Battery drain

[BimmerFlyer]

Hi guys, need some guidance with my ‘97 740il,
Battery going dead, been doing some reading and trouble shooting, and this is where I am now...
Car did not always go to sleep, narrowed it down to someting to do with the powering down from a full up and running status.. (ie, waking the car up with key fobs would not induce the fault).
Made a cable contraption so I could hook up my amp meter, start the car, shut it off and watch the power down power draw and not blow up my Volt meter, but anyway..
finally was able to catch the car in a “ not going to sleep” status, ampdraw around 700 mA ...I found that 600mA is normal”standby to go to sleep”draw, 24mA is sleep mode ..
noticed with the car off, could still hear a small fan running in the Climate controll panel, and the heater valve under the hood would cycle once a minute....
Started pulling fuses when “refusing to go to sleep” status and found that fuse 11 under the hood(IHKA) would significantly drop the amperage... all this well after 16 minutes when it should have gone to sleep..
I have also seen with my own eyes that even when the car does go to sleep, it can wake itself up..shifter light came on by itself...
my questions are, since there are so many modules and busses talking to the IHKA panel, is there a good way to start eliminating? And what modules can actually “wake up” the car after it has gone to sleep?.Is there a list of , in what order the modules shut down? I can see the various modules power down, it be nice to know what they are... If I know in what order they shut down, I might be able to determine to see which one gets stuck...
Have a good battery that is fully charged that I am working with..
i have a code reader (Autel), but I can not get in very deep into some of the BMW modules...
Pete

[jclausen]

One of the more common items that would cause drains is the nav compiter in the trunk. You can easily see if your czr gropes to sleep by keeping in eye on the p light on the shifter of after 20-30 mins that thing has not gone off you have something keeping it awake any after market stero stuff installed

[Mayorchuck]

Sounds like you have a REST, vs. MAX, IHKA. I've never used it but if you have the REST button pushed, I believe it continues to run your heat after the car is turned off, for a period of time. QSilver7 has posted info on it several times here. If it's not shutting off after a short time, esp after the 16 minutes, it may be an issue with your IHKA.

Tim has a good write up on isolating battery drain if you haven't seen it.

https://www.meeknet.co.uk/E38/E38_Battery_Drain.htm

[Timm]

The trick is not to remove fuses - but to measure the voltage across them as this traces current without disconnection and does not reset the module. The General Module 'wakes up' a few of the modules - but some have their own timing. If you see the gear indicator lighting up on its own then check the door handle microswitches as they are an input to the General Module to activate a number of things such as the IHKA, interior lighting etc.

[BimmerFlyer]

Thanks guys, no Nav, no aftermarket anyhing... When the Park light comes on by itself, nothing else visible wakes up, IE, no interior lights etc....I thought of the recirc function as well, but could not see anything on the panel that is was active..
I did indeed see Timm’s write up and have used it for troubleshooting......I do have a spare IHKA panel from a 1999 post Face lift laying around, I presume they are all interchangable.... I will swap that in and see if it makes any difference..
will report back...
Pete

[BimmerFlyer]

Looks like the IHKA panel was indeed the cause of the car not going to sleep.... signs were a draw on fuse 11 under the hood, when off after 16 min, the occasional (every 30 seconds) clicking of the heater relay on the firewall some of the time..and the continuous running of the cabin temp sensor fan thingy in the panel itself.... recirc was off....and the strange thing was, it would actually wake itself up... the shifter light would be off, and without me doing anything or even touching anything, it would come back on...swapped panel out with a spare, I hope this is indeed it, so far so good....these intermittent electical issues,what a pain...
Pete...

[Timm]

Well done for getting this far - I have heard of the IHKA panel causing this problem, but only once before - usually it is the General Module.

P.S. Just remembered - on the occasion that the IHKA was the problem, it was because the panel had been replaced and not coded to the car.....

[BimmerFlyer]

Well Timm, I spoke too soon..%#@(&^), during testing yesterday, after replacing the IHKA panel, it went to sleep 7 out of 7 times.... didn't wait around to see when I put it in the hangar last night.... this morning, it was awake...@(&%!&%!.. starting over again..
Blew up my mA meter, waiting for some new fuses to show up.... so just playing with mV for now...... In a further note.. I did hear and feel one of the 2 heater solenoids on the firewall click at 1 minute intervals... very strange, not a very loud or pronounced, but you could sure feel it.. , car has been off, engine cold, everything inside quiet and calm... Recirc is off as far as I can tell... Does anyone know what drives those solenoids ? figured it would be the INKA panel, but with it been switched out that would be very strange indeed..More research to be done...will start digging into the manual some more... Standby for further updates...
Pete

[BimmerFlyer]

Well, did some reading on the whole INKA system, found a nice 50 page PDF describing its workings and actions..Looks like, as Time said, any replacement panel needs to be correctly coded to the car, what I did not do....but it all seemed to work nonetheless .. still baffled on why the solenoids would be cycling after the car has been of for 1/2 hour....with 2 different INKA panels installed...looks like those solenoids are direct drive from the control panel..... going to do some more testing..
Pete

[Timm]

You can't use the mA setting to measure current drain - it will just blow the fuse each time - and the series resistance is enough to upset the electronics. More information regarding meter settings in this:

https://www.meeknet.co.uk/e31/E31_Ba...iagnostics.htm

[BimmerFlyer]

You can't use the mA setting to measure current drain - it will just blow the fuse each time - and the series resistance is enough to upset the electronics. More information regarding meter settings in this:

https://www.meeknet.co.uk/e31/E31_Ba...iagnostics.htm

Yeah, understood Timm, it was poor wording on my part.. Blew up meter fuse by turning key to position 2 with the meter still hooked up between grounds anyway, new fuse installed, and back in business....
I do have a question.... I have several fuses under the hood that have power while the key is off and the car is in Pre sleep mode... about 750mA or so.. fuse 11 and 26 for sure.... If I wanted to see what is keeping the car awake, would removing one of those fuses have an effect on the cars ability to go to sleep? ... I.E.would the missing "data" from whatever is powered by those fuses prevent the car going to sleep... Both those fuses are feeder CB's and have a lot of stuff on it and it would be nice to narrow it down a bit..
And thanks for the help, chasing electrons is not my strong side..
Thanks
Pete
PS, thanks for that link, lots of stuff on there for sure...

[BimmerFlyer]

Still chasing this, but I have answered my own question... yes, the vehicle will go to sleep with those fuses removed..I did get all the codes erased today, will read them again in a couple of days and see what pops up...
Pete

[BimmerFlyer]

well, Timm once again saved the day.... As reported I suspected my original INKA panel went bad..(cabin temp fan kept running for a long time and heater valve kept cycling, even with car cold).
So I replaced it with one out of a post Facelift one I had laying around.. everything seemed to work, but car still did not go to sleep correctly.. Timm reminded me that the unit needed programming... Took car to a Indy guy, reprogrammed unit in about 10 seconds, pulled all codes.... and all is well.. car behaving like normal and all seems well... 15 out of 15 times so far that it goes to sleep normal..
So anyway, Thanks Timm, and as a reminder, program your INKA panel if it needs replaced.. and looking thru the electrical wiring diagram, that panel just about ties to every system in the car...
Pete