1999 Blazer Security Light flashes without key in ignition
 

I have a 1999 Blazer. Why does my security light keep flashing every time the door is open even without the key in the ignition? I have a 98 and an 04 Blazer and do not have this problem. In these two vehicles the security light only comes on for three seconds when the key is turned to the on/run position then shuts off. With the 99 Blazer the security light stays flashing when the door is open even without the key. This is really a nuisance because sometimes when I park or go camping or whatever I like to keep the door open, but this red light keeps flashing in my face for absolutely no reason.

Anyone?

If no one else takes this today, I’ll look at it tonight.


George

Thanks. The security light flashes without the key in the ignition when I open any of the four doors, but not the tailgate. My next step is to disable the passlock system by putting a 2200 ohm resistor in the ignition cylinder wires (cut the yellow wire, add resistor and connect it to the orange/black wire). Should get the resistor Saturday. I have no idea what else could be the problem.

This comment it based on memory.

When I was trying to track down why my electronic door lock would not work, I found myself tracing lots of wires. Turns out that as part of my tracing the wires, I had taken the door panel off and the lower part of the instrument panel off below the steering wheel. I then got weird errors including, if I remember correctly, the security light was on and the dome light would not go off. I went so far in trying to track down these issues that I traced what I thought was a possible problem back to my lift-gate lock mechanism.

The upshot was that the extra errors I got were because with the door panel off, the door-closed switch was not being depressed and that I had disconnected a very small module that lives on the inside of that lower panel I had removed below the steering wheel. It was this little module that was causing my security light to stay on.

So, you might check if there is anything disconnected on the panel under the steering wheel.

Does the vehicle start and run normally? Why are you going to hack the passlock resistor?

George

I did not see before that Christine had posted before me. The reason I asked about the passlock system is because the security light indicates status and faults form two different systems, the vehicle theft deterrent and the content theft deterrent systems. The VTD system uses the passlock resistor, disables the vehicle during a fault and only controls the security light with the ignition on. The CTD system only controls the security light with the ignition off and involves the doors and keyless entry. If the truck starts and runs normally then the passlock resistor is not involved.


George

Yes, the vehicle starts and runs normally, but does seem like there is a small drain on the battery, but I am not sure yet. It seems like the headlights are dim at night, but this is probably a different problem - no sure. Either way I would like to bypass/disable the passlock because I do not want to see this red light flashing in my face every time I open the door without key in ignition when there is no problem. Quire frankly, I do not want to see this security light go on ever again - even if there is a problem! Plus disabling it will avoid any problems that might occur with it in the future, and their are tons of horror stories about "no start" issues with it online, shutting off the fuel pump, etc. I live in a safe area, this is nearly a 25 year old vehicle, and at this stage of it's life, I am not concerned at all about any possible theft or entry.

So is there also some way to disable the CTD (content theft deterrent)? As I said, I really want to just disable this whole system so as not to ever see the security light ever again. The simpler the better.

If you want to bypass the passlock sensor to prevent a future failure of the passlock system that’s fine but it will likely not help you with this problem. Just make sure that you solder and insulate your work so that you don’t introduce a new problem.

So this only occurs with the truck off and any door gets opened except the rear hatch? Do you use the keyless entry system?


George