VT 11 current draw problem

[pman92]

Hey guys,
Have a VT 2 clubsport 5.7 in at work.
Customer complaining of battery always going flat.

Has a current draw of 200mA, I'm under under the impression around 50mA is the maximum.
Have found the BCM is keeping the interior illumination relay energised at all times. Even half an hour after locking the doors and walking away the relay is still energised.
The current draw drops to around 80-90mA with the relay removed. No interior lights, boot or glovebox light etc are going. Just the relay that powers them.
I've also found the scan tool will still communicate with the BCM half an hour after key off.
The relay goes on and off perfect with an actuator test via scan tool, but always defaults back to on.
Door open switches are all working.

Is it possible the BCM is meant to be powering down and isn't?
How long is the interior illumination relay meant to stay energised after you lock the doors and walk away?

Any advice appreciated
Thanks in advance

[Gareth]

Its been a while since I've played with a VT and this issue, but here goes...

Off the top of my head, BCM power saving mode cuts in after 1 hour?... (Yoda might be able to confirm)

There must be an external cause of the 'relay on' scenario, I've seen water in door looms cause this.. I'd be looking for the earth that will be triggering the relay (and yes, I know you can over ride this with the scan tool).

Now a word of warning here, Don't attempt to replace the BCM, the vehicle will lock down and will only be able to be reactivated by a Holden dealer.... Google HSV ESS if you don't know...

[jenko]

if it has aftermarket alarm system check what that's been wired to

[pman92]

I've disconnected an aftermarket 'corrosion prevention' gimmick which has dropped off another 40mA.
Still have about 160mA though.

I'll leave it sitting for a couple of hours and see if it changes after it enters power saving mode, if it ever does.

The relay receives constant 12v, and the BCM is the earth that switches the relay on. I've confirmed there's no loom fault because as soon as I disconnect connector B from the BCM (which the wiring diagram says it goes to) the relay de energises and there's still 12v to one side of the solenoid.
So the BCM is definitely responsible for holding the relay on, even if there's something else causing it to do that. Or maybe it is meant to do that until it enters power saving mode, which would make sense.
The relay only supplies power to the dome light, glovebox light, boot light and ignition barrel light.
IE. If someone left the glovebox open, the glovebox light would be turned off as soon as the BCM entered power saving mode and switched the relay off preventing a flat battery.

[MAGP]

Try the electric aerial. Seen that happen a few times over the years.

[Jayme]

The BCM Battery Saver Mode provides vehicle battery protection (through reduced current consumption). After a
programmed delay period (shut down timer) the BCM -:
1. De-activates the interior illumination relay which supplies battery voltage to all interior dome, ignition lock, glove
and boot lamps, protecting the battery in the event of-:
A lamp mistakenly left on (ie. door open) or a faulty illumination circuit or component causing excess current
consumption.
2. De-activates the power window relay (separate from the normal power window off delay function).
3. Disables BCM inputs normally not required with the ignition in the ‘OFF’ position, to reduce its own current
consumption.
The battery saver delay period has a default value of one (1) hour, however can be set from 2 to 255 minutes via
TECH 2. The delay period (shut down timer) is initiated when the ignition is switched to the ‘OFF’ position.
Whilst in Battery Saver Mode, the BCM is ‘woken’ up when:
1. The bonnet, boot or any door is opened.
2. The BCM receives a valid RF key ‘LOCK’, ‘UNLOCK’ or ‘BOOT’ signal.
3. The Ignition is switched to the ‘ACC’ or ‘ON’ position.
4. The doors unlocked via the driver’s door microswitch.
5. The deadlock switch is activated.
6. TECH 2 is communicating with the BCM.
7. The headlamp switch is cycled from ‘OFF’ – ‘ON’ or ‘ON’ – ‘OFF’.
8. The rear compartment lock switch, located in the glove box, is activated.
9. When the alarm is activated.

[Holden202T]

im not sure how relevant it is, but in my adventure of fitting complete VS Commodore wiring loom to the Bedford i have found that if things like door light switches are not working properly the interior light will stay on forever

it might be worth removing the door light switches and disconnecting the wire to them and see if this fixes the issue ..... (grounding the wire completes the circuit)

i found that when it works properly and you lock the car with the key then the light goes off after about 20 seconds in the VS anyways....

also keep in mind if there is a boot light, might be an issue there.

[Holden202T]

just had another thought, i had a feeling the VT has the same headlight switch as the VS, which has a slider on the side to dim and brighten the dash, and if you flick it right down it puts the interior light on doesn't it ? might be that ?

[pman92]

I waited the hour and sure enough it worked.
Current draw was then 50mA with the corrosion protection device disconnected, and 90-100mA with it connected.

It may be the combination of the extra current draw from the corrosion protection thing they have fitted and the fact they don't use the car every day and do short trips that's causing the flat battery.
Battery is near new and in good condition.
Alternator is charging fine.

Sounds like it's time to drive the car more or get a trickle charger.

[j_ds_au]

Despite the power saving mode switching off the interior illumination relay, it should switch off much earlier, per the courtesy light timer. You still need to check the door switches and wiring, as suggested above.

Joe.