security light on why?

Hello, I'm Danny.

How about trying our sites anti-theft, security system reset. Here is the tutorial:

https://www.2carpros.com/articles/how-to-reset-a-security-system

After reading just scroll the page to find Chevrolet. Let us know what happens and we'll go from there. Hope this helps and thanks for using 2CarPros.

We tried these things... Nothing has worked ..

Hello again.

Please do a reboot

https://www.2carpros.com/articles/step-by-step-guide-performing-a-hard-system-reboot-for-your-vehicles-electronics-systems

Danny-

A couple of months ago our truck quit running we replaced the crankshaft sensor and it ran fine for a few months. now we are having the same problems and our security light is coming on. what do we need to do.

If you have a spare key try it. If not try cleaning off that key where the pellet is and try again. I would do a hard system reboot, remove the negative battery cable and hold it to the positive post for 1 minute then reconnect. This will discharge all capacitors so the system can come back online. This guide can help as well.

https://www.2carpros.com/articles/how-to-reset-a-security-system

Please run down this guide and report back.

Sometimes I try to start my truck and it will not crank, during this time the security light comes on and stays on. I have to wait a good ten to fifteen minutes before the security light goes out and the truck to start.

There is an error in the security system module.
Get it checked for trouble codes and come back if you need them translated.

Bad theft module or wrong key my friend. :)

truck wont start and sercurity lights comes on and wont go off key isnt in ignition

GM PASS LOCK RELEARN- Ignition to "run" position, try to start and let key return to "run" position
Approx ten minutes security light will go off
turn key "off" and wait 5 seconds
repeat 2 more times for a total of 3 relearns.
Turn key off, then start it

I replaced the ABS on my truck but now it doesn't start and a security light appears on the information.

Good afternoon,

It sounds like the key has forgotten the password.

I assume you removed the battery cable. this is common when the cable is removed. I posted the re learn procedure below.

Roy

PROGRAMMING REPLACEMENT PASSLOCK(TM) SENSOR, BCM, OR PCM

IMPORTANT:
^ The body control module (BCM) must be programmed with the proper RPO configurations before performing learn procedures. See Body Control Module (BCM) Programming/RPO Configuration.
^ If replacing the BCM with a GM Service Parts Operations (SPO) replacement part, the module will learn PASSLOCK(TM) sensor data code immediately. The existing PCM however, must learn the new fuel continue password when the BCM is replaced.
^ If replacing a PCM with a GM Service Parts Operations (SPO) replacement part, after programming, these modules will learn the incoming fuel continue password immediately upon receipt of a password message. Once a password message is received, and a password is learned, a learn procedure must be performed to change this password again. A PCM which has been previously installed in another vehicle will have learned the other vehicle's fuel continue password and will require a learn procedure after programming to learn the current vehicle's password.

CONDITIONS
Use this procedure after replacing:
^ Passlock(TM) Sensor
^ BCM
^ PCM

LEARN PROCEDURES
There are two available methods to perform the programming procedure:
^ A 10 minutes procedure which requires a Tech 2 and a techline terminal.
^ A 30 minutes procedure which does not require the use of any tools.

10 Minute Learn Procedure

TOOLS REQUIRED
^ Tech 2
^ Techline terminal with current Service Programming System (SPS) software

1. Connect the Tech 2 to the vehicle.
2. Select "Request Information" under "Service Programming".
3. Disconnect the Tech 2 from the vehicle and connect it to a techline terminal.
4. On the techline terminal, select "Theft Module Re-Learn" under "Service Programming".
5. Disconnect the Tech 2 from the techline terminal and connect it to the vehicle.
6. Turn ON the ignition, with the engine OFF.
7. Select "VTD Re-Learn" under "Service Programming".
8. Attempt to start the engine, then release the key to ON, vehicle will not start.
9. Observe the SECURITY telltale, after approximately 10 minutes the telltale will turn OFF, the vehicle is now ready to relearn the PASSLOCK(TM) Sensor Data Code and/or password on the next ignition switch transition from OFF to CRANK.
10. Turn OFF the ignition, and wait 5 seconds.
11. Start the engine, the vehicle has now learned the password.
12. With the Tech 2 scan tool, clear any DTCs.

30 Minute Learn Procedure
1. Turn ON the ignition, with the engine OFF.
2. Attempt to start the engine, then release the key to ON, vehicle will not start.
3. Observe the SECURITY telltale, after approximately 10 minutes the telltale will turn OFF.
4. Turn OFF the ignition, and wait 5 seconds.
5. Repeat steps 1 through 4 two more times for a total of 3 cycles/30 minutes, the vehicle is now ready to relearn the PASSLOCK(TM) Sensor Data Code and/or passwords on the next ignition switch transition from OFF to CRANK.

IMPORTANT: The vehicle learns the PASSLOCK(TM) Sensor Data Code and/or password on the next ignition switch transition from OFF to CRANK. You must turn the ignition OFF before attempting to start the vehicle.

6. Start the engine. The vehicle has now learned the PASSLOCK(TM) Sensor Data Code and/or password.
7. With a scan tool, clear any DTCs if needed. History DTCs will self clear after 100 ignition cycles.

i had a wire burn out which controlled my low beams. the wire was burnt and disconnected from the terminal. this is right behind my steering wheel. i took the white block off which the terminals where placed in replaced the severed terminals placed them back in th block and put the block back on to the copper prongs. i put my key in the ignition and a security light appeared in my message box. my truck will not start and i dont know what to do can you help me?

I do not understand what you are saying "it will stay cranked"? Does it start, run then shut off? The security will shut down the fuel pump. Try this to see if it will relearn the key:



1- Turn key to 'run" position, try to start and let key return to "on" position.
2-After approximately ten minutes the security light should turn off.
3-Turn ignition to "off" position and wait five seconds.
4-Repeat steps 1-4 two more times for a total of three cycles equaling thirty minutes.
5- Start engine.

Steps worked!

The security light comes on occasionally and stays on. Also, the truck will not start occasionally. It turns over like it wants to start but does not. I eventually get it started. The fuel pump has been replaced twice now. What could be wrong with it?

These trucks had problem with the BCM which is the car alarm. Here is the location so you can replace it, but you will need to have it programmed to the truck before it will run. The cost is about $130.00.

On the lower left side of the I/P below the steering column.

Check out the diagrams (below). Please let us know what happens.

Cheers

Nice! I did what you said and then had my truck towed free from AAA to the shop and now all fixed! I love this site :) Cost me $80.00 but I know the guy.

Security Light Stays on & Headlights will not work.

Have you done a relearn on the pass-key?
Gm pass lock relearn- Ignition to "run" position, try to start and let key return to "run" position.
Approximately ten minutes security light will go off .
Turn key "off" and wait five seconds.
Repeat two more times for a total of three relearns.
Turn key off, then start it.

I followed your instructions but I still have the same problem.
The security lights stays on all the time and the headlights will not work. Dome light and cab light will not work. If I disconnect the battery for a time and when it is reconnect the the light work until the security light comes back on.

You will need to scan it for codes, must be a stored code for the security system. Other thing you might check is all fuses and connectors. Associated with ignition and security.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

https://youtu.be/YV3TRZwer8k

Trucks been running good. Battery is less than a year old and alternator is little over a year. Shut the truck off and we started it back up the battery light was on, the security light was on, gauges quit working. Alternator is charging at 14.4v. truck cranks and runs good even with these issues.

This sounds like the cluster is the issue. However, we should start with checking for codes.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Once we know if there are codes or not we can jump into the cluster issue.

Basically the way this works is these systems all run through or are displayed through the cluster. The fact that the security light is on but the vehicle still starts, or the battery light is on and the alternator appears to be working shows that the actual systems are not the issue. It is most likely the cluster itself.

Let us know and we can go from there. Thanks

Did an engine swap from the 4.8 to a LS1 350 out of a C5. After putting the motor in went to turn it over the security came on. Did the relearn didn’t work. Changed out the ignition switch and cylinder. Did the relearn still the same thing motor will turn over but not getting spark. Where do I got from here?

So if you changed the engine you would have changed the ECM over from the other engine as well, correct? If you did this then the keys that you are using is still for the other engine control module.

I suspect the only way we are going to fix this is getting generic PCM with the theft system deleted off of it so that when it gets the ignition switch feed that it is not looking for a specific signal and it just starts the engine.

This is pretty common when we do an engine swap and these services are pretty common. In fact, I suspect you can find one where you just send you PCM off and they will remove the theft system and send it back.

If you take a look at the information below you will see how the system works.

Let us know if you have questions. Thanks

So recently I unplugged the computer in the truck listed above k1500 and left it unplugged for a few days. When plugging it back in the security became engaged and the security light is steady on not flashing... Unable to fix that I wanted to check the obd codes... The tool says no communication with vehicle... Have done some research and discovered the check engine light does not come on at all. The check gauges light comes on for a few seconds but not he check engine light. Where should I start with figuring out why the check engine light isn't functioning and does this immediately mean the PCM is bad? The truck has been running or weeks and haven't ever noticed the check engine light coming on.

Hi,

Did you have the battery disconnected when you unplugged the PCM? Also, if you leave the key in the on position for approximately 10 minutes, does the security light turn off?

Check pin 16 in the DLC to see if there is power present. See the attached pics.

Let me know what you find.

Joe

Okay, will do. First thing in the morning. Honestly can't remember if the battery was unhooked or not. Have tried several relearn procedures with the key.. light does not go off.. doesn't even blink.

The obd tool isn't self powered however and does power on so i assumed there wasn't a problem at the obd plugging for power....

Hi,

I should have asked this earlier, but can you confirm the engine size? The 4.8L doesn't exist on this vehicle. If you look at the attached picture, it shows what I am seeing. I need to confirm the correct engine to really dig into the wiring schematics. Pin 16 is a standard power supply. That's why I was able to get this far.

Also, if you disconnected the PCM without having the battery disconnected (disconnected or reconnected), it could have caused damage to the PCM.

Let me know.

Joe