what does the BCM (Body control module) do???

[muggo05]

hey guys just wandering what the bcm actually does and what the difference is between the different level bcm's??

i'm assuming level 1 is exec etc
2 is maybe berlina and calais
3 maybe statesman and caprice??

bad guesses i know!!

anyway i have a VS S pack and wandering if there is any benefit to upgrading to a higher level BCM?

Thanks for the lesson everybody!!!

[markovr]

They arent a plug and play upgrade...low and medium have the same plugs and similar wiring ...high uses different loom and has more plugs/wiring feeding it.Your keyhead talks to the bcm when you try to start that sends a data to you ecm to get all the fuel injection and ignition going so it runs ....... so another bcm means new keyheads
BCM also controls a lot of different things that on older cars were separate modules like door locking, power windows, theft deterent wiper intermittent control etc.

[danja]

BCM controls things like power windows, central locking, air-con/climate control, alarm/immobiliser, priority keys etc (most electrics not related to the powertrain)

The only time you'd want to think about upgrading it is if you're retrofitting a feature which isn't supported by your spec of BCM. Just upgrading the BCM alone isn't going to give you anything.

AFAIK there are 4 specs of BCM, low/mid/high/luxury.

[cxcxcxvcvcvc]

hhmm, maybe my bcm is playing up! I have to press the unlock button several times on my key head before the car will turn over,it unlocks the doors first press though!

[danja]

Could just be the key head. I had one which was on the fritz, would unlock the doors usually if you were pretty close to the car, but the immobiliser would randomly kick in while starting the car. New key head and was sweet.

[OzJD]

Most, if not all of the things the higher level BCMs do can be done with simple circuits

[cxcxcxvcvcvc]

Could just be the key head. I had one which was on the fritz, would unlock the doors usually if you were pretty close to the car, but the immobiliser would randomly kick in while starting the car. New key head and was sweet.

Cheers Danja!
My key head is pretty buggered, i might get it replaced soon and see if that makes any difference

[muggo05]

so is my bcm buggered then if mine does this??

- when i unlock the car (two stage unlock) by pressing the button just once ie drivers door only, if i leave the door open for more than a couple of seconds, it will automatically unlock all the doors. however if i unlock just the drivers door and jump in really quickly, the other doors will stay locked until i open the door again.

make sense?? lol

[kopper69]

muggo05, are you sure someone hasnt fitted an aftermarket system? Has the car always done this?

cxcxcxvcvcvc, if the new key head doesnt fix it, it could be the key reader. The metal ring on the ignition barrel may just need to be bent out a little to make contact with the metal tab on the key.

[muggo05]

@ kopper69 - yeah mate its all factory, has always done it since i got the car. and if the car is unlocked, it will try and keep unlocking itself like if you keep pressing unlock on the key. REALLY ANNOYING!!

so new key head from holden and $150 out of pocket then??

***starts giving CPR to wallet***

[stocky]

you can get keyheads cheaper on ebay. send them a BCM code and they cut and code them for you. i think its less than $100

[BlackVXGTS]

Some info on BCMs (probably more than you want).

Attachment 60276

Attachment 60277

[muggo05]

thanks mate thats awesome

[NeilB]

Mr Mint do new heads. About $80 from memory for the head and key.

[muggo05]

ok cool, i'll suss them out and see what they can do