Computer Diagnostics and Tuning Technical discussion on diagnostics and programming of the F-body computers

Help with the BCM!!

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Old 12-13-2007, 06:16 PM
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Exclamation Help with the BCM!!

I hope I can put this thread here and get some help.

the Body Control Module (BCM) in my '96 Z28 is malfunctioning. It is causing:
- The remote keyfob does not operate the central lock (I can open and lock the door only with the manual sliding lock or the door key).
-The courtesy lights which were working OK, now don't work and the fuse blows (replaced it twice already). The bulbs are the correct type and the 20amp fuse is correct too.
-the new door lock buttons do not operate the solenoids (they worked fine for a few days before the BCM started acting up).
-it causes a clicking noise every 10 seconds under the glovebox which I'm afraid is draining my battery.

The keyfob still arms and disarms the alarm and flashes the turn signals and honks the horn when doing so. the 3rd. button still unlocks the hatch. My car has not been tampered with, has no aftermarket electronics, even the radio is the original delco-Bose one.

I have spent HOURS researching the web and I'm only more confused now about the BCM. No auto parts store (napa, autozone, pep boys, advance, etc) carries a BCM for my Camaro, there are used ones on EBay, but I can only get it new from gmpartsdirect.com and it costs $138 + shipping...

After reading everything in websites and forums including conflicting information and dissassembling some pieces in my car, I found my OEM BCM part is 16243951 (stamped "made in Singapore" damn!). It seems like:

-the 93-95 uses one type of BCM (behind the passenger side kick panel), the 96-97 uses another type (under the glovebox like mine) and the 98-2002 yet another one, and even within years there is a variance between the cars with anti-theft and the ones without (I thought all Camaros were sold with a remote keyfob?)

- I can't buy a used BCM, because the BCM chip programs itself with the Pass-key code the first time the ignition is turned to run. I would have to get one with the same ID as mine, which I don't know which one is so anyway I have to shell out the $138 + shipping. So I resigned myself to having to buy it new before my actual one gets worse and disables the ignition or something.

-I called a big place that refurbishes ECU computers here in FL, but they don't mess around with BCMs. they said: "There is programming involved in the car so we don't do it, its complicated go to a Chevy dealership"

Now, If I get a new BCM, it seems it's not just a matter of disconnecting the battery, replace it and reconnecting the battery again, because "some sort" of programming has to be done between the ECU and the BCM. I worked at a Chevy dealership some time ago and believe me I don't want to get ripped off, or have novice technicians making things worse and telling me I have to unnecesarily buy X, Y and Z new parts (usually out of stock and expensive). Does anyone know what "programming" is involved? with what equipment? an OBDII scanner? or just removing the radio fuse and punching some buttons in sequence like programming a keyfob?

Any ideas? why is this part so hard to get? would seem that it is bulletproof if that is so... or am I of the few ones that has had trouble with a BCM?
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Old 12-14-2007, 08:47 PM
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BCMs are pretty bullit proof, with the exception of F-bodies.
in the Generals infinate wisdom there are relays built in to the bcm that
are in the electrical center and easily replaced on other cars.
new pcms and bcms are shipped blank and programed to the car.
there are alot of people that can program a pcm including some auto parts
stores. very,very few people outside the dealer can program a bcm.
a salvage yard bcm will work if you turn off vats in the pcm.
heres a link to a programer that may or may not still be for sale, there are pics in the third thread but i can not post them.
http://www.monodax.com/forums/buy-se...cable-set.html
another option is to wire around the bcm and creating your own relay panel.
or bite the bullit and go to the dealer.
the interior light fuse could likely be another problem.
if you have not done so already check the connections at the bcm. it is quite common for green **** growing inside the connectors and bcm.
$138 sounds good if its already programed.
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Old 12-14-2007, 08:56 PM
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I've got a spare BCM sitting under my desk. My foot is on it right now.

I bought it for my 96 TA used for a mysterious BRAKE light that came on for no reason one sunny summer day. I realized for some reason the BCM suddenly realized my Traction controll unit was not connected for the past 3 months and set a code. I hooked up the traction control unit and all is well.

Long story short, the BCM's been sitting here ever since if you want it for what I paid which I dont remember what that was.

Last edited by dookie454; 12-15-2007 at 01:13 AM.
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Old 12-15-2007, 12:40 AM
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Originally Posted by dookie454
I've got a spare BCM sitting under my desk. My foot is on it right now.

I bought it for my 96 TA used for a mysterious BRAKE light that came on for no reason one sunny summer day. I realized for some reason the BCM suddenly realized my Traction controll unit was not disconnected for the past 3 months and set a code. I hooked up the traction control unit and all is well.

Long story short, the BCM's been sitting here ever since if you want it for what I paid which I dont remember what that was.
This should be your answer........ if it is the right BCM the resistor value isn't that important as you can take you existing key in to a locksmith and have it re-cut with a resistor pellet value that matches the replacement BCM's and it could matter less what te original value is.
Tal
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Old 12-15-2007, 01:14 AM
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sorry i meant BCM realized the traction control was not connected (instead of not disconnected...)

Last edited by dookie454; 12-15-2007 at 01:52 AM.
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Old 12-15-2007, 01:52 AM
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Sorry, quoted the wrong person,, I was trying to tell the OP that your unit would work if the #'s match but the pellet need not match, a locksmith can cut him a new valued key.
Tal
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Old 12-15-2007, 09:15 AM
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i work for gm and i would have to look up how to program a bcm for car because different year modules program differently. what year is your car? on older cars like f bodies all you should need would be a tech 2 scanner. i put one on yesterday in a 02 malibu and all you have to do to set those up is use the scanner and the preform the theft relearn for passlock to work. if you get me the year i could look it up in a service manual to make sure i am giving you the correct info.
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Old 12-16-2007, 03:40 PM
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93-95s don't have BCMs at all.

A brand new BCM for a 1996 automatically programs itself to the key upon the first key ON sequence. The security light should stay on for about 5 seconds and then go out, indicating the BCM is properly programmed.
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Old 12-16-2007, 08:26 PM
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Originally Posted by shoebox
93-95s don't have BCMs at all.

A brand new BCM for a 1996 automatically programs itself to the key upon the first key ON sequence. The security light should stay on for about 5 seconds and then go out, indicating the BCM is properly programmed.
That is great news Shoebox!!! so basically I can just get a new piece and replace it myself! well, I'll see if I can find it somewhere else, because GMpartsdirect seem to have a lot of conditions and terms for everything from payment, shipping time to core return (a no-win situation for the customer). If not guess I'll have to order it there.

By the way, I replaced my starter 2 days ago and the battery today. Will the clicking BCM drain the new battery? I ask because I don't know how long it will take to get it from GM parts direct.
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Old 07-30-2008, 04:30 PM
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Originally Posted by Interceptor1
the Body Control Module (BCM) in my '96 Z28 is malfunctioning. It is causing:
- The remote keyfob does not operate the central lock (I can open and lock the door only with the manual sliding lock or the door key).
-The courtesy lights which were working OK, now don't work and the fuse blows (replaced it twice already). The bulbs are the correct type and the 20amp fuse is correct too.
-the new door lock buttons do not operate the solenoids (they worked fine for a few days before the BCM started acting up).
-it causes a clicking noise every 10 seconds under the glovebox which I'm afraid is draining my battery.

The keyfob still arms and disarms the alarm and flashes the turn signals and honks the horn when doing so. the 3rd. button still unlocks the hatch. My car has not been tampered with, has no aftermarket electronics, even the radio is the original delco-Bose one.
I know this is an old thread, but was this problem ever solved?
My car has these exact syptoms. After plenty of research I was pretty confident that a new BCM would cure it so I bought a brand new one from a local dealership.....installed it and programmed it like shoebox said to....and it's still doing the same thing

Any ideas?
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Old 07-31-2008, 07:51 AM
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I'm gonna go ahead and post up this info for anyone that may do a search in the future...

If you're having these symptoms, check your "courtesy" fuse. My fuse was good, I tested it with one of those cheap fuse testers, so I kept on overlooking it. But after checking it with a real test light I realized that it was not making contact in the fuse box. I bent the terminals in the fuse block back into shape, now the fuse makes contact and everything is back to normal.

Last edited by Colin91Z; 07-31-2008 at 07:55 AM.
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