security light on all the time

**steve01** · 07-04-2015, 09:04 PM

Tried it and it didn't help. I will take another look at the circuit board under a scope but I have a bad feeling I need a new BCM. If I buy a used one I think I need the key that was with the car it came out of? I heard that a new one will learn a key resistance once and that's it.

**speedyWS6** · 07-05-2015, 01:10 AM

Steve,

Shame it never worked!

I had the same "oh damn" feeling when the solder fix never
worked on mine.

You are right in saying you need the right value resistor in your key
but from what i have read the reverse to your thinking is to determine
your present keys rating with a meter and then find a BCM which has the
correct rated resistor fitted.

Having said that i bet it is not that simple...... Never is, is it!!?

**pajeff02** · 07-05-2015, 05:56 AM

Have you continuity checked all the wires? With the BCM harness and door harness connectors unhooked, check each wire for continuity and ground to ensure that you do not have a broken wire or short in the harness somewhere.

**steve01** · 07-05-2015, 11:58 AM

SpeedyWS6 - how do you find a BCM with the correct rated resistor?

pajeff02 - I can do that but since all functions work I am not sure there is a wiring problem. Door locks work (panel switch and remote), courteous lights work, car starts, etc. Can you or anyone post good wiring diagrams?

**speedyWS6** · 07-05-2015, 11:52 PM

Steve...

Like i said, things are never simple, are they and when i thought i would need a replacement
BCM i headed to good old ebay and there are numerous people selling BCM's and stating
the value of the resistor fitted to it. such as.... 97 02 Camaro Firebird Trans Am BCM Body Control Module UPL 3 | eBay
I am the last one to claim to know, fully, what is required for a successful swap but it seems quite straightforward?!
I assume they are able to test the value of the BCM resistor somehow? I guess you have to believe them!!??

You have mentioned previously how you may need the matching key. Some are being sold with the key but even if the
resistor match is correct, how would you get the "new" key to operate the lock barrel correctly? Hmmmmm?

Here is another link to a helpful page if you have to get busy with a meter to find out your keys value.
4th Gen LT1 F-body Tech Articles

Hopefully you can sort your problem without the need for a replacement BCM?

As far as the wiring diagrams go, Jeff was a huge help here for me but coincidentally,
after i had done with the problem a bud mailed me a link to ALL the schematics you would ever need!!

http://www.mediafire.com/?40mfgeoe4ctti

I have no idea how commonplace the BCM fault is but i would hope it is something more simple!!

Good luck...

Trev

**steve01** · 07-20-2015, 09:00 PM

Hey guy
Sorry it took so long to get back to this. Heres the latest. I checked all of the wiring an was convinced the BCM was bad. I ordered a new refurbished from Rock Auto. Now the problem is different. The car sarts fine but the security light flashes and the remote door lock/alarm key FOB doesn't work. I suspect that the new BCM needs to be programmed to match my Key FOB. Does this sound correct? If yes, is there a simple procedure or do I need to go to the dealer? If its not a programming issue then I am lost or I got a bad BCM.

HELP!!!

**pajeff02** · 07-21-2015, 05:06 PM

Yes, they need to be matched. I will have to look at my books though to see how that all works.

**steve01** · 07-21-2015, 05:58 PM

I was able to program the key fob. Pretty simple but the security light still flashing. All function are working and the car starts and runs fine. I decided to put the old bcm back in now i am back to where i started. The security light is on all of the time but all functions work and car starts fine. I did notice that the driver side door will set the alarm off. I didn't realize there was a delay on the drivers door before the alarm goes off. It may have always worked. So now i have no clue what to try! Could this be an ECM problem

**pajeff02** · 07-21-2015, 06:57 PM

According to the manual, the BCM will automatically program to the resistance of the ignition key being used at the first ignition on cycle. It is a one time thing so as your car started it apparently worked correctly. The manual further states that the BCM should not be replaced unless called for by the diagnostic procedures - most faults are wiring, connector, or system component related.

**pajeff02** · 07-21-2015, 07:01 PM

The flashing security light (one flash per second) means there is a system fault. It recommends retrieving codes (I think I posted all that earlier) and then performing a series of tests that require a scan tool.

**steve01** · 07-21-2015, 08:14 PM

What does the solid security light on mean. My original BCM gives a solid light,
The new one gives the flashing light.

As for the scanner do you mean an OBII or a gm tech2 and where does the gm tech 2 plug into

Thanks

**pajeff02** · 07-22-2015, 07:18 PM

On all the time is either a short to ground in the indicator control circuit or a bad BCM.

**Mikako** · 03-13-2016, 12:38 AM

Check your wiring.
Seems there is something gone ugly wrong.

Also check the voltage set at the stepper drivers. Set them all to 0.55V.

Disconnect all motors and heaters and then connect them back one at a time to see what happens.

**9T8WS6** · 07-24-2022, 10:04 PM

I am about to undertake this project. UPDATE: For radio and windows operation.
Is disconnecting the battery necessary? Before or after?
I've watched a lot of videos on the issue but didn't notice mention of this.
Thanks.