BMW Newbie - battery draw in fuse 98
 

My X5 doesn't start in the morning with fuse #98 left in overnight. Sorry if this next bit is overexplained, but I'm new to this whole forum thing. Still figuring it out.

Last week I bought my first BMW: 2010 X5 (E70) xDrive35d with just under 90k miles. This is my first used car I've owned as an adult, and I have virtually no experience with car repairs, nor any interest in writing my local mechanic into my nonexistent will.

The dealer replaced the battery after the mechanic that checked it out pulled these codes:
3EED | Power Management Closed Circuit Current Violation
4A56 | Power Management Battery
4661 | Power Supply
4121 | Engine ECU Main Relay

Supposedly the new battery would fix everything (did I get swindled there?) so I bought it.

Parked overnight in my garage, it would be dead every morning (totally dead, needing 15+ minutes hooked up to jumper cables to charge). After delving into the DIY auto repair world for the first time (thanks guys, good to be here), I guessed I was dealing with parasitic draw, and proceeded to test the voltage drop across each fuse in the fuse box.
While there (with the car off/sleeping) the rear A/C fan started blowing...actually (after further investigation) sucking--like a terrible vacuum with hardly any suction. The car was still 'asleep' with no lights anywhere (shifter, start/stop button, doors, etc.). I rechecked the fuses and #98 was passing ~13v, whereas it was at 0v before the fan turned on. *bingo* = my battery draw, right?

So I've pulled fuse #98 and the rear fan no longer works (as expected). Everything else seems to work fine, so I'm planning on leaving it out until I can do so without killing my battery overnight.

But that begs the question: why is the blower turning on randomly while the car is asleep? And further: why does it spin in reverse, creating suction instead of blowing?
So far I've witnessed the phenomenon twice: once about 5 minutes after sleep, and another time about 25 minutes after sleep. Both times the fan sounded like it was at full blast, making the center console vibrate, but not blowing any air and generating a tiny bit of suction.
A few times, after I'd connect the jumper cables and charge the battery a bit, the blower would turn on along with a few other lights (e.g. the shifter, start/stop button, etc.), but I thought it was just normal after a dead battery--maybe not so.

Closest thing I can find is a possible bad rear blower motor, but there's not enough detail here to be sure. Especially since mine is starting up while the car is OFF, not while driving. Additionally, the rear climate control works great when the car is running.

Any help to diagnose this would be much appreciated. Assuming the battery doesn't die again tonight, my next step would be to order a new blower motor on eBay and DIY install it, then re-insert fuse #98 and take a nap in the back seat hoping not to be woken up by a rude fan.

In case anyone else is experiencing something similar, here are the key resources I've used:
E70 Battery Access: https://www.youtube.com/watch?v=bE22LoDpIQE&t
How to test with multimeter: https://www.youtube.com/watch?v=COJr7OB23Hw
E70 Fuse Box Access: https://www.youtube.com/watch?v=6TcGl_YJYps
Best way to test for parasitic draw: https://www.youtube.com/watch?v=lRcj1fQcWwU&t
E70 Fuse Box layout key: https://fusesdiagram.com/bmw/fuses-a...mw-x5-e70.html

BMW Newbie - battery draw in fuse 98
 

Blower controller aka FSU also FSR is the most common parasitic draw.

Final Stage Unit aka Final Stage Resistor

I don't know why BMW decided to have them stay powered with key off other than on some models you can use the "rest" function to blow heat with engine off and key out.

My X came with a replaced FSU at 128k miles. Wife's died about 115-120,000 (we got at 112, was the first repair).

There is a separate FSU for the back seat. I haven't had to replace either of our back seat FSU.

We have e53 I don't know how similar the FSU arrangement is on the e70 but I'd be willing to bet "nearly identical".

Search YouTube for e70 rear FSU replacement. (aka FSR even though it hasn't been an "R" for 30 years or something;).

Some old habits die hard: perfect example, my father's generation refers to residential AC power as 110/220 vs. 120/240 and it has never been that in my lifetime though in 3 phase shop AC 220v is cross phase power so that is possibly where the 220 came from.

Anyhow one of my first posts to co was to figure out the parasitic draw killing wife's battery overnight and it was the front FSU hedge hog. I bought a knock off brand from Amazon and it's still going after 191,000 current miles so lasted about 70-75,000 not bad.

I will use knock off parts in non mission critical places where they are also easy to replace. On e53 it's a five minute job with no tools to swap out the front FSU.

The rear I understand is more work because of the location inside the console.

As far as how when sleeping: either the FSU gets power when sleeping or it's random power draw prevents sleep I'm not sure which.

Almost zero percent chance it's not FSU.

Thanks a ton! And good to hear that the FSU is cheaper than the motor.

Sounds like the FSU goes out due to the climate control fan being on low most of the time--lots of FSU resistance with little air flow to cool it down. Still very strange to me that it was sucking in...

Based on what I'm (not) finding online, the rear FSU is a much rarer issue. No video tutorials or even blog posts, while the main/front FSU is comparatively common, even on Xoutpost. There is a compatible rear FSU part on eBay, however, so between that and the fact that the front blower works with fuse #98 out, there's gotta be a way to get in the center console and replace it....I just haven't found it online. I'll have to give it a few more weeks until I have a free Saturday.

If there's anything I've learned this week, it's that BMW has more acronyms than the US Army.

I've read more about the IBS (intelligent battery sensor), and it sounds like that should be kicking in to turn off the FSU before it drains the battery too much to start the car. Am I understanding wrong? If so, does that mean my IBS is bad? I checked the battery and there aren't any unattached cables, so I doubt it's been removed without my knowledge.

Misnomer about the low speed. It's not like ol school resistor pack where all the power not used on the motor drops on the resistor. If I had to bet I would say it's PWM but clearly not that efficient if it needs all the "quills" in the direct airflow for cooling.

Heat kills so you are still likely correct in the why do they die but our FSU lasted 15 years or so and you can't really complain about that.

Confirm it works or not.

The problem with the IBS saving the day is that it would just signal the FSU off which it already is. I don't think there is any way to power down the FSU

I've still got #98 pulled, but unfortunately the car hasn't stopped dying, it just takes much longer to do so. With #98 in it would die within 12 hours, now it seems like it lasts around 24 hours, and still has enough juice to turn on, just not turn over more than once (it's very cold here, and it's a diesel, so maybe it's the glow plugs that suck the last bit of juice out).

It seems to me like there's a secondary culprit. Nothing on the rear fuse box seems to be the issue, but the fuse box in the passenger dash is too recessed to have gotten my multimeter probes in there. I'm going to try and find out whether it can be removed fully to have better access, so I can test those fuses for positive voltage drops while the car is off/sleeping (like I did the rear fuses earlier). I thought the IBS was supposed to keep this from happening? Or if the FSU is circumventing the IBS, could something else be doing the same thing?

However, I'm wondering at this point if the computer knows exactly what's going on (ie. where the draw is, assuming there's only one more), and it would be better to just buy a OBDII cord/bluetooth reader and see what it's saying? I was wanting to get into coding down the road, so perhaps I need to go find out what one product could provide both diagnostics and coding function. I'm sure there are plenty of threads on that.

The worst news is that I believe I may have fried the FRM jumping it this morning, as now I've got all the classic symptoms including the "Lighting failure!" error. However, the car also shifts from R or D into P as soon as I take my foot off the brake, so it's stuck out in my driveway. Maybe that's an issue for a totally different thread?

I'm about to go order an FRM repair for $60 on eBay, since I'd prefer that to the $1k some people are mentioning dealers charge. Found a helpful video to easily remove it. While I'm waiting for that I'm planning on hunting down the second battery draw, but also wondering if the draw could have been the FRM itself, and if I should test that before sending it off for repairs. Thoughts?

I'm getting the feeling I need to find a trustworthy BMW expert somewhere close by. Anyone have personal recommendations for mechanics in Utah?

BMW Newbie - battery draw in fuse 98
 

FSU definitely bypasses any attempt of battery management. If you haven't ruled out FSU definitely unplug that sucker

You can't reality do DIY on BMW without a proper scan tool. The cheap painful route is the free software and old crap top The far less painful way is foxwell 510/520 scanner you can often get on eBay half price

You're still referring to that rear FSU, right? I've already pulled that fuse long ago to eliminate that draw. Or are you referring to the main/front FSU as well?

Could the FRM have been causing the draw, and now it's shorted out for the same reason, so repairing it will solve both problems? Too good to be true?

I'm seeing the Foxwell NT510/520/530 for $134/158/159 respectively on eBay. Do you not recommend the NT530? None of these will code anything, so I guess I'll look into BimmerCode down the road, rather than trying to get a package deal. That might be the most user-friendly option anyway.

I've seen weird things about the 530 and yes the front FSU is 90% or more the cause is parasitic drain. Pull the fuse or actual hedgehog

Quick question....perhaps 2


1. Are you doing all this troubleshooting without schematics?


2. If yes, WHY?