BCU - what were how
- Thread starter mrblonde
- Start date
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The Body Control Unit is the uber brains of the whole car....without it, it is just a giant paperweight.
The BCU controls and serves all the little other ECU outstations, and then pulls the whole lot together.
Most commands you give the car i.e. turning the lights on/off go through the BCU, the BCU then tells the Lighting Control Module to start the lights and control there functions...the LCM then reports back to the BCU that all is well, or if there is a bulb out, which the BCU will then display a fault on the dash as such.
It controls all the vehicle body functions like locking of the doors, security, immobiliser etc etc...
Think of it as the Network Server connected to all the other computers.
It is under the Passanger(?) front seat under a small cover....
It may not be the BCU causing a drain, unless there is another system keeping it awake all the time, on the P38 it was always the little RF unit....
On the L322 the Headlamp wipers have been known not to park properly and cause a drain....
Which fuse is the drain coming from, might help to narrow it down a bit!
The BCU controls and serves all the little other ECU outstations, and then pulls the whole lot together.
Most commands you give the car i.e. turning the lights on/off go through the BCU, the BCU then tells the Lighting Control Module to start the lights and control there functions...the LCM then reports back to the BCU that all is well, or if there is a bulb out, which the BCU will then display a fault on the dash as such.
It controls all the vehicle body functions like locking of the doors, security, immobiliser etc etc...
Think of it as the Network Server connected to all the other computers.
It is under the Passanger(?) front seat under a small cover....
It may not be the BCU causing a drain, unless there is another system keeping it awake all the time, on the P38 it was always the little RF unit....
On the L322 the Headlamp wipers have been known not to park properly and cause a drain....
Which fuse is the drain coming from, might help to narrow it down a bit!
Hi Saint
Hope you're sitting comfortably.....
Fuse 28 - headlight wipers, drain of 0.12a. Am thinking maybe the relay is failing and allowing current to pass? (Have tried resetting wipers both by pulling fuse, and physically reseating it on the wiper stalk)
Fuse 12 - FSR, ac and front seats etc, drain starts at 1.28a, then drops to 0.82a after 10 secs, then continually sits at 0.26a. Am guessing faulty FSR, but only changed it 10 months ago with a genuine LR one
Fuse 27 - glovebox light, interior light, clock, all BCU - drain of 0.47a when glovebox open, sits @ 0.13a when closed.
Any help will make you my new bestest friend forever
Hope you're sitting comfortably.....
Fuse 28 - headlight wipers, drain of 0.12a. Am thinking maybe the relay is failing and allowing current to pass? (Have tried resetting wipers both by pulling fuse, and physically reseating it on the wiper stalk)
Fuse 12 - FSR, ac and front seats etc, drain starts at 1.28a, then drops to 0.82a after 10 secs, then continually sits at 0.26a. Am guessing faulty FSR, but only changed it 10 months ago with a genuine LR one
Fuse 27 - glovebox light, interior light, clock, all BCU - drain of 0.47a when glovebox open, sits @ 0.13a when closed.
Any help will make you my new bestest friend forever
