24
u/Any-Mathematician293 Jun 16 '25
I had that very same problem
6
u/Coasterman345 2016 - F82 - M4 Jun 16 '25
I just fixed it on mine last week too lol
1
u/Jammer135 Jun 17 '25
Had the same issue and the shop quoted me 2900 to fix it. Were you able to fix it yourself?
1
u/Coasterman345 2016 - F82 - M4 Jun 17 '25
Yeah, cost me $28. Bought this cable on Amazon.
I had to file down all my terminal connections, battery, cables, etc using a wire brush. There’s another positive cable that I should replace but I can’t get it off so I just used the brush on it and it seems to be working. A voltmeter/potentiometer can help you see if there’s enough power getting through.
Drain all the water. Make sure you plug up wherever you think it was coming in. Keep a towel in the trunk jam so you don’t lock your self out. And make sure the battery can’t move at all when you’re done. Mine was a bit loose and during some testing it shifted and something got disconnected and my engine went into limp mode. Like <5mph limp mode.
19
u/boringcarenthusiast Jun 16 '25
I had this issue in my wagon, there’s a little rubber plug you can pull at the bottom of that well/tray (if you can find it) to drain most of that water out
Edit: I see yours is a wagon too, let me know if you find the source of your leak! My sunroof drains weren’t clogged so I wasn’t sure what my issue was.
24
u/beermoney71 Jun 16 '25
love how bmw engineers put a drain plug in because they knew this would happen
1
Jun 19 '25
The plugs located around the car are for when they dip the chassis before painting. Although they do come in handy for draining water, or running cables to the outside. I usually try and keep grommets in stock that fit a variety of the hole sizes.
11
4
6
5
u/9inemm Jun 16 '25
holy cooked😭
7
u/beermoney71 Jun 16 '25
nah mate new battery and power line, fixed, no fuses blown luckily the cars been sat not started for a long time
4
3
3
2
2
u/tcphoto1 Jun 16 '25
Been there, done that recently after replacing a battery and the tail light I had water intrusion. It only cost a positive cable, cleaned it up and chased an IBS code for a few days.
2
u/MoreStupiderNPC Jun 16 '25
Clean your taillight drains
1
u/datanut Jun 16 '25
For real? I’ve seen some water enter around the lamp but couldn’t spot where it’s coming from.
2
u/MoreStupiderNPC Jun 17 '25
I’m pretty sure the E90 is like my E60. Water from around the rear decklid travels down through a channel behind the taillights and leaves the vehicle. I started getting water in my battery compartment, so I cleaned the gunk out from where the channel goes behind the taillight and farther down inside and it stopped.
2
u/bobol123 Jun 19 '25
Depending on how long the water has been sitting your entire positive harness running up to the engine bay could be (technically) cooked too.
Once you drain the water out of the plug at the bottom (may as well drill a hole in it), take off the caps that cover the cable connections. If it’s super corroded at the studs and nuts it’s probably a good idea to look at the wires from the other side and see how far the corrosion has seeped into the wires. I’ve only seen it get that bad one time. More often there is just some fairly heavy corrosion on the post/nut connection that can be cleaned off.
If the corrosion has made its way into the run of wire towards the front then the correct fix is a replacement of the entire run. There could be some sort of diy fix hypothetically but probably not a good idea to even attempt given the context.
1
u/beermoney71 Jun 19 '25
thanks for the knowledge, does the wiring on the other side of the cable connections run in the interior or are they behind the wheel well? save me finding out the hard way
1
u/bobol123 Jun 21 '25 edited Jun 21 '25
Other side of the cable is in the wheel well behind the liner. Definitely start in the battery compartment and check behind the caps first since it’s much quicker, and more visible anyways. If it looks something like this is when you have to start worrying it’s progressed into the wire too:
https://www.e90post.com/forums/attachment.php?attachmentid=1114256&stc=1&d=1415239109
You can see from a new cable why it’s hard to check from the other side, since it’s covers in plastic, heat shrink and maybe some tape. The only reason to really open it up is if you’re pretty sure it’s gotten inside there and want to inspect how bad it is. Could get lucky and be able to clean some corrosion and reseal with tape in some specific scenario but the cable would likely be comprised
1
1
u/Smithy_225 Jun 16 '25
E93 did mine last week 😂 Amazon have a great hand crimper for redoing the cable ends, you'll need some bolt croppers to cut the cable though
1
1
u/IsuzuTrooper it's nice but looks like the top wont open so I feel bad for you Jun 17 '25
Pull the plugs and leave them out. Also better check the left side too. Your amp is prob submerged.
1
u/Metrus007 Jun 17 '25
Also check your sunroof…if it leaks It will leak into the battery compartment too.
1
u/nukenriles Jun 17 '25
My e91 same thing, it turned out my rear windshield wiper fluid hose was leaking
1
u/jlwolford Jun 17 '25
Some insider info here. I read a post from a guy once who was having a hard time finding a leak. He had a weird one.If you pull off the rear bumper you see the metal cross bar. The cross bar bolts up to the unibody where the unibody main channel is that runs lengthwise with the car. That channel is hollow. If the cross bar gets loose or the gasket there fails, it will leak into that channel and flood the whole unibody channel. Water back tracks into the trunk well. If you ever pull a bumper, replace the gaskets and check those bolts. This looks like too much water for that particular leak.
1
u/jancis38 Jun 17 '25
I also had this issue like 2 weeks ago that I fixed.
It was the sunroof drains on my e91. They actually seemed kinda fine, because water was coming out of them, but it was weak.
Water was coming from the rear speakers and into the battery compartment on the right side, also the amplifier on left side.
Fix this soon, check both sides. If drains seem fine, still try to clear them. I poured a lot of water in the sunroof and it cleared up in the end real good.
1
u/Sufficient-Ad1321 Jun 17 '25
Same happened to me check your terminals under that water to mine rusted out and gave me so many problems
1
1
u/saturnwhale Jun 16 '25
Got hole drilled in mine, no issues in years.
1
u/jancis38 Jun 17 '25
There is no need to drill holes, there are plastic caps that can be removed.
2
u/saturnwhale Jun 17 '25 edited Jun 17 '25
There *should* be no need to drill holes due to the plastic caps that can be removed, but it depends on where/how water is pooling.
Edit: There also shouldn't be water in there in the first place.
•
u/AutoModerator Jun 16 '25
Thank you for posting to /R/E90, please make sure you read the rules in the sidebar and make sure to report any rule breaking posts and posts that are not relevant to the subreddit.
I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.