Why did a key without a transponder start my 2012 Sierra?

Asked by Apr 20, 2019 at 02:20 PM about the 2012 GMC Sierra 1500 SLE Crew Cab

Question type: Maintenance & Repair

I bought a plain key to unlock the door of my 2012 Sierra and was surprised that it started the truck. I thought only a transponder key would do that. The message, "Service Theft Deterrent System" came up so I killed the engine and restarted it with the right key. Two questions:
1. Why did the plain key start the truck?
2. What would have happened if I continued to drive the truck with the plain key in the ignition?

Thank you for your help!

2 Answers

11,875

Was the factory key on the key ring or close by ? I wouldn't even mess around with T.D.S.'s because to fix it you're going to the dealership ., if it works don't fix it .

200,195

It is possible that the engine would stop after a short distance.

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