BCM/Ignition Key
Thread Starter
Cruising
Joined: Aug 2013
Posts: 11
Likes: 0
BCM/Ignition Key
Hello all,
I've been doing a lot of electrical work on my 95 and just replaced the BCM. I was able to find a good used one.
Now, the key is not recognized. I realize the gizmo in the key is not being recognized by the security system anymore.
How do reprogram? From what I've gathered there are 15 different values and I may have to try one at a time until I hit the jackpot?
Thank you
I've been doing a lot of electrical work on my 95 and just replaced the BCM. I was able to find a good used one.
Now, the key is not recognized. I realize the gizmo in the key is not being recognized by the security system anymore.
How do reprogram? From what I've gathered there are 15 different values and I may have to try one at a time until I hit the jackpot?
Thank you
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
You can't, the required resistance is locked into the BCM and can't be altered.
Correct
Either get a variable potentiometer and set it each of the key ohm resistance values
See
http://www.thirdgen.org/vats_passkey_system
and connect it to the VATS wiring under the column and try to start the car ( have to wait 4 minutes between each test )
or get a locksmith to use a key interrogator to find the correct value key you need
Either get a variable potentiometer and set it each of the key ohm resistance values
See
http://www.thirdgen.org/vats_passkey_system
and connect it to the VATS wiring under the column and try to start the car ( have to wait 4 minutes between each test )
or get a locksmith to use a key interrogator to find the correct value key you need
Race Director
Joined: May 2006
Posts: 10,691
Likes: 71
From: Phoenix Arizona
You can't, the required resistance is locked into the BCM and can't be altered.
Correct
Either get a variable potentiometer and set it each of the key ohm resistance values
See
http://www.thirdgen.org/vats_passkey_system
and connect it to the VATS wiring under the column and try to start the car ( have to wait 4 minutes between each test )
or get a locksmith to use a key interrogator to find the correct value key you need
Correct
Either get a variable potentiometer and set it each of the key ohm resistance values
See
http://www.thirdgen.org/vats_passkey_system
and connect it to the VATS wiring under the column and try to start the car ( have to wait 4 minutes between each test )
or get a locksmith to use a key interrogator to find the correct value key you need
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
I have heard that the later cars have a "learn" procedure that will read the key resistor and remember it.
I don't know if this applies to your car, but here is some info related to this:
http://my.cardone.com/techdocs/pt%2077-0011.pdf
I don't know if this applies to your car, but here is some info related to this:
http://my.cardone.com/techdocs/pt%2077-0011.pdf
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
As I already stated the value is locked in on a used unit
http://forums.corvetteforum.com/c4-t...ce-values.html
http://forums.corvetteforum.com/c4-t...o-new-ccm.html
Last edited by vetteoz; Dec 4, 2013 at 06:02 AM.
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Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
Only on a new out of the box CCM when it is 1st installed
As I already stated the value is locked in on a used unit
http://forums.corvetteforum.com/c4-t...ce-values.html
http://forums.corvetteforum.com/c4-t...o-new-ccm.html
As I already stated the value is locked in on a used unit
http://forums.corvetteforum.com/c4-t...ce-values.html
http://forums.corvetteforum.com/c4-t...o-new-ccm.html
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
I saw a post somewhere from a guy who said there is an ADC (Analog to Digital Converter) in the CCM, ECM, PCM, whatever, that reads the key resistor and then converts that into a digital number that is then stored in non-volatile RAM. I thought he said you could reprogram the key resistor value using the method he spelled out,
Safety Car
Joined: Aug 2013
Posts: 4,427
Likes: 604
From: Minneapolis Mn
Vats
If you take your key to a GM dealer, they can read the value off the key. Once you have that you can either create your own bypass resister string or get a plug-in module from places like Ecklers that plug into the harness and the car reads that instead of the key. The upside is you don't need a resistor key only a key with the right teeth on it. The downside is the same so any key with the right teeth config can start the car. If you purchase the adapter I mentioned, you just unplug the wire from the ignition and plug this in so you don't cut any wiring in the process.
Team Owner
Joined: Sep 2003
Posts: 25,383
Likes: 2,736
If you take your key to a GM dealer, they can read the value off the key. Once you have that you can either create your own bypass resister string or get a plug-in module from places like Ecklers that plug into the harness and the car reads that instead of the key. The upside is you don't need a resistor key only a key with the right teeth on it. The downside is the same so any key with the right teeth config can start the car. If you purchase the adapter I mentioned, you just unplug the wire from the ignition and plug this in so you don't cut any wiring in the process.
OP - I would approach a lock service about maybe renting his Interrogator for a couple of hours and then it's "your time" and not "his time" It seems you understand so a conversation with a shop might actually work for you. I have one also but I'm certainly not close.
Do you have any sort of relationship with a "parts guy" in a dealership? If he/she understood what your needs are they might also be willing to help you. It would require a "relationship" but it's not unheard of! You need 2 hours!
Your other situation is maybe nothing you're concerned with but down the road it could be an issue. The BCM/CCM you bought has the VIN & mileage from the car that it was removed from recorded and there's no way for you to "undo" that inexpensively. Is your intention to use it "short-term" and have yours repaired? What is the reason for the swap?
Last edited by WVZR-1; Dec 5, 2013 at 03:02 PM.
