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Q: Replaced ignition switch, now the car won't start.

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It Seems it may be security related. Need to know how to reset security. I think the anti-theft is preventing it from starting. It won't even crank. All other electronics still power up, but no crank or start.security blinks three times intermittently.

My car has 154000 miles.
My car has an automatic transmission.

Chevrolet has something called a (VATS) Vehicle Anti Theft System which uses a resistive chip ignition key system. VATS has a separate module that is called a TDM or theft deterrent module which sends a signal to the ECM (Car’s computer) informing it that there either is or is not a valid key present which will then either allow it to start or not allow it to; depending on whether the key is valid. I would recommend taking it to the Chevy Dealer to have it re-flashed.

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