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Anti-Theft Circuit

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Old Mar 28, 2025 | 11:40 PM
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Default Anti-Theft Circuit

Hey. According to this anti theft diagram the BCM has to interpret something from the doors and hatch (maybe that they're closed) too work and if this signal is not sent the car won't start yes or no? If yes, if the wires are cut (like mine are) then I need to locate and ground these wires (gry/blk, blk/wht and org/blk) in order to complete the circuit and theoretically if everything else fine the car should turn over?

Jo




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Old Mar 29, 2025 | 01:08 PM
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Those connections are used only for the optional alarm (Content Theft Deterrent) system. They determine when to trigger the alarm if it has been armed. If the alarm is not installed or is not activated then they would have nothing to do with the car not starting.
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Old Mar 29, 2025 | 05:09 PM
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Thanks. You answered my question and at the same time prompted another question. Wasn't sure if those affected the start circuit but when I grounded them the security light did go out thus behaving normally. Given it's behavior prior to grounding I'm guessing I do have a CTD and it may be activated so my question is what does it look like and where is it located?

I also tracked down the actual issue which was no power from the relay to the starter. Thought the wire was a straight shot from one to the other and didn't realize there was a connector. Connector along passenger inner fender wasn't connected. Problem solved.

Jo
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Old Mar 30, 2025 | 03:51 PM
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Check the door tag for option code UA6... the code for the optional alarm system. Another indicator is having an alarm LED on top of the dash next to the defroster vent. The alarm circuitry is contained within the BCM. The SECURITY light in the instrument cluster is not directly related to the alarm system as it is an integral part of VATS - the Vehicle Anti Theft System - which prevents the car from starting unless the correct ignition key resistor is used.

It is possible that you have the CTD system and that it was armed and then activated by the door/hatch open circuits, but that would mean that your wiring is hopelessly butchered for some reason (otherwise your lights would be flashing and your horn would be honking) making it doubtful that you could use the normal programming sequence to turn it off.
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