BCM / Immobiliser Problems in VP

[pacey]

Hi, I know this has probably been mentioned before but be buggered if I could find any thread relating to these problems. Anyhoo, in last past few months the electrical side of my VP has gone downhill and I have been unable to find the cause. Lately, I have had trouble getting into my car let alone start it. Just to make things clear, I'll give a general history of the electrical problems in hoping someone can tell me as to what the problem is.

1. About 3 Years ago I attempted to install driving lights. I accidently joined the wrong wire causing the automatic light switch in the BCM to blow (its that switch that automatically turns the lights off when opening the drivers door), Hence rendering my headlights inoperable. Took the car to Holden and they said they could bypass the BCM and hook the lights up manually or get a new BCM for $400. I chose to Bypass the BCM.

2. Somehow got a short in the car to the point that is was melting and continuously blowing my fuses. One fuse and housing in particular was stuffed (the On Board Computer Fuse). I rewired it and replaced it with a new fuse housing. No problems for a while.

3. Another short, this time melted the ignition wiring harness causing numerous wires to fuse together and rendering my rear tail lights and parkers inoperable (headlights still worked thanks to the above mentioned bypass). Again, had to bypass the BCM (Done it myself this time). Eventually found the problem and un-fused the wires. Bypass no longer required.

4. High Voltage Problem Detected - Could hear the sound of sparking and crackling within the intake manifold (as though there was a major short). Took to Mechanic, told me that is was something to do with high voltage. Neglected to take it back to be repaired. Problem Still exists.

5. Interior Light Fuse continues to blow.

6. All of a sudden the car decided it didn't want to start. After fiddling around, I took the On board Computer fuse out. The Car started straight away. Turned off car, replaced fuse and started it without a problem. (This happened on about 3 other occasions afterwards)

7. Car alarm decided it wanted to go off at 3am in the morning. Flashers indicated that the bonnet had been raised. (Bonnet was secure). Ignored it as a one off. Happened again at 4am and 6am that same morning. Then again the next night. The neighbours weren't too happy. Decided to not use the alarm and just deadlocked my vehicle when leaving it anywhere.

8. This week, I decided to try out the alarm again. 1 hour later the alarm sounded. Turned it off and went back inside. Came back out and went to turn the immobiliser off (The "Press Remote" thingy) so I could start the car, Immobiliser didn't want to turn off. Took an hour for the immobiliser to disengage (my fingies are very sore after that). Now whenever the immobiliser activated, it takes forever to de-activate it.

My only thought is that the BCM is ummm, f***ed and the root of all problems but I can't say this for sure as I have no idea what the BCM controls and if it actually controls the Alarm and Immobiliser as well.

Any thoughts would be appreciated. I'm only on a coppers wage so I'm not looking forward to purchasing a new BCM if it's not the problem. Cheers

 

[HDT_aero]

firstly get a second hand BCM

second start searching in and out your car for dodgey earths id start with the engine bay and then the interior its quite possible the reason your bcm is stuffed is from a bad earth somwhere. As for the alarm and immobiliser is it a factory setup?? or an aftermarket install??

Id start by checking the wiring to the bonnet switch and id check the rubber is still on the bonnet that operates that switch. If your alarm thinks the bonnets open the immobiliser may not want to switch off and you will find that alarms will have a set amount of time or a set amount of ignition turns to disable the alarm without the remote etc.

Sounds to me like you are gonna have one hell of a time locting your problems, so if you were ever planning on upgrading to calais features then Id say rip out the entire wiring system and drop a calais one in it may just save you future hassles aswell if your car decides to work but you cant find a problem.

failing that a second hand BCM and a leccy should be able to solve your issues but could turn out quite costly for the leccy to fault find

 

[pacey]

Thanks mate, Unfortunately 2nd Hand Berlina LX BCM's are hard to come by. The Immobiliser and Alarm is factory fitted. The LX has the features of a Calais meaning that it was factory fitted with Electric Everything.

Just had a look for bad earths in the engine bay but couldn't find anything. I suppose the next step it to pull out the wiring harness under the dash to look for more burnt / bare wires that could be causing the problem.

Thank for the help.

 

[pacey]

Just Removed the BCM.... Had a look inside.... Circuits / Tracks are fried big time and just happens to be the circuits connecting to where the immobiliser wires go.

I can safely say that the BCM is the major malfunction as several circuits are blown. Looks like I'm going BCM shopping! Anyone got a spare?

 

[HDT_aero]

i start ringing around and looking in the paper/trader for wrecks stuff paying 400 big ones

 

[HDT_aero]

one more thing check that the earth wire for the bcm is a good earth you dont wanna put a new one in and it go poof

 

[pacey]

one more thing check that the earth wire for the bcm is a good earth you dont wanna put a new one in and it go poof

Cheers for the advice. :thumbsup:

Does anyone know how to bypass the immobiliser!

 

[joeallen]

I had a problem with my vp where the door locks and immoblizers didn't work properly. The dealer found the problem after 10 days in the shop.

There is a wire that supplies power to the passenger power windows and door locks. This wire had lost it's insulation over the years and was shorting to ground. Look behind the big ecm box in the passenger side kick panel. It will be hard to find. The dealer spliced in a new wire and voial! everything now works fine. You may need a repair book wiring diagram.

 

[pacey]

I had a problem with my vp where the door locks and immoblizers didn't work properly. The dealer found the problem after 10 days in the shop.

There is a wire that supplies power to the passenger power windows and door locks. This wire had lost it's insulation over the years and was shorting to ground. Look behind the big ecm box in the passenger side kick panel. It will be hard to find. The dealer spliced in a new wire and voial! everything now works fine. You may need a repair book wiring diagram.

Thanks, I'll give it a try

 

[tonykt47]

I have got the a similar problem with my immobiliser not turning off, cant start car tells me to press the immobiliser button, what is the BCM i am a newbie to commodores