C5 BCM Programming or flashing
Thread Starter
Intermediate
Joined: Aug 2020
Posts: 42
Likes: 6
From: Granbury, Texas
C5 BCM Programming or flashing
Hello again friends. Looks like I will be replacing my 2000 Convertible's BCM with a reman unit. Can you guys enlighten me on what the reprogramming process actually is and who can do it? I understand you need a Tech2 or similar device and proper software. Do most auto electric shops have this equipment and software, or just dealers? Average cost? When I hear talk about flashing or re-flashing the BCM, what is that exactly? How is that different from reprogramming a reman unit? Thanks to all! Appreciate the support here.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,500
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From: Cape Coral, Florida
Hello again friends. Looks like I will be replacing my 2000 Convertible's BCM with a reman unit. Can you guys enlighten me on what the reprogramming process actually is and who can do it? I understand you need a Tech2 or similar device and proper software. Do most auto electric shops have this equipment and software, or just dealers? Average cost? When I hear talk about flashing or re-flashing the BCM, what is that exactly? How is that different from reprogramming a reman unit? Thanks to all! Appreciate the support here.
Burning Brakes
Joined: Jul 2011
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From: Southern Norway , Europe
Thread Starter
Intermediate
Joined: Aug 2020
Posts: 42
Likes: 6
From: Granbury, Texas
Friends. I appreciate the replies and forgive me for being so uninformed on this subject. Considering the last couple of comments, can I send my BCM replacement off to a shop that will program it for me? And then can I install it and have my car function normally (like start!)? Or does it have to be in the car when it is being programmed? Thanks again everyone.
Melting Slicks
Joined: Sep 2008
Posts: 3,132
Likes: 799
From: Espanola New Mexico
I may be wrong, but I believe that it has to be installed in the car, because the BCM has to be able to communicate with the PCM during the programing. The BCM programing also includes knowing what resistance your key pellet is, so even if you can send it out to be programed, you have to measure the pellet on your key, so they can enter that during programing.
Thread Starter
Intermediate
Joined: Aug 2020
Posts: 42
Likes: 6
From: Granbury, Texas
Thanks MM. You are right I am sure. Also the brake pedal sensor has to be set I believe. As far as the key resistance, I actually for once know something about my car. The vats key is a #10 with 3740 ohms of resistance. And of course the BCM needs to read that too. I was just wondering if GM had all this info already stored in their files referenced by the VIN. Doesn't look like I am going to be able to avoid a tow truck ride. Crap! I wish there was someone locally that did this programming as a mobile mechanic.
Melting Slicks
Joined: Sep 2008
Posts: 3,132
Likes: 799
From: Espanola New Mexico
As I mentioned earlier, I may be wrong about having to have the BCM installed in the car, I believe they can program the BCM to accept the key resistance the first time you start your car. I would research BCM programing before having to tow your vehicle to a shop, hopefully somebody here on the forum will chime in on this post, and yes they can flash your BCM using the cars VIN.
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Melting Slicks
Joined: Sep 2008
Posts: 3,132
Likes: 799
From: Espanola New Mexico
Read up some old posts on this forum by one of the resident experts, there is a relearn procedure for getting the new BCM to communicate with the PCM. There is a second relearn procedure for getting the BCM to accept your present key, they are both on this site if you do a search. You will need somebody with a Tech II to program/reflash your cars options configuration, but hopefully you can drive your car to a shop.
Race Director
Joined: Apr 2007
Posts: 11,150
Likes: 890
From: South Western Ontario
You definitely do not program the key resistance into the BCM. It's a relearn procedure. You can do it without the TechII.
You certainly could get someone with a bench setup to program the options if you gave them the options to set and then do the VATS relearn yourself.
You can also do the VATS relearn yourself and then drive it to the shop to get the RPO codes set.
You certainly could get someone with a bench setup to program the options if you gave them the options to set and then do the VATS relearn yourself.
You can also do the VATS relearn yourself and then drive it to the shop to get the RPO codes set.
Last edited by lionelhutz; Aug 10, 2020 at 08:51 PM.
Thread Starter
Intermediate
Joined: Aug 2020
Posts: 42
Likes: 6
From: Granbury, Texas
Lionel. Appreciate your input. Looks like if I buy a good used BCM I can have it "reflashed" and then install it. Then go through the re-learn procedures so that it will recognize the key and start/run. Then I can set up an appointment to get it properly programmed with the RPO codes. Sound about right to you?
Melting Slicks
Joined: Sep 2008
Posts: 3,132
Likes: 799
From: Espanola New Mexico
You have to do a relearn procedure for the BCM to PCM handshake, then do the relearn procedure to recognize the key, to allow you to drive it to a shop to have it reflashed. The relearn procedure for the BCM to recognize the key requires a few cycles of turning the car off and on and the on periods are minutes long, many who have done the relearn procedure recommend connecting a battery charger during the key relearn.
Race Director
Joined: Apr 2007
Posts: 11,150
Likes: 890
From: South Western Ontario
The shop will set the BCM to match the RPO options, not reflash it.
Melting Slicks
Joined: Sep 2008
Posts: 3,132
Likes: 799
From: Espanola New Mexico
I was unaware that there was only one relearn procedure, my advise on connecting a battery charger while performing the relearn is based on the fact that the key will be turned to the On position for slightly over 0ne half hour and you do not want battery voltage to drop to low during the relearn procedure. Good Luck, hope you get your C5 running again.
