Ignition key reprogram?

Tiny
RACHELLYNN1996
  • MEMBER
  • 2001 BUICK CENTURY
  • V6
  • 2WD
  • AUTOMATIC
  • 95,000 MILES
Hello, I lost the keys to my car listed above and couldn't afford to get a new key cut from the dealer. I bought a new ignition tumbler and set of keys and replaced the part myself, but the engine is prevented from turning over because of a security issue. I bought some electrical resistors for the GM cars, a set of 12, but I don't know where or how to install them. I just need some help or information about how to install them without spending any more money if possible. Thanks.
Tuesday, September 22nd, 2020 AT 12:41 PM

3 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Take a look at the attached info. We have no way of telling you how many resistors your BCM is looking for. This is the "secret" info that prevents people from stealing cars. Plus the resistor is in the key and each is a different size. So it is not a series of resistors but instead just one of 15 different sizes that the BCM is looking for. Then when the metal key matches the lock cylinder in the ignition it allows the vehicle to start.

Does this make sense? Basically I am saying that we need to have the key match the BCM in order for it to work.
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Tuesday, September 22nd, 2020 AT 5:40 PM
Tiny
RACHELLYNN1996
  • MEMBER
  • 1 POST
Hi, I understand this. I just need to know how to install the resistors I bought or how to somehow remove the BCM?
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Saturday, September 26th, 2020 AT 2:19 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
So if you are going to install these resistors, you have to measure the resistance of the key so you know the amount of resistance the BCM is looking for.

Then you don't need to put them in the BCM, you can put them anywhere in line between the ignition key cylinder and the BCM.

Take a look at the wiring diagram and you will see two wires going to and from the resistor pellet.

You need to put the resistors in the reference wire (purple/white) wire so that the 5 volt signal is decreased to the proper voltage that the BCM is looking for. This will eliminate the need for the key to have the proper resistance.

So start with measuring the resistance of the key and then find a resistor or a combination of resistors to match that resistance. Then just cut the wire and solder in the resistor in the wire.

Most people will install this by the ignition switch because that is the easiest place to access. Does that make sense? If you just prefer to put it by the BCM, that is fine as well. I attached the process from the manual.
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Sunday, September 27th, 2020 AT 9:09 AM

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