B3055 on 2007 Buick Terraza: No-Start, Security Light Causes and Fixes

What's Unique About the 2007-2007 Buick TERRAZA

The Buick Terraza and its GM U-body platform mates from this era (Chevrolet Uplander, Pontiac Montana SV6, Saturn Relay) use the Pass-Key III (PK3) immobilizer system. This system is known for issues with the ignition lock cylinder and the transponder keys, as documented in manufacturer TSBs like #PIC5650M, which specifically mentions a no-crank or stall condition with code B3055. The failure is almost always within the key or the ignition cylinder's reader (exciter coil), not a more complex computer issue.

Diagnostic Flowchart

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

Symptoms You May Notice

• Engine will not crank or turn over
• Engine starts briefly and then immediately stalls
• Security light is flashing or stays on solid on the dashboard.
• A "Service Theft System" or similar message may appear on the driver information center.

Most Likely Causes

1. Faulty or Damaged Ignition Key 🔴 High Probability → Shop Ignition Switch The transponder chip inside the key head can be damaged from being dropped, exposure to moisture, or simply fail with age. The key itself can also become worn, causing intermittent contact.
   How to confirm: Try starting the vehicle with a known-good spare key. If the spare key works consistently, the original key is faulty.
   Typical fix: Replace the faulty key. A new key must be cut and then programmed to the vehicle using a specific relearn procedure. This can be done by a dealer or an automotive locksmith.
   Est. part cost: $50-$150
2. Faulty Ignition Lock Cylinder / Exciter Coil 🔴 High Probability → Shop Ignition Switch The exciter coil that surrounds the ignition cylinder energizes and reads the key's transponder. The thin wires for this coil can break from the repeated stress of turning the key or from heavy keychains, leading to a loss of signal.
   How to confirm: If all available keys fail to start the vehicle, and the battery is confirmed to be good, the ignition lock cylinder assembly is the most likely culprit. A technician can test for continuity on the signal wires between the cylinder and the BCM using a wiring diagram.
   Typical fix: Replace the ignition lock cylinder assembly. This part often includes the cylinder, housing, and the transponder reader coil. A security relearn procedure is required after installation.
   Est. part cost: $50-$250
3. Low Vehicle Battery Voltage 🟡 Medium Probability → Shop Vehicle Battery A weak or dying battery can cause a multitude of seemingly unrelated electronic issues, including causing the BCM to fail to read the key properly and falsely setting security codes. The security modules are sensitive to low voltage.
   How to confirm: Test the vehicle's battery with a multimeter. A healthy, fully charged battery should read at least 12.4 volts. Perform a load test to confirm its health. If it's low, charge and re-test it. If it won't hold a charge, replace it.
   Typical fix: Charge or replace the vehicle's 12V battery. It's recommended to connect a battery charger when performing relearn procedures to ensure stable voltage.
   Est. part cost: $150-$250
4. Radio Frequency (RF) Interference ⚪ Low Probability Other keys with transponders, building access cards, gas station payment fobs, or even some aftermarket phone chargers can emit radio frequencies (commonly 125 kHz) that interfere with the communication between the key and the vehicle.
   How to confirm: Remove all other keys, fobs, and cards from the keychain. Try to start the vehicle with only the single Terraza key present. If the vehicle starts, one of the other items was causing interference.
   Typical fix: Keep other RFID-enabled devices separate from the ignition key when starting the vehicle.
   Est. part cost: $0

Rare But Worth Checking

• Faulty Body Control Module (BCM): → Shop Body Control Module While possible, the BCM is rarely the cause of this specific code. It should only be considered after all other possibilities, including keys, the ignition cylinder, and wiring, have been definitively ruled out. BCM replacement requires professional programming.
• Damaged Wiring: The wires running from the ignition lock cylinder down the steering column to the BCM can become chafed, pinched, or broken, causing an intermittent connection. This is less common than component failure but worth inspecting if the problem is intermittent, especially if the steering column has been previously serviced.

Diagnosis Steps

1. Check the vehicle's battery voltage to ensure it is above 12.4V. Charge or replace if necessary. A battery charger should be connected during diagnostics to ensure stable voltage.
2. Remove all other keys, fobs, and RFID cards from the keychain to eliminate potential radio frequency interference.
3. Attempt to start the vehicle with a known-good spare key. If the vehicle starts, the primary key is defective.
4. If no keys work, attempt the 30-Minute Security Relearn Procedure. This can sometimes clear a software glitch.
5. Detailed Relearn Procedure: 1. Turn the key to 'ON' (do not start). 2. Wait for the security light to turn off (this takes approx. 10-11 minutes). 3. Turn the key 'OFF' for 10-30 seconds. 4. Repeat steps 1-3 two more times for a total of three cycles. 5. After the third cycle, turn the key off, then try to start the engine. The vehicle should now start.
6. If the relearn procedure fails, inspect the wiring harness and connector at the ignition lock cylinder for visible damage, looseness, or chafing.
7. If wiring appears intact, the most likely cause is a failed ignition lock cylinder/exciter coil assembly. Replacement is the next step.
8. If replacing the lock cylinder does not resolve the issue, the Body Control Module (BCM) may be at fault, which requires advanced diagnostics by a professional using a scan tool like a GM Tech 2.

Parts You'll Likely Need

• Ignition Lock Cylinder (OEM #15785106) — This assembly contains the exciter coil that reads the key's transponder chip. The internal wiring is a common failure point, causing the B3055 code and a no-start condition.
  Trusted brands: ACDelco, Standard Motor Products (US587)
  OEM price range: $55-$90
  Aftermarket price range: $35-$70
• Transponder Ignition Key — The electronic chip embedded in the key head can fail, preventing it from sending the required security code to the vehicle. This is confirmed by trying a spare key.
  Trusted brands: ACDelco
  OEM price range: $40-$80
  Aftermarket price range: $20-$50

Related Codes That Often Appear With This One

• B3060 — This code for 'Unprogrammed Transponder' can appear with B3055 if the BCM detects a key signal but doesn't recognize it, which can happen during a system fault or programming failure.
• B3935 — Meaning 'Transponder Authentication Failed,' this code indicates the key's signal was received but was incorrect. It can be set alongside B3055 during a security system fault.
• B2955 — This code for 'Security Sensor Data Circuit Malfunction' can be set when there's a problem in the wiring between the ignition lock cylinder's exciter coil and the BCM, which would also prevent the key from being read and trigger B3055.

Technical Service Bulletins (TSBs) & Recalls

• PIC5650M: Addresses an intermittent no crank, no start, or start stall concern with the security light coming on, specifically listing B3055 as a potential diagnostic trouble code for this platform.
• PIT5030E: While for newer models, this TSB explains how a flip-style key not being fully extended can cause a B3055. This principle of key position being critical can apply to worn standard keys as well.

Platform-Specific Known Issues

• As per TSB #PIC5650M, the 2007 Buick Terraza and its platform mates are known to exhibit intermittent no-crank, no-start, or stall conditions accompanied by the security light and code B3055.
• Owners on forums for the Chevrolet Uplander and Pontiac Montana SV6 frequently report this exact issue, with the ignition lock cylinder/switch being the most common successful repair after trying spare keys.

Mechanic-Grade Diagnostic Values

• Theft Deterrent Exciter Coil Resistance — expected: While specific values for the Terraza are not published, general GM Pass-Key III systems should have a resistance between 18-24 Ohms.. Failure: A reading significantly outside this range, or an open circuit (OL), indicates a failed exciter coil within the ignition lock cylinder assembly.
• BCM Ground Circuit Resistance — expected: Less than 2.0 Ohms. Failure: Resistance higher than 2.0 Ohms indicates a poor ground connection, which can cause various BCM-related issues including false anti-theft codes.

Scan Tool Commands That Help

• GM Tech 2: Data Display > BCM > Immobilizer Data — Use this function to view live data related to the Pass-Key system. Look for parameters like 'Key State' or 'Transponder Status' to see if the BCM is detecting a key at all, if it sees it as valid, or if it's getting no signal.
• GM Tech 2: Special Functions > BCM > Program New Keys — This is the professional method for programming new keys after replacing a key or the ignition lock cylinder. It is faster and more reliable than the 30-minute manual relearn procedure.

Wiring & Ground Locations

• Body Control Module (BCM) — Located to the left of the steering column, often above the driver's kick panel.. The BCM is the central module for the Pass-Key III anti-theft system. All signals from the ignition key's transponder are processed here. Wiring faults between the ignition cylinder and the BCM are a potential cause of B3055.
• G201 — On the left side of the dash support beam, above the BCM.. This is a primary ground point for multiple instrument panel components, including the BCM. A loose or corroded G201 can cause intermittent BCM failures and set false diagnostic codes like B3055.
• Ignition Switch Connector — On the steering column, connected to the ignition lock cylinder housing.. This connector contains the two signal wires from the Pass-Key exciter coil to the BCM. Probing for continuity and resistance at this connector is a key diagnostic step.
• BCM Connector C1 (Black 52-Pin) — Plugged into the BCM, which is left of the steering column.. This connector contains the primary ignition and power feeds for the BCM. Specifically, Pin 22 (Pink wire) is Ignition 1 Voltage, which powers the module during a start attempt.

OEM Part Supersession History

• 12457103 → 15785106 — Part has been updated or revised by the manufacturer.