Strange electronics problems after battery change

[X5Sport]

A request to all of you electronics wizzards - I know we have a few.

Although this is not strictly an E53 problem as it's occurring on a 2005 E46 convertible, there are similarities with the electronics systems that might mean you folks can help. The car is fitted with the full MkIV nav system, OBM and TV function plus a CD changer and MD player in the head unit.

Here's the situation. Battery changed on the car as the old one was not holding its charge. Upon reconnection the following entertainment system hardware no longer worked:
Nav Audio
Power function on left side of head unit (orange LED is out), and all of the buttons on that side.
No Radio or associated functions.
No CD changer - cannot eject disc cartridge either.
No MD - not selectable as the LHS buttons don't work on the head
TV Audio.


The Nav and TV receivers both work (the TV receiver was as deaf as a post and only saw a fraction of what it should - but is now fine) but there is no audio - presumably because the amp is off and won't switch on.

I have done the following:
Checked fuses 7 & 41 - I think these match the E53 as well - both are fine and there is 12V on the two circuits. No other fuses are listed for the CD changer or radio. I also pulled the fuses for the OBM system and checked them.

Interestingly the main 30A fuse for the roof motor was blown - though how a battery change caused that I can't work out.

I have also disconnected the new battery again, touched the two leads together to kill any stray voltages and then reconnected. It made no difference, but was probably worth a try.

I believe frome reading info on this an other sites that all the devices must 'reconnect' via the iBus. I have no way of checking that this is happening. Has anyone else ever come across this, or knows where to look?

The indy dealer has had the car back. They took all day working through the electrical system and got the audio, radio, Tv Rx now at proper reception on both analog and digital going, but the CD changer is still down. The dealer won't say what they did or found, but I think they're just as frustrated having pored over the wiring diagram. Where does the CD changer get its power from? Suggestions? Clues? What really happened and if it happens again what do we do?

I need to change the battery on my E53 soon too as it's 5 years old and a bit dodgy in cold weather and I don't want to have the same issues with mine, hence wondering what to do to avoid the same thing on mine?

[Laurence]

The CD changer has an on board fuse at the rear of the unit (the purple fuse in the picture below)



It would be worth pulling it out and checking it.

It does seem odd that you've had so many problems installing the battery. I have disconnected mine a few times without issue.

[X5Sport]

Thanks for the heads up.

The battery has been disconnected before and there's never been an issue - so I'm just as surprised. I'm almost wondering if there was form of static discharge as the battery was changed or something really daft like the replacement went in backwards for a split second - though I suspect that would have done much more serious damage!! The beemers are supposed to 'self-recover'.

That being said, my E53 just came back from having it's transmission repaired and it had lost the remote locking capability from one of the keys. It had a dead vehicle battery too. Remote locking on all keys fixed now thanks to this site - you folks rock

The latest try is to fit an OEM battery on the E46 in case that works - I can't see what difference that's going to make, but if it works.........

We'll get that fuse tracked down too. It's not listed on the fuse card and I never thought to look - mind you it means taking half the boot trim out to get at it unlike the 'X's little rack.

EDIT - Perfect. That was the little beggar. Not listed on the fuse card, nor known by the indy dealer. Spot on. The only mystery now is why all this happened when all they were supposed to have done was take one battery out and put a new one in. I don't suppose we'll ever know now. Thanks again. The membership scores another 100% success story.

[Laurence]

Glad your all sorted.
It does sound as though the battery was installed incorrectly. This would certainly cause the CD player fuse to blow - most devices have protection against incorrect polarity and these function by causing the on-board fuse to blow.

[Christiano]

I had the same problem. Radio dead after a bad battery problems. I tried to recharge one night but after 2 starts, the battery show problems again. The start was "heavy", slow and the internal lights blinks when reavings.
Go to the dealer and bougth a new one.

All issues solved! Car run like a champ and radio back to live.

Chris, 4.8is 06