Deano

How do I disconnect the TCU? Where is it located?

or_550i

TCU is in the trunk, next to the amp. The connector that has 'power' is on the bottom left; it has 54 pins. But the easier thing is to pull fuse 89 (pre-2005 - in the trunk) or fuse 37 (post-2005 in the glove box).

Deano

OK! I pulled the fuse to disable the TCU and yes, the stereo will now go to sleep. I'll keep the battery connected tonight and recheck it in the morning. Hopefully it will remain charged.

So I guess I need a new TCU. My car is a 2004 actually a 2/04. It one didn't originally come with bluetooth telephone capabilities. I bought and installed a phone cradle and that phone simulator (forget what its called) and gave it to the dealer to program. To my good fortune, the dealer screwed up with the programming and had to replace my TCU with a more modern one which didn't require the cradle or phone simulator, which I returned for refund.
Not sure what part number I'll need, but is it plug n play, or will I have to have the dealer do programming? Any idea where I should get one?

Thank you,

Dean

545felix

look up the part # on realoem and go surf ebay. make sure you get a part # from 10/04 or later (technically BT rolled out 09/04, but I'd add the month just to be safe) and you should be good to go. it has to be from an E60/61/63/64. No E46, E90, E53, E39, E83, etc.

nevrev73

I had this problem, I replaced the battery and then the problem continued.

Called out BMW emergency service and they di a voltage test on the car.

It turned out to be the IBS sensor was faulty.

He gave me some tips though on when and how the car goes to sleep.

If its auto gearbox, look at the P position or near the shifter and there will be an orange light.

If you dont have bluetooth vehicle then the car will go to sleep in around 20 minutes, If you do have bluetooth, it takes longer and around 1h 20mins before it goes to sleep.

If it is not this then it could be some other voltage drain such as a sensor somewhere gone or a light on in the boot.

A diagnostic check will tell you what part(s) are faulty.

Mine tunred out to be IBS lead. This was replaced under warranty, as was a new battery as it killed the other one!

Deano

That's interesting, 1h 20mins to sleep.

I had an appointment today and with the TCU fuse still out, I parked it for 1h 15mins, and the stereo was still awake. 1h 20mins seems like a ridiculous amount of time to keep three amplifiers hot. I guess I have to give it a little more time to sleep before I can put the blame on the TCU.

Thanks,
Dean

or_550i

Everything should sleep in 15 minutes. Most of the CANBUS traffic even stops after 5 minutes (usually - from what I've seen).

Deano

OK, to review:

The power for the stereo system is not going to sleep and all three amplifiers in trunk stay hot and the battery drains accordingly. After a period of time the light from the automatic transmission will turn off, but the power for the stereo remains on.

Why doesn't the stereo sleep? Pulling the fuse of the TCU seemed to work one time, but never after that. Do you know which fuse# will disable the headunit of the stereo?

I have an after market harness from Technic from the three series forums, which brings the connections from behind the stock headuinit back into the trunk area where I can get the signal wires into the main amp/signal processor (JBL MS-8) and send the amplified signal back into the stock speaker harness. The 12V power-on line from this harness goes into the MS-8, and the MS-8 provides a power output for the two additional amps.

An interesting symptom is about two minutes after I turn the car off, the stereo system delivers a "bump" sound, like a tennis ball has bounced off the car's roof.
This seems like stored energy is causing this. This bump will happen again if I reopen a door. I never noticed this bump before the draining problem, so I believe they are related. By pulling in-line fuses of the amps, I can remove the two other amps from the equation, but the bump remains, and is comming from either the MS-8, or through the MS-8 from the headunit itself.

Any ideas would be appreciated.

545felix

the bump is the CCC turning on and off. i would pull the 54 pin connector on the TCU at this point, perhaps the fuse isn't enough. the next step would be to disconnect technic's harness and diagnose the hi-lo adapter, or check the MS-8. if the light on the transmission is turning off, the rest of the car is going to sleep. it is sounding more and more like the problem lies with the MS-8 or amplifiers and not the CCC.

Deano

So if I pull the connector off of the TCU, and the stereo goes to sleep, then I should replace the TCU?

I remember there was a relay built into the technic harness. Is this the "hi-lo adapter?

Is there a way to determine if the amp that is built into the headunit is sleeping while the MS-8 stays awake? If I force the MS-8 to sleep it will turn off the other amps as well, but if headunit amp doesn't sleep I'll still have a draining problem.