BCM replacement security light doesn't show up
Thread Starter
Advanced
Joined: Nov 2014
Posts: 69
Likes: 3
BCM replacement security light doesn't show up
Hi everyone!
I just replaced the BCM on my 2002 Z06.
When i plugged the battery wires on, i saw the security light flashing then it went off and didn't show up anymore.
No matter what I'm doing, it doesn't show up and the car doesn't crank.
PCM shows P1631H C code which is normal cause the BCM hasn't been paired with the car but I don't understand why does the security light stay off.
Any idea ?
I just replaced the BCM on my 2002 Z06.
When i plugged the battery wires on, i saw the security light flashing then it went off and didn't show up anymore.
No matter what I'm doing, it doesn't show up and the car doesn't crank.
PCM shows P1631H C code which is normal cause the BCM hasn't been paired with the car but I don't understand why does the security light stay off.
Any idea ?
Last edited by seb.a; Nov 19, 2025 at 12:38 PM.
Melting Slicks
Joined: Sep 2021
Posts: 2,555
Likes: 1,213
Hi everyone!
I just replaced the BCM on my 2003 Z06.
When i plugged the battery wires on, i saw the security light flashing then it went off and didn't show up anymore.
No matter what I'm doing, it doesn't show up and the car doesn't crank.
PCM shows P1631H C code which is normal cause the BCM hasn't been paired with the car but I don't understand why does the security light stay off.
Any idea ?
I just replaced the BCM on my 2003 Z06.
When i plugged the battery wires on, i saw the security light flashing then it went off and didn't show up anymore.
No matter what I'm doing, it doesn't show up and the car doesn't crank.
PCM shows P1631H C code which is normal cause the BCM hasn't been paired with the car but I don't understand why does the security light stay off.
Any idea ?
I can post screenshots from a 2000 FSM but the process might be different for your car.
Last edited by Dads2kconvertible; Nov 19, 2025 at 09:23 AM.
Tech Contributor
Joined: Jan 2007
Posts: 19,470
Likes: 1,171
From: Dyer, IN
Hi everyone!
I just replaced the BCM on my 2003 Z06.
When i plugged the battery wires on, i saw the security light flashing then it went off and didn't show up anymore.
No matter what I'm doing, it doesn't show up and the car doesn't crank.
PCM shows P1631H C code which is normal cause the BCM hasn't been paired with the car but I don't understand why does the security light stay off.
Any idea ?
I just replaced the BCM on my 2003 Z06.
When i plugged the battery wires on, i saw the security light flashing then it went off and didn't show up anymore.
No matter what I'm doing, it doesn't show up and the car doesn't crank.
PCM shows P1631H C code which is normal cause the BCM hasn't been paired with the car but I don't understand why does the security light stay off.
Any idea ?
Thread Starter
Advanced
Joined: Nov 2014
Posts: 69
Likes: 3
Hi guys !
Thanks for answering. I wanted to perform the BCM programming but it's based on the security light that didn't show up.
There was a default code B2721 as well so i ended up thinking it was the light bulb that broke down. I took the instrument cluster off and checked the bulbs were good, set it back, tried to turn the keys on and the security light went on flashing first then steady.
I performed the BCM programming and it worked.
My question was about that security light not working. It was impossible to set the key on, wait for security light to shut off then set key off for 30sec... Without security light. Sure i know a non associated BVM explains things not working but when the only thing which is supposed to work doesn't, it becomes harder to use it...
Anyway, the engine is running now and the security light goes on for a few seconds then off when turning the ignition switch on so my problem is solved.
Thanks
Thanks for answering. I wanted to perform the BCM programming but it's based on the security light that didn't show up.
There was a default code B2721 as well so i ended up thinking it was the light bulb that broke down. I took the instrument cluster off and checked the bulbs were good, set it back, tried to turn the keys on and the security light went on flashing first then steady.
I performed the BCM programming and it worked.
My question was about that security light not working. It was impossible to set the key on, wait for security light to shut off then set key off for 30sec... Without security light. Sure i know a non associated BVM explains things not working but when the only thing which is supposed to work doesn't, it becomes harder to use it...
Anyway, the engine is running now and the security light goes on for a few seconds then off when turning the ignition switch on so my problem is solved.
Thanks
Tech Contributor
Joined: Jan 2007
Posts: 19,470
Likes: 1,171
From: Dyer, IN
Hi guys !
Thanks for answering. I wanted to perform the BCM programming but it's based on the security light that didn't show up.
There was a default code B2721 as well so i ended up thinking it was the light bulb that broke down. I took the instrument cluster off and checked the bulbs were good, set it back, tried to turn the keys on and the security light went on flashing first then steady.
I performed the BCM programming and it worked.
My question was about that security light not working. It was impossible to set the key on, wait for security light to shut off then set key off for 30sec... Without security light. Sure i know a non associated BVM explains things not working but when the only thing which is supposed to work doesn't, it becomes harder to use it...
Anyway, the engine is running now and the security light goes on for a few seconds then off when turning the ignition switch on so my problem is solved.
Thanks
Thanks for answering. I wanted to perform the BCM programming but it's based on the security light that didn't show up.
There was a default code B2721 as well so i ended up thinking it was the light bulb that broke down. I took the instrument cluster off and checked the bulbs were good, set it back, tried to turn the keys on and the security light went on flashing first then steady.
I performed the BCM programming and it worked.
My question was about that security light not working. It was impossible to set the key on, wait for security light to shut off then set key off for 30sec... Without security light. Sure i know a non associated BVM explains things not working but when the only thing which is supposed to work doesn't, it becomes harder to use it...
Anyway, the engine is running now and the security light goes on for a few seconds then off when turning the ignition switch on so my problem is solved.
Thanks
Thread Starter
Advanced
Joined: Nov 2014
Posts: 69
Likes: 3
The security light is illuminated via class2 from the BCM. All you had to do was turn the ignition to ON, and the IPC illiuminates all indicators during self test.....this would have told you the bulb was still good. It would be a remarkable concidence that you had some sort of high resistance connection to the security light bulb only.....which somehow was resolved by taking it out and putting back in.
The 12V DC is incredibly good for remarkable coincidences...
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