[Reapur]

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[e90328i]

pretty sure your not supposed to connect from trunk battey but the posts under the hood.?

[enrita]

yeah connection through hood not trunk. you might have now a blown fuse?

[E90TiAgX]

Correct me if I am wrong,
was told to only jump start cars with engine off

[scottp999]

There are fuses in that little red plastic battery cover (battery distribution box). There is also a safety feature that causes a disconnect in an accident (Intelligent Battery Sensor). Maybe that was partially triggered.

Box is # 3 here - http://www.realoem.com/bmw/showparts...60&hg=61&fg=30

You should not jump start other cars from your battery. Use the + terminal and a ground under the hood.

IBS is mentioned here, sounds like it may be within the negative cable: http://www.e90post.com/forums/showth...26quot%3Bcable

[dsjr2006]

Originally Posted by E90TiAgX

Correct me if I am wrong,
was told to only jump start cars with engine off

That is the exact opposite. It's almost impossible most times to jump start a car without the engine running.

[kfrazie1]

Looking in the Bentley manaul, looks like for an n54 335i, the fuse is F7 and its acutally 40 amps. Also, looks like the jump terminal is somehow connected to that fuse too...

[j1gilles]

You would like to think that a 50k+ car would have fail safes in the event someone did not read the owners manual on proper jump starting. Most of the fuses that would have blown in this incident would have taken out move than just the water pump... Although the "smart" battery in our cars can act a little goofy when its messed with.

[Reapur]

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[scottp999]

Originally Posted by Reapur

So just a question about the battery distribution box / fuse. Am I correct to assume that the fuse is built into the box and isnt a typical replaceable fuse? So in short to replace the fuse you just simply buy a new distribution block?

I can only speak from experience, for my April 2007 built 335. When you order a new battery distribution box (i ordered one from tischer about 3 yrs ago) the fuses (more than one) are not included. Best bet is to call or IM tischer parts on your model and build date and see what they say.

[335xi Kevo]

Originally Posted by Reapur

Hey all,

Need some guru help here ASAP.

Last Friday I bought my 2009 135i, on Tuesday night I am arriving home from work and a neighbor asks me to help boost his battery, I say sure because I'm a nice guy. We hook up, me to terminals in trunk and him to his battery. When he connects his terminal there's a somwhat large spark. My high speed fan kicks in on the radiator and I get an overheat warning. Something's gone wrong with the electric water pump. Coolent boils over from the reservoir and the car goes into limp mode. The next day I goto BMW dealer and they don't know what the issue is. They suggest replacing the water pump and thermostat and it doesn't work. They're at a loss. Diagnostic says that there's no power to water pump, yet the 50 amp fuse isn't blown under the hood next to the DME. They suggest the DME may be fried and it will cost 2000 bucks to fix.

It all sounds very fishy to me what could it possibly be? I suggested the relay ontop of the battery in the trunk as a possible culprit and the service manager scoffed at me saying that BMW would never run wires all around the car like that to supply power to te water pump when they could draw power right from the DME under the hood.

Sounds like a load of bullshit because power has to come from the battery and there's no way a 50 amp fuse would be supplying power to a water pump right from the DME. I think there's something wrong in the trunk preventing power from being sent up to the engine bay for the DME or water pump.

Please keep in mind I'm new to the platform and my knowledge base at this point is fairly limited. I am however mechanically inclined and basically built my s2000 from the ground up. I understand that BMWs have a lot of unessisary electronic stuff compared to most other brands but the fundamentals should still be the same.

You have a warranty. Have then fix it. If you just bought it theres that 90 day used car lemon law warranty.

[onebadmofo]

Whatever you do don't tell dealer that you helped someone jump the car.

[Reapur]

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[Reapur]

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[scottp999]

Excellent.

[Reapur]

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[cwarren]

[klipseracer]

Originally Posted by Reapur

Yup, car is totally fine now after replacing the fuse relay on the battery.

chalk one up for the internet and a fail on licensed mechanics ...

The red plastic cover over the battery is a pyrotechnic charge. It fires during an accident to disconnect your battery from the car to prevent fires and other issues. It is known to not disconnect all the way leading to all kinds of DME wackiness. The posts under your hood are where you are supposed to jump from, but I'm glad you have it worked out.

EDIT: As a side note, if you are the one being jumped, you can only do it from the trunk if the pyrotechnic charge is blown. I had my car on a moving truck and we were stuck there for 2 hours trying to figure out why I couldn't put the car into neutral.