there are multiple ground connections on the engine block itself.. While not directly part of the BCM-to-key circuit, a poor engine or chassis ground can cause communication errors between the BCM and the Engine Control Module (ECM), which can mimic or contribute to immobilizer system faults.
• Data Link Connector (OBD-II Port) — Under the driver's side dashboard, near the left shin area.. This port's power is supplied by fuse F36 (7.5A) in the interior fuse panel (passenger side). If the scan tool won't power on, this fuse is the first place to check.

Real Owner Repair Stories

• YouTube channel 'Hands On Auto Training' (2015 Chevrolet Malibu (similar GM platform)) — No crank, no start. Security light was on. Scan tool showed active code B3055 'No Transponder Modulation'.
  ❌ Tried (didn't work) Clearing the code resulted in it immediately returning. The original key would not allow the car to start.
  ✅ What actually fixed it The technician diagnosed a bad transponder chip within the original key. Using an Autel Pro Pad, they performed the 'Immobilizer Learn' procedure to program a brand new key to the vehicle. After the 10-minute security wait time, the new key started the car successfully.
• YouTube channel 'ADD AUTOMOBILE SERVICES' (2013 Chevrolet Equinox (platform sibling)) — Intermittent no start with security light staying on. Code B3055 was present, indicating 'no transponder'.
  ❌ Tried (didn't work) The original key worked intermittently. When it failed, the car would not crank.
  ✅ What actually fixed it The technician used a VVDI key tool to read the intermittent original key's transponder data. They then cloned this data onto a new 'super chip' and placed that new chip inside the original key fob. The cloned chip provided a reliable signal, permanently fixing the intermittent starting problem.

Model Year Variations Within This Range

• 2010-2017: The interior fuse box layout and some fuse assignments changed slightly between 2010, 2011-2012, and 2013-2017. For example, the BCM is powered by multiple fuses (BCM 1, BCM 2, BCM 3, etc.) and their specific numbers in the panel may vary by year. Always refer to the diagram for the specific model year.