BCM starting to do my head in...

[benk]

Ok, I don't know if anyone has had a lot to do with A VR BCM but any help will be apreciated as I have run out of idea's
I'll start from the begining....
A couple of weeks ago I noticed that everytime I wanted to start the car had to lock and unlock with the keypad befor it would start everytime you turned the car off. (Never had that Issue before, could leave the car unlocked and just jump in and start it)That was ok untill the key pad stopped working, then couldn't start it at all!!!! Thought Ok the key pad has died so towed it down to holden to get a new keypad programed to it.... They tried to program a new key pad but said they couldn't comunicate with the BCM so it will need to be replaced. I said no worries I'll just locate another second hand BCM with a matched keypad. Finaly found another BCM and put it in and still no go. Holden were no help at all telling me that I had got the wrong BCM (even though it was the same model) and need a brand new one. $300 later I was towing it back home with a flat battery, handprints all over the car and still not running!!

Not sure where to go from here?? Everything works except for the central locking from the keypad and no go. (Have bypassed the VATS in the PCM and just earthed out the Start wire to the BCM to get it back on the road but would like to get it all going again)
Have spent a fair amount of time searching the web but can only find some small bits and pieces on the BCM that haven't been much help

1. If the battery in the keypad stops working should the imobiliser still get turned off once the key is inserted and touches the key contacts?
2. Is the signal that gets sent to PCM to pass the VATS the same for all VR's?

anyone have any thoughts as to what maybe wrong and what I should check? (don't have much in the way of wiring diagrams either)

[The1]

vats is injector control on the ecu even with vats off the bcm will still retain control of the starter relay so only If a valid key is detected either by unlocking the doors with remote keypad or turning the key in the ignition so it makes contact with the ring will it engage the starter relay and let the engine starter turnover.

From the fact that you have replaced the bcm and the scantool could not communicate with it but it has power and some functions are working says wiring fault to me, i would be checking the data line wiring first, from there atleast you can get a scantool to talk to it and test the keyheads a tech1a scantool will be able to test the buttons and remote signal.

Even with a dead flat keyhead it should work in the ignition as the keyring provides voltage to the keyhead.

What level VR BCM do you have i might have something.

[benk]

Its a mid level BCM 789 (hard to find)

Yeah by disabling the vats got the injectors working and to get the starter working just ran the start wire going to the BCM to earth so basicly bypassing the anti theft in the BCM

That was my thought being a wiring fault somewhere? but can't find any diagrams anywhere to workout what goes where and the repair manual that I have doesn't even have the BCM in it....

[The1]

if you have earthed the starter it should crank and run then with vats off

[Holden202T]

see if any of this helps you.

http://www.oldholdens.com/temp/carstuff ... s/VR%20V6/

i have the complete VR factory wiring manual (some of the scans in this folder are from it) but its at dads, i can probably get more info out of it if that stuff isn't what you need.

[BPJ]

Benk, I don't suppose you are in Adelaide are you? If you car I can read the faults and check the keys.

Already covered but..

The battery in the key is only for the remote, a flat battery or even a removed battery does not effect the immobiliser side of things. When the battery is flat it's time to get a new key, I Locksmith with the right gear can read your existing key and get the security number from that which is needed to code in a new key head.

I had a customer today that was told by the dealer that if your battery is flat you can recharge it by leaving it in the car with the car on, this is not true, the only car that I know this is true is BMW.

[The1]

yeh the battery's in them are only CR's so not rechargeable, but key should work even with flat battery as key contact ring should provide voltage. Sometimes the key contact rings though need rebending to make good contact again with the key.

[benk]

if you have earthed the starter it should crank and run then with vats off

Yeah have done this to get it running again so I can use the car. Would still like to get it all sorted to get the central locking working again.

I live in Toowoomba qld so might be a bit far to drive BPJ lol

Pulled the key apart from the second BCM and found a broken solder joint on the earth and found that it had a replaceable battery in it so going to resolder the earth and get a new battery for it tomorrow and see how it goes.... fingers crossed

[The1]

lol, im in oakey, didn't know you were in Toowoomba. i have tech1a and vr gear, see how you go with the key.

[benk]

Yeah have only just moved here in the last few months
will see how it goes tomorrow