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2022 Yukon Denali Cranks But Won't Start - Security Light Flashing

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Diana O. · rep 0 · May 22, 3:41 AM · 1 replies · solved · Question

Vehicle: 2022 GMC Yukon Denali

Hi all,

My 2022 GMC Yukon Denali, 6.2L V8, is having a major issue. This morning, I went to start it, and it just cranks and cranks but won't fire up. The most concerning thing is that the security light on the dash is flashing rapidly while I'm trying to start it.

I've tried both keys, thinking maybe one was bad, but no luck. The battery seems strong, as it's cranking vigorously. I haven't had any issues with the vehicle before this. It was running perfectly yesterday.

Could this be a PassKey or immobilizer issue? What should I be looking for? I'm stranded and need some guidance.

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 3:41 AM

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ClearTheCode admin answer:

A 'crank but no start' condition combined with a rapidly flashing security light on your 2022 GMC Yukon Denali strongly points towards an issue with the vehicle's anti-theft system, also known as the PassKey or immobilizer system. This system is designed to prevent the engine from starting if it doesn't recognize the key or detects a security breach.

Here's a breakdown of potential causes and diagnostic steps:

  1. Key Fob/Transponder Issue:
    • Damaged Key Fob: Even if the key fob unlocks the doors, the transponder chip inside might be damaged or not communicating correctly with the vehicle's immobilizer. Trying a second, known-good key was a good first step.
    • Key Fob Battery: While less likely to cause a no-start if the vehicle is cranking, a very weak key fob battery can sometimes interfere with transponder communication. Replace the battery in both key fobs.
  2. Immobilizer System Malfunction:
    • Antenna Ring: The antenna ring around the ignition cylinder (or near the push-button start) reads the transponder chip. If this ring is faulty, it won't recognize the key.
    • Immobilizer Control Module: The module itself could be faulty, preventing proper communication or authorization.
    • Wiring Issues: Damaged or corroded wiring related to the immobilizer system can disrupt communication.
  3. ECM/PCM Communication: Sometimes, a communication issue between the Engine Control Module (ECM) or Powertrain Control Module (PCM) and the immobilizer module can cause this. This might be due to a low vehicle battery (even if it cranks, voltage drops during cranking can cause issues) or a module glitch.

When to see a shop:

  • Given the complexity of modern immobilizer systems, this is almost certainly a job for a professional shop or dealership. They have specialized diagnostic tools (like GM's Tech2 or MDI) that can communicate with the immobilizer module, read specific security codes, and perform key relearn procedures.
  • Attempting to bypass or tamper with the immobilizer system can cause further damage and potentially disable other vehicle functions. A professional can accurately diagnose the specific component failure (key, antenna, module) and perform the necessary repairs or programming.
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