[douglee25]

Car - 2008 e90 M3

Long story short, I've honed in that I have a battery drain issue going on with my car. Using a meter I've found that my car draws 0.5 amps after full shut down.

I've used ISTA-D to run an analysis and I am gathering data to hone in on the issue.

I can't say with 100% certainty at this point, but the data is leading me to believe it's the CAS module not fully shutting down.

I've updated the software in that module and no change.

So with that said, are there some typical items on this car that would typically cause the CAS module to not shut down? Door switches? Hood switch? Etc?

This have been probably been one of the most frustrating issues to troubleshoot for me ever!

Thanks

[Sensible_]

This is a nightmare to diagnose. Some really the list of possible reasons is endless. I've come across battery drain due to:

- improperly registered battery.
- TCU in boot not shutting down.
- Comfort Access module fault or even door handle fault related to comfort access. Possibly even key fobs.
- CAS fault
- EGS shorting out
- any aftermarket devices installed?

The only way to really nomad row it down is to start pulling fuses. Let the car go into sleep mode, you can fool it by wedging door / trunk / bonnet clips. Connect a multi meter in series to the battery, then start pulling fuses. After each one you may have to wait for car to go back in sleep mode. Have someone monitoring the multimeter when fuses are being pulled and see if there is any change in current...

[douglee25]

Ok so I've been there and done that... here's where I'm at -

My response will be somewhat limited on technical details because I don't have the info right in front of me.

1. With the meter inline and the car off, the car is drawing 0.5-0.6 amps while in sleep.

2. Fuse #28 - 5amp (cut off fan relay under the passenger seat and carpet) that circuit is live even though the car is in sleep mode. That circuit or relay when energized is pulling 0.3 amps.

3. According to the wiring diagram, the CAS module sends power to several circuits via the fuse box. The circuits are powered through a relay on the fuse box. This relay is also hot when the car is supposed to be in sleep. If I pull that relay the meter drops to 10mA. To summarize here... this relay powers several relays on the fuse block and one fuse is #28 which also contains a fan relay under the seat. So essentially two relays in series. Together that amperage draw adds up to what I'm seeing.

4. I can send a command from the Ista-d to send the car into sleep and the meter drops to 10mA (right where it's supposed to be). Both relays become deenergized.


Conclusion -

1. This leads me to believe either the CAS module is bad and not shutting down completely.

2. The CAS module is not shutting down because some other circuit is keeping it from shutting down.

3. I also confirmed via ista-d that no modules are becoming powered throughout the night. At least that's what ista-d says.



Can you test something for me?

1. Open the passenger door, manually move the latch on the passenger door to lock it. It clicks twice. Make sure you push it ALL the way in.

2. Open the glove box, tape the light button so the glove box light is off.

3. Remove the fuse box cover, Using your meter take a reading on fuse #28. While the fuse is plugged in. Record that.

4. Now lock the car. Immediately record the voltage again.

5. Wait 5 minutes and record voltage again on #28.

6. Wait an additional 20 minutes and record the voltage again.

7. When you recorded your last reading, remove fuse #28 and plug it in and out just enough to make contact. See if you can notice the cut off relay just under the front passenger seat clicking or not. If the line is in fact dead, you more than likely will hear nothing.


Can you post those results?

Thanks.

Doug

[Sensible_]

You seem to have a very good technical understanding of the issue.

Unfortunately I can't assist you right now. I've just sold my e90 and In the market for a replacement e91. If I pick one up in the next few days I'll run the test.

I never got to do an energy diagnosis with ISTA D. I know that with DIS you could look in a 'Sleep Mode Prevented' menu which indicated which module had prevented sleep mode. Does ISTA /D have this function?

By the sounds of it CAS seems a good bet.

[matteblue3er]

Pull fuses until the draw goes under 50ma. That's the current draw for E9x when the car is asleep.

Whichever fuse is related to the one you pulled that dropped current, is your issue.

[douglee25]

I am happy to report that I finally fixed this issue!

I thought by posting less detail I was doing everyone a favor (HA).

I've been trying to diagnose this problem for 1.5 weeks or so. I completing testing for excessive current draw by pulling fuses initially last week. That was the first thing I did to determine I had a problem... besides having a dead battery. I was wayyy past that step in diagnosing this problem. I found the current draw to be on the CAS circuit - fuse #36. I had reviewed a ton of electrical diagrams and I was trying to determine if someone else's car mirrored what mine was doing.

For what it's worth, the CAS module sends switched power to the Terminal 30g relay on the fuse block. This relay is one of the replaceable ones on the block. The terminal 30g relay powers about 15-20 circuits or so on the board. Between the actual Terminal 30g relay and the relay on fuse #28 (fan cut off relay), those both were responsible for my 0.5amp draw. Per all the documentation I read, the CAS sends the command to power down the terminal 30g relay in 30 mins or 60 mins if you have phone communications in your car.

I waited well past 30 mins previously and the meter was still showing 0.5amp draw. I also ran ISTA-D and it did not show any modules that were staying awake by becoming active after sleep was initiated with a lock sequence.... yet my power draw was 0.5amps.

I updated the software in the CAS. No difference. I was just about ready to take a bunch of readings last night with my meter but before I decided to do that, I reprogrammed the module (not software but the code) via NCSEXPERT. I ran the parasitic draw test with my meter in line, set my alarm for 32 mins just to give the system a few extra in case, came back to the car and what do you know.... 10mA draw! #BOOM! Turns out the code must have been corrupt in some way and recoding the CAS module fixed it.

All I can say is that problem would have cost me a ton at the dealership. I guess lesson learned here is to recode a module first before spending a ton of additional time on other things.

[Sensible_]

Interesting. Glad you fixed it. Did you backup the CAS before recoding? Would be good to have look through to try and identify the exact problem...

[douglee25]

I did not backup the CAS code.

Oh well. At this point I'm just happy it's fixed!

[ctuna]

If you lock the car is suppose to go to sleep.
Within a couple of minutes.
Mine does I can tell as light on my aftermarket amp
takes that long to go out when I lock it.

A lot of people have battery problems with these cars.
Other things that can cause them to stay awake is a
cell phone still in range or the keyfob to close.

http://www.google.com/url?sa=t&rct=j...,d.cGU&cad=rja

[douglee25]

It may 'look' like it goes to sleep right away, but it takes minimum 20 minutes I believe for ALL modules to shut down.

According to all the material I've read, the CAS doesn't initiate the switched power off command to the Terminal 30g relay for 30 mins or 60 mins if you have a phone system.

[serr]

Originally Posted by douglee25

I am happy to report that I finally fixed this issue!

I thought by posting less detail I was doing everyone a favor (HA).

I've been trying to diagnose this problem for 1.5 weeks or so. I completing testing for excessive current draw by pulling fuses initially last week. That was the first thing I did to determine I had a problem... besides having a dead battery. I was wayyy past that step in diagnosing this problem. I found the current draw to be on the CAS circuit - fuse #36. I had reviewed a ton of electrical diagrams and I was trying to determine if someone else's car mirrored what mine was doing.

For what it's worth, the CAS module sends switched power to the Terminal 30g relay on the fuse block. This relay is one of the replaceable ones on the block. The terminal 30g relay powers about 15-20 circuits or so on the board. Between the actual Terminal 30g relay and the relay on fuse #28 (fan cut off relay), those both were responsible for my 0.5amp draw. Per all the documentation I read, the CAS sends the command to power down the terminal 30g relay in 30 mins or 60 mins if you have phone communications in your car.

I waited well past 30 mins previously and the meter was still showing 0.5amp draw. I also ran ISTA-D and it did not show any modules that were staying awake by becoming active after sleep was initiated with a lock sequence.... yet my power draw was 0.5amps.

I updated the software in the CAS. No difference. I was just about ready to take a bunch of readings last night with my meter but before I decided to do that, I reprogrammed the module (not software but the code) via NCSEXPERT. I ran the parasitic draw test with my meter in line, set my alarm for 32 mins just to give the system a few extra in case, came back to the car and what do you know.... 10mA draw! #BOOM! Turns out the code must have been corrupt in some way and recoding the CAS module fixed it.

All I can say is that problem would have cost me a ton at the dealership. I guess lesson learned here is to recode a module first before spending a ton of additional time on other things.

Hi Doug,

Can you tell me how did you code the CAS module,just with a blank MAN file or did you looked at specific options in the module?

Im having the same issue like yours. I flashed but no luck.

[douglee25]

Sorry for the delayed response.

I used NCSEXPERT to reprogram the CAS module.

You have to load NCSEXPERT, connect to the car, open the CAS module, and reprogram it. My memory escapes me on exact details, but look up how to use NCSEXPERT and you should be able to figure it out. I would try to reprogram something simple first like coding out the door chime or something. If you can get that to work, you should be able to code the CAR module.

This may help as well. http://codinge90.com/ncs-expert-basic-understanding/

Just start googling 'coding with NSCEXPERT' and you should find a ton of info.

Let me know how you make out.

Doug

[serr]

Originally Posted by douglee25

I am happy to report that I finally fixed this issue!

I thought by posting less detail I was doing everyone a favor (HA).

I've been trying to diagnose this problem for 1.5 weeks or so. I completing testing for excessive current draw by pulling fuses initially last week. That was the first thing I did to determine I had a problem... besides having a dead battery. I was wayyy past that step in diagnosing this problem. I found the current draw to be on the CAS circuit - fuse #36. I had reviewed a ton of electrical diagrams and I was trying to determine if someone else's car mirrored what mine was doing.

For what it's worth, the CAS module sends switched power to the Terminal 30g relay on the fuse block. This relay is one of the replaceable ones on the block. The terminal 30g relay powers about 15-20 circuits or so on the board. Between the actual Terminal 30g relay and the relay on fuse #28 (fan cut off relay), those both were responsible for my 0.5amp draw. Per all the documentation I read, the CAS sends the command to power down the terminal 30g relay in 30 mins or 60 mins if you have phone communications in your car.

I waited well past 30 mins previously and the meter was still showing 0.5amp draw. I also ran ISTA-D and it did not show any modules that were staying awake by becoming active after sleep was initiated with a lock sequence.... yet my power draw was 0.5amps.

I updated the software in the CAS. No difference. I was just about ready to take a bunch of readings last night with my meter but before I decided to do that, I reprogrammed the module (not software but the code) via NCSEXPERT. I ran the parasitic draw test with my meter in line, set my alarm for 32 mins just to give the system a few extra in case, came back to the car and what do you know.... 10mA draw! #BOOM! Turns out the code must have been corrupt in some way and recoding the CAS module fixed it.

All I can say is that problem would have cost me a ton at the dealership. I guess lesson learned here is to recode a module first before spending a ton of additional time on other things.

How did you recode the Cas module with ncsexpert? ? Just write it to factory settings?

[douglee25]

Originally Posted by serr

How did you recode the Cas module with ncsexpert? ? Just write it to factory settings?

Correct. Just coding it to the factory program worked for me. You make any progress?

[Saliem24]

Hi Doug,

Im also having this problem where my battery goes completely dead after a night. Can you tell me how you performed the test to check which modules are awake using ista-d?

That would help me quite a bit!

[douglee25]

The details escape me slightly because it's been almost 3 years but from what I remember...

1. Disconnect the battery cable in the trunk and put an ammeter in between the battery terminal and the lug. I used small vice grips to clamp them there.

2. I taped (I believe that's what I did) all the trunk switches shut to simulate it being closed but left the trunk open and propped up the meter near the rear window so I could see it from the passenger seat. I couldn't figure out where/what simulated the doors being closed, so I sat in the car and waited until the car went to sleep (about 2-3 mins for the majority to shut down?) and the meter began dropping.

3. Once the meter stabilized, I started pulling fuses to isolate the exact circuit. It could have been something stupid like the radio, cell phone charger, etc. BMW's are apparently sensitive to this stuff, so just be aware. Make sure everything is unplugged that could alter results as well.

Of note - Apparently it can take 20-30 mins (I forget the exact number now) for the car to go fully to sleep. A couple of times I ran the test and just went inside for an hour and came back out to verify the draw on the meter was consistent. Then I did it again with the fuse pulled and verified my results.

4. Once you find the exact circuit I started looking at wiring diagrams to see what was on the circuit. In my case it should have been stuff that was either on or off - ie window motor. So it led me to believe it was the module on that circuit. That was essentially as far as I could take it. It was either replace the module with a used one, code it, and hope for the best or reprogram mine (which wasn't the ideal solution to do because you're utilizing the USB programming cable) and cross your fingers that it doesn't get bricked. I executed the reprogram and set up the meter again. Came outside an hour later and BAM! No more draw.


I'll be honest, this process was super tedious. Some of these electrical problems can take days to figure out. I think I spent several nights on it between actually doing the work on the car and researching online and reading wiring diagrams. Not fun!

Good luck!

[Saliem24]

Okay thank you!

Its a bit strange in my case because:

1. The problem doesn't seem consistent. I went on vacation last week and the car sat in the garage for a week. When i came home, i went to start the car and it magically started. I started driving the car daily again and the problem is back, every morning a dead battery.
2. When measuring the battery with the engine on, the battery is on 14.2v (charging state from what i have read, meaning the alternator works). But after driving the car, turning the engine off and turning the ignition on. The battery low warning comes on in like 5 minutes. (already replaced and coded battery with a new one so it isn't that)

Seems I have to keep trying to find the problem with pulling fuses then.

[gbalthrop]

Originally Posted by Saliem24

...I went on vacation last week and the car sat in the garage for a week. When i came home, i went to start the car and it magically started. I started driving the car daily again and the problem is back, every morning a dead battery. When measuring the battery with the engine on, the battery is on 14.2v ...meaning the alternator works. But after driving the car, turning the engine off and turning the ignition on. The battery low warning comes on in like 5 minutes...Seems I have to keep trying to find the problem with pulling fuses then.

BEFORE you start "pulling fuses," try disconnecting the alternator B+ terminal (large cable). Alternator diodes (or other components in the voltage regulator) can fail in such a way that even if it does produce voltage when the engine is running, it actually DRAWS current after shutdown.

So try disconnecting the Alternator B+ cable (AFTER disconnecting the battery negative cable so you don't short something), insulating the loose B+ cable at the alternator so it does NOT ground/short, then reconnect the battery negative cable and measure/record battery voltage (at least 30 minutes AFTER shutdown so that voltage has stabilized). See if it loses voltage overnight. If it does NOT for several nights of that procedure, but it DOES lose voltage again if you leave the alternator B+ cable connected, you have identified the problem.

A local shop, particularly one that rebuilds alternators can probably test the alternator to absolutely confirm if the test above is positive.

George,

[Saliem24]

Thanks for the info! Definitely going to look into this.

One question, if it is the alternator that is the problem. Would I have to replace the whole alternator or would changing the voltage regulator suffice?

In other words, are the components that can go wrong (diodes for example) in the voltage regulator or does the alternator itself also have components that can show this kind of behaviour when broken?

[douglee25]

Originally Posted by Saliem24

Okay thank you!

Its a bit strange in my case because:

1. The problem doesn't seem consistent. I went on vacation last week and the car sat in the garage for a week. When i came home, i went to start the car and it magically started. I started driving the car daily again and the problem is back, every morning a dead battery.
2. When measuring the battery with the engine on, the battery is on 14.2v (charging state from what i have read, meaning the alternator works). But after driving the car, turning the engine off and turning the ignition on. The battery low warning comes on in like 5 minutes. (already replaced and coded battery with a new one so it isn't that)

Seems I have to keep trying to find the problem with pulling fuses then.

Measure the voltage with a meter as well. It should be around 12.5-12.8 at rest. If it is, there's something else going on and likely isn't the battery.

[ride748@gmail.com]

Hi, I have a battery drain issue as well and found my drain can also be resolved by doing what doudlee25 did, that is pulling out the Terminal 30g relay. At this point id like to reprogram the CAS module. Did it reprogramming the CAS to factory settings work for you as well? Can you tell me what steps you took to reprogram the CAS to Factory settings with NCSexpert? Using NCSexpert is very confusing to me

[Dplaw]

Originally Posted by douglee25

I am happy to report that I finally fixed this issue!

I thought by posting less detail I was doing everyone a favor (HA).

I've been trying to diagnose this problem for 1.5 weeks or so. I completing testing for excessive current draw by pulling fuses initially last week. That was the first thing I did to determine I had a problem... besides having a dead battery. I was wayyy past that step in diagnosing this problem. I found the current draw to be on the CAS circuit - fuse #36. I had reviewed a ton of electrical diagrams and I was trying to determine if someone else's car mirrored what mine was doing.

For what it's worth, the CAS module sends switched power to the Terminal 30g relay on the fuse block. This relay is one of the replaceable ones on the block. The terminal 30g relay powers about 15-20 circuits or so on the board. Between the actual Terminal 30g relay and the relay on fuse #28 (fan cut off relay), those both were responsible for my 0.5amp draw. Per all the documentation I read, the CAS sends the command to power down the terminal 30g relay in 30 mins or 60 mins if you have phone communications in your car.

I waited well past 30 mins previously and the meter was still showing 0.5amp draw. I also ran ISTA-D and it did not show any modules that were staying awake by becoming active after sleep was initiated with a lock sequence.... yet my power draw was 0.5amps.

I updated the software in the CAS. No difference. I was just about ready to take a bunch of readings last night with my meter but before I decided to do that, I reprogrammed the module (not software but the code) via NCSEXPERT. I ran the parasitic draw test with my meter in line, set my alarm for 32 mins just to give the system a few extra in case, came back to the car and what do you know.... 10mA draw! #BOOM! Turns out the code must have been corrupt in some way and recoding the CAS module fixed it.

All I can say is that problem would have cost me a ton at the dealership. I guess lesson learned here is to recode a module first before spending a ton of additional time on other things.

https://ibb.co/DtzDvMP

I have the same problem!!! Mate please tell me what exactly do you coded in cas module? Or what you did in ncsexpert? I coded it with empty MAN. File nothing changes for me