Power Distribution Module

[RichardSA]

Hi All,

Has any body got any advice on how to open the PDM unit in the luggage compartment in order to add a positive cable point. In my vehicle it is the blue/white box behind the spare wheel with the power cables entering and exiting.

[Weasel]

The cover pretty much just pops straight off towards the rear of the vehicle, Just has a couple catch tabs holding it on that are easy enough to release. And any empty spots have the mega-fuses already installed so you can just hook up to one of the appropriate size. I wired the pos+ wire of my amp directly to there on mine, worked out perfectly.

[RichardSA]

Thanks Weasel - I'm also doing an amp and wanted to avoid wiring directly to the battery. I figured that the unit was put there for a good reason.

[masq]

I've been doing audio installs for over a decade now, and I've always tapped the power directly to the battery. But with all the fancy schmancy electronics in newer cars, I'm going to have to doubt myself a bit and ask why you wouldn't want to tap directly to the battery?

[wullaby]

I think because the PDM is fused, it means no inline fuselink is needed when hooking up, vs battery hookup you need that additional purchase or item.

[Weasel]

@masq

On modern BMW's the battery terminal is already cluttered with all kinds of stuff including a pyrotechnic charged safety terminal. And on this model just a couple feet away is a power distribution block powered directly from the battery with a 2 gauge wire that usually has open spots with 60, 80 or 120 amp fuses open and ready to use... Why WOULDN'T you want to hook up there. And to top it off, the main chassis ground is right there too just waiting for a new terminal to be bolted on.

[RichardSA]

It was put there for a reason. I used the PDM for my subwoofer amp power connection - found a spare slot, put in the required 40A fuse - perfect!

[masq]

Thanks for the answer. I didn't know there were open slots that have 120 amp fuses on them already. Sounds like it really would be the perfect place for me to tap my 1100 watt inverter.

Are there diagrams that show where those slots are? Didn't see them during my search on the forums.

[RichardSA]

Masq,

Mine is a 2005 model and I don't know if earlier models had the PDM. On mine it is situated behind and to the left (if looking into the luggage compartment from the rear) of the spare wheel. It is a Blue box with a White cover that pulls straight off as Weasel has described. You'll find the existing fuses and spare slots in there.

[masq]

I have a 2007 model. If I can't get examples, then I plan on just ripping out the panels to follow the wires to the PDM. From there, I'm sure I won't have a problem spotting out a 120 amp fuse...

I'll try to take pictures.