if you disconnect the cable in the back (IIRC---its the positive cable due to the red cable color) that would hence open the hot battery bus circuit and thus...its disconnected.

 

it's easier to disconnect the negative terminal. There is a little popup cover over the negative terminal just for this purpose. To get to the positive terminal, you have to take off the whole battery cover.

 

always remove negative (brown, on a bmw) first. For something like this, you only need to remove the negative cable, that takes the power out of the system, no need to remove both.
Mike

 

wooops...it was negative that i ment. I guess I dont deserve another m5.

 

You want to remove the negative "-" first for safety reasons. For example, if your metal wrench is on the "+" terminal and it touches any metal part of the car ("-"), then you could have any of:
1) battery explosion (I've seen this first-hand)
2) fire
3) burned hands
4) lots of sparks and a pow that will scare the bejeesus out of you

Now if you disconnect the "-" first, you can touch the metal car with the metal wrench and nothing happens (they're both "-").

One last bit of advice - have your key fob handy. Disconnecting/reconnecting the battery:
1) could set off the alarm (and it doesn't matter that the battery is disconnected)
2) could lock your doors


Cheers!

 

another thing worth mentioning is to wait a couple of minutes after opening the trunk before you disconnect the battery. I believe the nav computer fires up when you open the trunk, and will power back down in 90 seconds. I've read that you can damage the nav computer if you disconnect the battery while it's running.
Mike

 

okay guys, thanks! i think i understand... so the cable actually connected to the battery in the trunk is the negative (the one under that little plastic clip cover)? or is that the positive? if so, where is the negative located... somewhere under the hood?

what about touching the positive and negative to drain the power in the cable? not necessary?

thanks for the nav tip... wouldn't have thought of that on my own...

-keith

 

Here is the note about the Nav power from Bluetooth installation instructions on bimmernav.com:

ALWAYS disconnect BATTERY before working on the electrical system in a BMW. Most importantly, you should ensure that the navigation computer Power light is OFF before disconnecting your battery. BMW states that if the battery is disconnected when the navigation computer is on you may damage the nav computer. The important thing to keep in mind is do not disconnect the battery if the power light is on your navigation computer.

 

okay guys, thanks! i think i understand... so the cable actually connected to the battery in the trunk is the negative (the one under that little plastic clip cover)? or is that the positive? if so, where is the negative located... somewhere under the hood?

what about touching the positive and negative to drain the power in the cable? not necessary?

thanks for the nav tip... wouldn't have thought of that on my own...

-keith

GreekM5,

The negative is on the right and the positive is on the left side of the battery. Like the previous poster indicated it is more difficult to disconnect the positive side because you have to remove the cover.

Everything can be found in the trunk. No need to look under the hood. I hope that helps

Bob

 

okay guys, thanks! i think i understand... so the cable actually connected to the battery in the trunk is the negative (the one under that little plastic clip cover)? or is that the positive? if so, where is the negative located... somewhere under the hood?

what about touching the positive and negative to drain the power in the cable? not necessary?

thanks for the nav tip... wouldn't have thought of that on my own...

-keith

Keith,

the one underneath the little flip up is the negative (unlike what my first post stated..i just couldnt remember) and that is what you should undo. Its going to take a 10mm wrench or socket. Isnt it handy that they include one in the trunk kit?

 

thanks everyone... worked like a charm.

i know it was nothing "major" but i was afraid of messing something up with something as simple as disconnecting a battery (which i probably would have done to the nav if i hadn't had asked the question here)... again, thanks!

ps. woo hoo, post #700 :biggrinbounce:

 

GreekM5, what probs were you having with the DICE?

 

another thing worth mentioning is to wait a couple of minutes after opening the trunk before you disconnect the battery. I believe the nav computer fires up when you open the trunk, and will power back down in 90 seconds. I've read that you can damage the nav computer if you disconnect the battery while it's running.
Mike

I always wondered why I heard the NAV discs running or turn on when I first pop the trunk/boot lid Thx Mike

 

I always wondered why I heard the NAV discs running or turn on when I first pop the trunk/boot lid

It's set that way to reduce the boot up lag time when you first get into the car. It gives it a bit of a head start. If they didn't do that, people jumping into the car and wanting to set the nav and take off would get frustrated waiting. As it is, there is a bit of a wait anyway.

 

It's set that way to reduce the boot up lag time when you first get into the car. It gives it a bit of a head start. If they didn't do that, people jumping into the car and wanting to set the nav and take off would get frustrated waiting. As it is, there is a bit of a wait anyway.

I guess if you don't pop the trunk before you get in the car your scr*wed and have to wait anyway:confused2

 

Thanks, guys/gals.

I knew about the battery terminals, but didn't know about the NAV light having to be OFF before disconnecting the battery (never had a NAV unit on another car).

One, day in the future I would have certainly replaced the battery without concern for the NAV light ...

Whew ...

 

GreekM5, what probs were you having with the DICE?

LFC09, my unit was not importing/displaying the ID3 tags properly... AND my stereo would switch from CD to tape/radio randomly... so i'm trying a new unit.

 

GreekM5, PM sent re ipod CD changer issues.

 

Bumping this old thread because it would've helped me a few months ago when I disconnected my battery before the nav light turned off and fried my nav computer.

I've noticed a lot of new members recently, and a few threads about people having issues with the nav.

Just so you don't have to read through...

1. Open your trunk
2. Wait for light on nav computer to turn off
3. THEN disconnect battery.

 

One of the most useful bits of trivia I've learned for a while, so many thanks for bumping this. I would not have considered waiting for the nav computer light.

 

:grinyes:

 

DIY battery replacement which obviously includes how to disconnect.

BMW E39 M5 Battery Replacement - YouTube

 

I have worked on cars my whole life and I have never had to wait for any lights to turn off before disconnecting the battery. I realize that a lot of you already know what to do. I bumped this in case there are members, new or old, that didn't know so when they go to do any work that requires disconnecting the battery, it will go smoothly. If you don't need the advice, this thread is not for you.

 

Ok so the Alarm enabled itself somehow while I was messing with my blown amp in the trunk, when I disconnected the neg battery terminal the alarm went off! is there a backup battery or is there just a security measure to keep the alarm powered?

 

Woooow

 

Joke