Security light problem.

[bigthaiboy]

Hi,
I just bought a '94 Le Sabre Ltd. The "Security" light is constantly illuminated. The warning light was stuck on when the previous owner of the car of 7 years bought it. Any ideas of what causes this please? Did the Limited come with an alarm or immobiliser as standard?
Many thanks.

[avatar307]

Most likely the PassKey resistor (the little metal thing in the side of the ignition key) or the PassKey contacts inside the ignition cylinder are defective/worn out. Or the PassKey module could be fried, or the wire coming down the steering wheel could of been cut, etc...

The security light is illuminated because the PassKey systems has gone into Fault mode. It cannot get a reading from the security resistor, so it cannot determine if it is the wrong key or the right key. So instead of the system locking down the car and preventing you from starting the car, the car assumes you have the right key, disables the security system, and turns on the light to let you know there's a problem.

The PassKey system reads the resisotor value of the metal "chip" in the stock of the key to determine if it is the correct key. If the resistance is correct, the module allows the starter to crank the engine and allows the fuel pump relay to close the power the fuel pump. If the wrong resistance is read from the key, the module prevents the starter enable and fuel pump from recieving power.

However, as you can start your car, the PassKey module has entered Fault mode. There is a problem with the system that is preventing it from reading the resistance of the "chip" on the key stock.

1) You can check the resistance of the "chip" with a standard ohm/multi-meter. Both keys for the ignition should read the same vaule.
2) Check for cut wires from the steering wheel. I believe they are usually two small gauge orange wires.
3) Replace the ignition lock cylinder. Not going to be cheap, but I believe it's the only way to replace the contacts within the keyway that make contact with the resistor.
4) Replace the PassKey module.

[bigthaiboy]

Thank you for your reply. I have three sets of ignition keys, but the security light remains on regardless of which key I use. As I said before, according the the prevoius owner (my mother-in-law), the light has been constantly showing for at least 7 years, but has never effected any part of the car's functions. Apart from that one thing, the car drives perfectly.

I've now simply put a piece of black insulating tape over the light so it now cannot be seen. I just thought the car may have come with a factory alarm system which may have died or been disconnected.

Thanks again.
John.

[gklane]

Hey have a simular problem with my 99' Lasabre. The difference is that mine will not crank if the security light comes on. You have to wait 3 minutes, the light will go out and you can try again. Sometimes it takes 4 or 5 tries before the car will crank.

Now it does interest me that you said that the security system went into fault mode. Could I force mine to go into fault mode by cutting the correct wire? If so what wire should i cut? I would not care if the light stayed on as long as it cranked.

What do you think?

[gklane]

Well a quick update. I tried cutting the wire and the security light just blinks and the car will do nothing.

[taser1984]

Originally Posted by gklane

Hey have a simular problem with my 99' Lasabre. The difference is that mine will not crank if the security light comes on. You have to wait 3 minutes, the light will go out and you can try again. Sometimes it takes 4 or 5 tries before the car will crank.

Now it does interest me that you said that the security system went into fault mode. Could I force mine to go into fault mode by cutting the correct wire? If so what wire should i cut? I would not care if the light stayed on as long as it cranked.

What do you think?

You can force it into a fault mode this way:
When the car is running, if the module senses a fault, it will go into fault mode. The "easy" way to cause this is to start the car, then cut one of the wires that go to the key cylinder. That should work.

Now, if you want to go about it making it look a little neater, you'll want to find the module (generally behind the glove box) and while the engine is running, cut either the purple/white wire in position B7 or the white/black wire right next to it. Those wires go to the ignition cylinder.

Then, if you want the light to go out, you can cut the dark green wire in position A5. Keep in mind that the anti-theft system will not work if you do this.


___

Alternately, the common weak spot in this system is the very small wires in the steering column. They break. That's probably what needs to be replaced to get the system back to functioning normally.

[gklane]

Thanks for the post. I did finally get the problem worked out. I had a remote start installed in this car about a year ago. I thought they had installed a bypass module but it turns out they installed a resistor inline.
Evidently the resistor had a poor connection. It was reconnected and everything is now good.