Fuse 1 Battery Draw

[Ericks2002]

I was trying to diagnose an issue with the blower motor so while I had the multimeter out I decided to check my current draw because the other day the car died after sitting for a few days.

I hooked up the voltmeter in series with the left battery in the trunk and disconnected the right like Tims website says and I was getting a 2 amp draw! I Traced the draw to fuse 1 and once I pulled it the car dropped to a hair above 500mah and then after 16 minutes went to 150mah in sleep mode. I know 150 is high but I was going to chase down the extra 100mah once I fix the 2 amp current draw

When I install fuse 1 back in the draw is gone until I start the car again. After the car has been started and shut off the current draw is back to 2amps until I pull the fuse again.

I saw fuse one operates:

Immobiliser
Park Ventilation
Instrument Cluster
IHKA (A/C unit)
Wiper Relays
Aux Water Pump
Start
EML


There’s so many things hooked up to fuse 1 I’m not sure how I would go about checked which is the cause. Any help would be appreciated.

[shogun]

I from guts feeling would first check the IHKA control unit. It has on each side 2 plugs. Pull one after the other and check with the multimeter.
IHKA and sword pinout I posted here http://www.bimmerboard.com/forums/posts/1248867/

if that is o.k., start with the easier to remove ones, aux water pump can be easily disconnected = 1 plug, wiper relay can be removed, cluster can be removed.....

[Timm]

Yes, I agree with Erich - check if the water valves are warm to the touch after leaving the car an hour or so - that would indicate an IHKA problem.

[Ericks2002]

I’m thinking it’s the ihka module too because I rebuilt the sword and I’m still having blower issues I also feel like after 15 minutes of driving it gets hot in the cabin even tho I’m not running the air and the controls are all maxed to the cold side.

[Ericks2002]

You guys were on the money. I checked the water valves with the car locked and they were warm. I unplugged the valve and you could hear them click and the amp draw dropped from 2.5 a to 1 A when the car is locked and not in sleep mode. My thought Then was that ihka was operating other things so I unplugged the sword first and nothing change. Then I unplugged the ihka and now my draw when the car is locked is at 450mah and when the car is in sleep mode 45mah.

I saw you can repair the ihka and also found a used unit for $150. Wasn’t sure what the best plan an of action would be.

[Ericks2002]

I talked to Omega Man today thinking he could rebuild my IHKA but he said to check the General Module. I was reading and it sounds like ihka is powered by the ignition switch and not the GM. Not sure if that could be my problem but im going to take it out and check anyways.


I opened up my IHKA to look and see if it had any bad solder joints or resistors but for the most part it looked in good shape other than being burnt like everyone else. I re soldered the 120 ohm resistors anyways but im still having the same issue.

Another piece of information i discovered today when testing IHKA. It seems like IHKA is remembering what the climate control was on when the key is turned off regarding the heater valves. If I turn the key off and the climate is in heat the solenoids will stay in that position and the same goes for when I turn the key off when it is on full cold. I confirmed this by listening for the solenoid to click off when I turn the ignition off and the CC is on cool or I listen for it to turn the solenoid on when I turn the ignition on with the CC on cool. This is also confirmed because when I check voltage drop across fuse 1 I am getting about 23 mV when I turn the key off with it on Cool (Heater Valves Activated to stop coolant flow) and 10mV when I turn the key off while its on heat (heater valves deactivated). I get the same drop from 23mV to 10mV when I unplug the HV while it is activated and I can hear the solenoids clicking off.

What seems to be happening is IHKA is remembering or getting power somehow to remember what the climate control was on when the key is turned off. The blower motor on the other hand does not stay running if I take the key out. I also removed relay K4 but it didnt have any change on the voltage drop across fuse 1. I narrowed down the Battery draw to the white plug on IHKA. Not sure if that means anything but when I unplug the white plug the current draw at the battery drops from 2.5 A to 500mah when the car is locked and then to 50mah when the car is in sleep mode. Also sometimes when I plug IHKA back in the problem doesn't immediately come back. It may take a few ignition cycles to come back.

Hopefully this makes sense. Just trying to confirm what the issue is before I purchase a new (used) IHKA.

-

[Timm]

If removing Fuse 21 sees the current draw drop then the problem is elsewhere, if it makes no difference then the IHKA is the problem

[Ericks2002]

Okay thanks I will give that a try

[Ericks2002]

Got a chance to look at the current draw this morning. I plugged ihka back in and now the blower works on all speeds ( this is the first time in about a week). Still have a current draw when the doors are locked though. Removed fuse 21 and still saw a 23mV voltage drop across fuse 1 and also ran the current draw test like you have on your website Timm and I had ~2.5A current draw when the car is locked which didn’t change at all when I removed fuse 21.

I was curious if anyone thought those L475D chips inside IHKA that control the heater valves could be my issue? If not It sounds like I just need to buy a new IHKA.

[Ericks2002]

Completely lost at this point.

Got a "new" IHKA module and the issue is exactly the same. Intermittent blower motor operation and heater valves staying on when car is locked.

I was under the impression that the IHKA was powered solely by the ignition switch. So I have no idea how the heater valve could be staying on while the car is locked with a new IHKA module.

It almost seems like there is another module which is powering IHKA because when I pull fuse 1 the current draw goes away and does not come back until I cycle the climate control a few times by turning the ignition on and off.

Any help at this point would be greatly appreciated. I am stumped.

[Ericks2002]

Found a thread about battery draw linked to module A15 for park ventilation. https://www.bimmerforums.com/forum/s...in-issue/page2

I went being the glove box and unplugged it and my issue seems to be gone.

[Ericks2002]

Started the car this morning after it sitting for a couple days and it felt like the batteries didnt have very much charge. I checked fuse 1 again and it had 25mv voltage drop with the car locked. This time when i unplugged the fuse and plugged it back in i could hear relays clicking on and off. I narrowed them down to the 3 wiper relays. They were hot and would click on and off when fuse 1 was removed and reinstalled. I saw these are controlled by the A5 module. Is it possible this was the cause of my battery draw all along?

I am skeptical mostly because the draw seemed to go away when i unplugged the ihka module and then when I unplugged the park ventilation module. Does this module have any control of those modules? Or could this have been the issue all along and the other modules stopping the battery draw were a coincidence

[cartoonz]

Started the car this morning after it sitting for a couple days and it felt like the batteries didnt have very much charge. I checked fuse 1 again and it had 25mv voltage drop with the car locked. This time when i unplugged the fuse and plugged it back in i could hear relays clicking on and off. I narrowed them down to the 3 wiper relays. They were hot and would click on and off when fuse 1 was removed and reinstalled. I saw these are controlled by the A5 module. Is it possible this was the cause of my battery draw all along?

I am skeptical mostly because the draw seemed to go away when i unplugged the ihka module and then when I unplugged the park ventilation module. Does this module have any control of those modules? Or could this have been the issue all along and the other modules stopping the battery draw were a coincidence

you wipers are not parking properly.

[Ericks2002]

My wipers seem to operate and park just fine. How can I tell if they are not parking correctly?

[cartoonz]

My wipers seem to operate and park just fine. How can I tell if they are not parking correctly?

Why else would those relays go nuts when the fuse were replaced? Unparked wipers cause the General module to not "go to sleep", hence your large current draw and inability to keep batteries fresh for very long when car sits.

I suppose there could be something funny going on with the relays themselves, but that should be easily checked.

Bottom line, I think you found the answer to your original question.

[Ericks2002]

My thought was I have an issue with the A5 Relay module because that module controls those 3 wiper relays and other functions.

https://www.bimmerforums.com/forum/s...-Bench-Testing

according to this thread operating the wiper stalk or moving them does not cause the car to wake up. I’m not sure how my wipers couldn’t be parking properly because they move up an inch Or so when operated and stay above the cowl until they are turned off which then they drop about an inch to the parked position. I have also left my wipers halfway wiping before to remove the plastic panel under them to work on the intake and valve cover gaskets for couple days and did not have any battery draw issues.

I talked about it earlier in this post but my car seems to go to sleep fine even when it has the current draw because it drops from 5 amps when locked to 500 mah when sleeping. Of course this is way out of spec but it still seems to sleep after 15 minutes and not wake up. Also I don’t think the wiper relays are the sole cause of the battery draw because the heater valve was also staying on when the car was locked. I am not sure if the A5 module controls the the heater valve though.

[Ericks2002]

So far the wiper relays haven’t stayed on anymore so that seemed to be a fluke. The original issue of the heater valve staying on is still happening. The park ventilation module is unplugged and the “new” IHKA module is in the car. Is there a timer that keeps the heater valves on after the key is out and the car is locked or should they shut off immediately? At this point I’m starting to think I have an issue with the ignition switch because I looked at the schematic and the heater valves are controlled only by the ihka which is only controlled by the ignition switch. Any help would be appreciated.

im basically back at square one at this point because it’s doing the exact same thing it was doing before I unplugged the park ventilation module and replaced the ihka with another unit.

[Timm]

The IHKA is continually powered via F21 (Hot At All Times) - that's why we discussed it a while ago

[Ericks2002]

I saw people with the park ventilation issue saying relay k4 was staying on and powering their valves. I checked relay k4 and it is not staying on.

consistently the battery draw comes on when I drive the car somewhere and then goes away when I pull fuse 1 out which I can hear the heater valves clicking offI. I keep looking through the schematics and the only thing powering the heater valves is the ihka.

I swapped back to my old ihka and the problem still persists. I’m wondering if it’s possible I received and ihka with the same issue as mine but I find that very unlikely.

Is it possible something else is powering ihka allowing it to power the heater valves. I know you said fuse 21 is always hot but there doesn’t seem to be current running through fuse 21 when measuring the voltage drop. Fuse 1 is the only fuse with a voltage drop. I also remember when I unplugged the connectors to ihka the heater valves would shut off which makes me think something is powering ihka.


I was reading that bmw e46s keep the heater valves closed and powered for 3 minutes after the car is shut off. I haven’t read anything about the e31 doing the same but I thought I would ask if our cars have a similar feature

i was also wondering if there would be a way to check if the HVAC control panel is the issue.

[Ericks2002]

Cartoonz was right. The wipers are causing a battery draw. I had the same issue the other day where the 3 relays were staying on and keeping the car from sleeping and I cycled the wipers once and the draw went away. I also found another 100mah draw on the steering column module so I pulled the fuse for that for now.

My wipers have the common problem of hitting the cowl. If I fix that would that fix my wiper park problem? Other than that I’m not sure how else to get the wipers to park properly all the time.


Also I think I was right about ihka controlling the heater valves and other things after the car is turned off. I’ve tested it about 3 times and every time after I drive and shut the car off there’s a 22mv voltage drop across fuse one and a couple minutes later it will go away. This is how I found the wiper issues I was getting a 26mv voltage drop and it only went down to 3.5 after a few minutes so I knew something else was staying on and it was the wiper relays of course.

[cartoonz]

Cartoonz was right...

Of course he was, that arrogant bastard! haha

If the wipers are being physically restrained by the hood/cowl, try raising the center hood bumper up slightly.
Also, check for play/binding in the wiper shaft bushings themselves.

[Ericks2002]

Appreciate the help. I never would have guessed haha.

For now I ordered new wiper bushings so I will report back once those have been installed.

[EEDegreeToDrive]

Cartoonz was right. The wipers are causing a battery draw. I had the same issue the other day where the 3 relays were staying on and keeping the car from sleeping and I cycled the wipers once and the draw went away. I also found another 100mah draw on the steering column module so I pulled the fuse for that for now.

Glad you narrowed it down!
Just to add to this, and a reminder to my GM discovery post referenced earlier. Removing the wiper relays will keep the car awake.
It's just a reminder that simply yanking fuses and relays until the current drops could have unexpected consequences, particularly as many modules and systems in the car have multiple power sources and all bets are off for 'normal' operation if you are only providing partial power (or running without certain relays)

Also, I'm not entirely sure of this, but in my wife's 2008 Jetta, the wiper control will 'park' the wipers on alternating edges of the blades, to preserve the blades. Perhaps our 90s BMWs are doing the same!?. Regardless, I maintain that it's probably a software bug that wipers that fail to park (or a car with missing/damaged relays) can cause a problem with the car sleeping, perhaps from someone trying to implement a similar feature?