2004 monte carlo security light on message screen

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7779jesse
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Joined: Thu Feb 27, 2014 11:16 pm

2004 monte carlo security light on message screen

Unread post by 7779jesse » Thu Feb 27, 2014 11:21 pm

I have a 2004 Chevrolet Monte Carlo. On the message screen it says service vehicle soon "security" but the car starts and runs fine never dies and never fails to start. It stays on when the car is running also. What does this security light mean? I have changed the ignition switch and key cylinder with no luck in solving the issue..Any ideas?

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carriedi
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Joined: Wed Apr 10, 2013 12:42 pm

Re: 2004 monte carlo security light on message screen

Unread post by carriedi » Fri Feb 28, 2014 1:08 am

the "security" comes on when your VTD (vehicle theft deterrent) doesn't see a signal or an incorrect signal from the passlock sensor. If it sees a wrong signal when you go to start it will not let the engine stay running. (the anti theft part) If if loses the communication while the engine is running it shows the "security" message but since it was already started with the correct signal, it allows the car to run and start like a default mode. What ever you do, DO NOT CLEAR CODES! Clearing the codes now will erase the memory that you lost the signal after you started your car and then lost passlock signal and your car will no longer start. It will have a clean memory and now see that there is no signal or a wrong signal and lock your out of starting the engine.

you will need to have your passlock sensor checked out to see if the sensor or the wiring may be damaged. A Tech2 scanner is the best tool to look at the system. Some other scanners may be able to show the system but the Tech2, I have found, is the best tool for the job.

So you can just keep driving it the way it is or have the passlock system diagnosed and fixed. It is not the ignition switch (electronic switch). It's the three wires (black-ground, white-B+ and the yellow-data) the go into the ignition lock cylinder.
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7779jesse
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Joined: Thu Feb 27, 2014 11:16 pm

Re: 2004 monte carlo security light on message screen

Unread post by 7779jesse » Fri Feb 28, 2014 9:47 pm

OK great info. I did replace the pass-lock sensor with the 3 wires with the key cylinder. do you know what the voltage or values are at each one of the 3 points in the pass locks sensor wires? I can check it with my fluke meter.

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carriedi
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Re: 2004 monte carlo security light on message screen

Unread post by carriedi » Sat Mar 01, 2014 3:40 pm

the voltage that the passlock is concerned about is the return voltage. you should have voltage, ground and return. the return is decided by your key and lock cylinder. That voltage will vary according to the vehicle. that's how the computer will see if it is the correct key or not.

If you do the relearn for the passlock you should be good, (if everything else is ok)
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