Battery drain: E39 not entering sleep/hibernation mode

[Simca 49]

I've googled it all. I've read it all.

Everyone tells you how to test if the car is going into sleep mode, no one really tells you what to do when it's not. Everyone is giving vague answers, and every web forum seems to have their own separate ideas.

I have left all 4 doors closed, boot closed, glove box closed, with the car unlocked, and come back and still had the shifter light on.

I have left all 4 doors closed, boot closed, glove box closed, with the car locked, and come back and still had the shifter light on.

From what I have gathered it is likely something to do with the General module. From some info I have gathered that the car will not go into sleep mode if the general module prevents it from doing so. There are likely two things that can be causing this I think, either a faulty general module, or something like a door or boot module which is still signalling over the I-Bus system even after the car has been shut down. If I am correct every time the General module receives a signal, it resets this timer.

I have also read some stuff about the FSU, but I feel like this is a red herring, as that seems to contradict the other General module info. Some people also mention the CD changer, my car does have some funky stuff going on with the amp/CD changer/aftermarket Ipod adaptor in the boot, but I am not sure how this ties in with the I-Bus system. I assume there could be potentially signals that go to the radio over I-Bus from the CD changer/Ipod adaptor stuff, but someone please let me know if they have an idea if it does. (I actually wrote this and then ripped all the aftermarket stuff out, including factory amp for now, and it did not make a difference)

Essentially I am wondering if anyone knows how to diagnose this without just replacing parts at random. Is there a way to "read" the general module, and gather where it is getting signals from? Can I just one by one unplug the modules connecting to the general module to see which is the culprit? (and if so what can I test?).

If I do end up replacing the general module does it just plug right in or do I need to get it mated to the car (and how)?

Here's my in post update that takes place about 2 hours after writing the first part:

Checked some wiring stuff on Newtis. I do definitely believe that the general module is keeping the car awake, since pulling relay 4 immediately shifts the car into sleep mode (shuts off lights and also the fan inside the HVAC panel which was staying on), and relay 4 feeds directly into the general module. Everyone online keeps talking about I-bus stuff, but newtis only really brings up K-Bus on the general module stuff, although it does make mention of I-Bus in passing outside of the wiring diagrams. So much I've figured out so much I've still to find out.

Low key just considering putting a timer on fuse 4 that shuts off 15 mins after the key is taken out, or a relay on the I-Bus connection that only switches on when the key is in the ignition is on.

Otherwise I guess I'm just gonna do a bit more reading and see what I can try to unplug, issue is just the 16 minute wait time to check if the car's gone to sleep, really eats into the day very quickly.

[Neal 540]

The cd changer power connector also has ibus wire. The audio system can keep the car from going to sleep , but it’s normally via telephone module thinking a phone call in in progress which in turn keeps the tuner module running. Tuner module controls the power on / off signal to both the amp and aerial amplifier. If your car has a telephone in the armrest type disconnecting the cables to it under the arm rest. However, if you’ve disconnected the tuner module and amp I doubt this will be causing the ibus bus to stay awake,

[Neal 540]

Have a read from page 18 on the I/K bus for a further understanding 

http://www.e38.org/bussystem.pdf

 

 

[aja540i 1906]

Mine was doing this when the heater  motor hedgehog resistor failed, the fan was staying on and stopping the car from sleeping, easy enough to unplug it and see if it changes anything.

[Kiwi_BMW 89]

I have an intermittent issue with this also, I can park the car and come back several days latter and everything is fine, yet occasionally when I do this I come back a few days latter and the battery is flat.

I found my resistor for the aux cooling fan was crook, so replaced that and the problem went away for a few months, then it started happening again, I replaced the heater fan resistor and it seemed to remedy the battery drain.

Six weeks latter I went and started it and took it for a drive, parked it up again, car locked, came back a few days latter battery is dead flat again.

Quite frustrating, I've fitted a battery disconnect to the neg terminal and when I park it up I just unscrew the disconnect and leave the boot closed but not latched.

How do you tell if a manual E39 is going to sleep or not, it doesn't have the light beside the shifter 

[Simca 49]

9 hours ago, Kiwi_BMW said:

I have an intermittent issue with this also, I can park the car and come back several days latter and everything is fine, yet occasionally when I do this I come back a few days latter and the battery is flat.

I found my resistor for the aux cooling fan was crook, so replaced that and the problem went away for a few months, then it started happening again, I replaced the heater fan resistor and it seemed to remedy the battery drain.

Six weeks latter I went and started it and took it for a drive, parked it up again, car locked, came back a few days latter battery is dead flat again.

Quite frustrating, I've fitted a battery disconnect to the neg terminal and when I park it up I just unscrew the disconnect and leave the boot closed but not latched.

How do you tell if a manual E39 is going to sleep or not, it doesn't have the light beside the shifter 

I think just leave a door open, interior lights should go out after 16 mins as well. Otherwise put a multimeter between the battery negative and the chassis and check if its drawing less power after 16 mins.

[Simca 49]

On 9/15/2022 at 3:55 PM, aja540i said:

Mine was doing this when the heater  motor hedgehog resistor failed, the fan was staying on and stopping the car from sleeping, easy enough to unplug it and see if it changes anything.

I'll give this a shot as well!

 

On 9/13/2022 at 11:02 PM, Neal said:

Have a read from page 18 on the I/K bus for a further understanding 

http://www.e38.org/bussystem.pdf

 

Thanks for the info mate. No phone in the car, a guy on facebook told me apparantly there's a way of reading the I-Bus system over USB so I will give that a shot if I can figure it all out. Maybe it's a faulty GM but I really don't want to replace it since it sounds like a fair bit of admin.

[Neal 540]

Yes , one of these need to be tapped into the top bus wire white with yellow from memory. Also needs 12 volt and ground.

A person in bimmersport wrote a program to read the ibus and do some basic programming about 10 plus years back “search “jochen ibus”

I think there are also some more recent programs also 0n gethub.

https://shop.ibus-app.de/en/

Edit

nav coder

http://www.navcoder.com/

 

 

Edited September 16, 2022 by Neal

[Simca 49]

Hate to bump this post but as an update to my post this is fixed now!

I literally just went through the car with INPA and reset every single code on the car I could find, and it seems to have miraculously cured it.

[_ethrty-Andy_ 2132]

yes seeing increasingly now in e38-e53 era of BMWs that these modules are all still running strong but do randomly throw codes that do strange things when present. so happened to just post that on another thread too. they are all getting to the age well beyond what they were designed to last.