The security light is off. Could it still be the theft‑deterrent system?

• Related Articles

• Why Is The Security Light On In My Car?

  On many GM/Isuzu vehicles, a steady or flashing security light usually means the factory immobilizer (Passkey/Passlock/VATS) is seeing a problem with the key, lock cylinder, wiring, or theft‑deterrent module and may start disabling the engine.

• Will I still need a new theft‑deterrent module or BCM?

  If the problem is the factory immobilizer, then no—you do not need a new theft‑deterrent module (TDM) or BCM. The PRO Module is designed as a full bypass of the immobilizer function and, when installed correctly on a supported vehicle, it completely ...

• Should I try servicing the theft‑deterrent system instead of bypassing it?

  You can, but most customers come to us after spending significant money on keys, cylinders and modules that fail again. Our approach is to bypass the failure‑prone system entirely so it can’t strand you again.

• What Does the Security Light Mean when the car still starts?

  That’s often an early warning. The system is seeing intermittent faults but hasn’t fully locked you out yet. Most customers who ignore this phase eventually end up with random no‑starts or a complete no‑start.

• What is a Passlock bypass resistor?

  A resistor “bypass” is a partial fix that only tricks the system into thinking the right key is present. It still relies on the original theft‑deterrent module to send the final “OK” signal, so when that module fails, the resistor trick stops ...