passlock problem

I would try resetting the system which can be done by doing a hard reboot. Remove the negative battery cable and hold it to the positive cable for 5 minutes and this will discharge the capacitors clearing the system memory and allowing the protocol to start over.

Here is a guide that can help

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

Please let us know what you find. Run the codes as well.

Cheers

on this particular truck the resistor stuff is inside the lock cylinder for the ignition. it is passlock II . 2003 sierra. the key is a normal key. there are no OBD2 trouble codes. maybe changing the ignition lock cylinder is the fix i can't tell.

Ignition switch is more common to fail and need codes to conform suspicion

Try and do 30 Minute Learn Procedure

Turn ON the ignition, with the engine OFF. Attempt to start the engine, and then release the key to ON, vehicle will not start. Observe the SECURITY telltale, after approximately 10 minutes the telltale will turn OFF. Turn OFF ignition, and wait 5 seconds.

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 Sensor Data Code and/or Passwords on the next ignition switch transition from OFF to CRANK.

IMPORTANT: The vehicle learn the Passlock 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.

Start the engine. The vehicle has now learned the Passlock Sensor Data Code and/or password.

With a scan tool, clear any DTCs if needed. History DTCs will self clear after 100 ignition cycles.

thanks for the photos. I am wondering is the ignition switch separate from the ignition cylinder? Also, do you have a diagram relating to the procedures for removal of the components described in your reapair steps?

You have an ignition switch and ignition cylinder lock Need special tool

can i just install an ignition switch and try and see if it fixes the problem? is the special tool for removing the ignition lock cylinder? also can't you just use an allen key wrench or something to remove the ignition lock cylinder?

Most common to be the switch and not the cylinder lock
Inspect closely the wiring harness too
You can use whatever available to you and make your own special tool knowing what it look like

I finally did what you said by resetting the system on a reboot and it worked and I drove it but then it started doing it again. I think the security module is bad?

Makes sense I have seen these modules go out.

The Ignition lock cylinder and keys do not contain any coded electronic components. The lock cylinder housing contains the coded electronic components. Changing an ignition lock cylinder or adding a key is a purely mechanical process which does not affect the vehicle theft deterrent system. To add a key, simply cut a new key to match the existing one. To change the lock cylinder, simply replace the existing lock cylinder with one of the same type

i went to the dealer and they told me there is only an advisory or something that is 7yrs 70,000 miles for the module not a recall.?

took it to the dealer and when i took it in that night the light was not coming on anymore(padlock light) and they said they could not find anything wrong and it was hard starting and they tried to sell me a fuel press regulator, but i know for a fact the padlock light was coming on. will there be codes stored if the light went away? i told them keep the truck until the light comes on for them.

codes should be stored unless battery was disconnected or codes were cleared

well, the dealer said the light was not coming on so all they noticed when they read the codes for the system and determined the security module (BCM) was bad. So I had it replaced and now everything works. ($650.00) Thanks for hanging in there will me, I love this site.

Glad you could get it fixed, that kind of problem can be tough. Please use 2CarPros anytime we are here to help

Cheers