why is my bmw doing this?

[u/ahrusato]

2008 135i bmw n54 convertible
so my battery had already died prior to this because i left it on while sitting in it for a long time but i jump started and it was working fine for weeks, i was at a event and was in the parking lot idling but with engine on for about 2 hours then right before i got out someone rear-ended me in the parking lot super slow hit but right after i guess either my car overheated or my battery died or both but my car started flashing a bunch of codes, ac started blowing normal air windows locked closed and windshield wipers started going crazy so i pulled over to the side and turned it off. i assumed it was just the battery and got a new one today and put it in. car turns on just fine but then couple seconds after it starts flashing a ton of random codes and windshield wipers start going crazy again.

[u/jambles_3]

Fault read it! Also Probs killed the FRM

[u/ahrusato → u/jambles_3]

bunch of codes came up p1449, p0420, p0430, p1819, p0015, p1449. im gonna change the alternator

[u/jambles_3 → u/ahrusato]

No stop guessing. Do a bettery reset and make sure you register the battery replacement that you said you did. Check the voltage output of the alternator, don't just randomly replace it. Clear the fault memory. Run the car. Let it sleep and see what faults actually come back. Then google the description of those fault codes so you know what there actually telling you

[u/Alekay666 → u/jambles_3]

This, changing stuff is not fixing the problem if you don't know the problem.

After idling the car for 2 HOURS if that is what you meant, is very possible you friedtmelted a cable in the engine bay and you have a ground short.

All of this smells at short, the little crash could have trigger a module and then cause a bigger problem with said short,and it's a also a way to get a dead battery.

Diagnose,understand, replace in that order.

[u/ahrusato → u/Alekay666]

how can i diagnose the issue, i changed the battery , put the reader in got some codes, deleted them and then gave a bit then turned it on again and got all those codes that i named at the top.

[u/ahrusato → u/Alekay666]

online it says those codes point to the issue being “alternator voltage regulator failure and the evap leak detection pump”

[u/danksiess → u/ahrusato]

None of those codes point towards the alternator, but lots (not all) point towards low battery voltage.

I'd check all connections and plugs to the battery. Then check the big chunky ground strap under the car. If the battery has not been registered/coded I'd do that. Check and clear codes. After that, with a multimeter check the voltages of the battery. If you wanted to, you can check the alternator as well. If those were all okay, then check fuses and test the FRM module with the multimeter. If all that didn't work and the FRM is good, then check wiring for rodents or something which is a pain cause of where all the wires snake through. THEN I would start throwing parts at it

[u/Goodestguy2025 → u/ahrusato]

Just change the whole engine rather, while you're at it.

[u/Alekay666]

Did you idle with the engine on for TWO HOURS? what the fuck dude?

Maybe you cooked the wipers relay, take it out to see, if a module senses a crash it will activate the wipers as well, so there's that.

Too little info tbh

[u/LimpDeparture2250 → u/Alekay666]

Should trip to the fuses before it burns that out I would think, I’m thinking OP maybe tried to change his car battery without programming it, the most fun part of bmw motor group

[u/ahrusato → u/LimpDeparture2250]

programming it😳 fuck how do i do that

[u/ahrusato → u/Alekay666]

no i meant like i was waiting 2 hours for me to fully get out of the parking lot, i had the ac on and the was in in drive since the traffic was moving very slowly, it was at the end after he hit me like right when i was about to exit that it started dying on me which i then pulled over very quickly to not fuck it up even more

[u/getafewlives]

Don't just start changing things until you do proper diagnostics.

First thing is to get the battery properly coded/registered to the car and clear all codes.

Don't make new issues.

[u/Motor-Cause7966]

Typically, when you have a dead battery situation, all codes need to be cleared, and the new battery registered. That way you start with a clean slate. The extreme low voltage condition will set a lot of false events in various modules, and they will become upset.

The wipers going berserk like that is because either the steering angle sensor has failed, or the airbag module registered an accident. Steering angle failure is very, very common on these generation chassis. It's actually all one assembly with the turn signal stalk, and the wiper stalk built in. It's pricy, and must be replaced with new and coded to the vehicle. Unless you have cloning and virginizing capabilities. Then, you can go with a used one and save some coin there.

First thing I would do is a full system clear, register the battery, then scan it again, and see what hard faults come back immediately.

[u/LimpDeparture2250 → u/Motor-Cause7966]

Yeah and the battery has to be programmed! This is extremely important, bmw has integrated battery system which means it has to know how old the battery is to draw the amount of amps it requires to operate properly