[dylanAr10]

So I just recently fried and replaced a mosfet on my DME (the one for injector 5) well after getting the battery charged and (Died of course) & replacing the coil pack all seems to be running well as far as the motor is concerned. However for whatever the reason my POS car has decided I no longer deserve heat nor do I deserve a driver side window that tucks when opening & closing (Oddly enough it is only the driver side the passenger side still tucks in....) never the less I drove the car over to a friends to see if the engine is 100% and it was however the battery died again (Had a full charge and the battery came back as still having 675CCA) But with minimal use of the interior lighting it died again. Well I got a jump and still same issues with the heat & driver window. So I checked the fuse for the blower (67 According to the lovely schematic BMW provides) which appears fine. So since I had my cowl off already when I replaced the coil pack I checked the blower motor from the air vent under the hood to see if it was seized however it moved freely. Moreover when I turn the fan on and off I hear some sort of engaging noise. Any help is appreciated.

[Socket]

Originally Posted by dylanAr10

So I just recently fried and replaced a mosfet on my DME (the one for injector 5) well after getting the battery charged and (Died of course) & replacing the coil pack all seems to be running well as far as the motor is concerned. However for whatever the reason my POS car has decided I no longer deserve heat nor do I deserve a driver side window that tucks when opening & closing (Oddly enough it is only the driver side the passenger side still tucks in....) never the less I drove the car over to a friends to see if the engine is 100% and it was however the battery died again (Had a full charge and the battery came back as still having 675CCA) But with minimal use of the interior lighting it died again. Well I got a jump and still same issues with the heat & driver window. So I checked the fuse for the blower (67 According to the lovely schematic BMW provides) which appears fine. So since I had my cowl off already when I replaced the coil pack I checked the blower motor from the air vent under the hood to see if it was seized however it moved freely. Moreover when I turn the fan on and off I hear some sort of engaging noise. Any help is appreciated.

A dying battery can cause all sorts of weird electrical problems and codes
Replace the battery with a new one and see if everything plays nice again

[Underground6t9]

If you have a dying battery then you have an electrical short somewhere, mine was dying after a few hours of the car being off. It turns out that the rear defroster would stay on while the car was off draing the battery. I disconnect the fuse and all is well.

[dylanAr10]

Well rested the battery today, no issues thing is still storing 720cca. Also to note the entire heating system is dead not just the blower aspect. Rear Defroster also not working. So anyone have any ideas? I've checked the associated fuses from the glove box but they are all solid. I will say the issue with the driver side window not going down was fixed simply by driving around lol. One thought I had is the electronics have adaptions don't they? Much alike throttle and transmission adaptions, that modulate power based on degradation of received voltages and what not.

[terryd5150]

Has the battery cable been replaced? Or has the car been in any sort of accident (even a fender bender w/o airbag deployment)?

There was a service bulletin on them a few years ago. One of mine was fixed under warranty.

They show multitudes of electrical gremlins if that cable goes bad.

[dylanAr10]

No, accidents. My only guess is the little fuse on the DME just below the mosfet for cylinder 5 probably has something to do with the heater and probably died when I replaced the mosfet.

[dylanAr10]

Update: figured out the issue! Underground6t was in part right (the battery drain part)

Originally Posted by Underground6t9

If you have a dying battery then you have an electrical short somewhere, mine was dying after a few hours of the car being off. It turns out that the rear defroster would stay on while the car was off draing the battery. I disconnect the fuse and all is well.

The battery only died randomly once but this explains why. So after much research to no end I pulled the blower and was about to go out and buy another. While examining the blower I noticed something odd about the final stage resistor, two of the pins were burnt to hell! So instead I ordered a new resistor unit I figured since I had the cowl off for some time when I was waiting on the mosfets for my DME maybe water had got on two pins and caused a short that fried it. Well while reinstalling I found some sparky little wires with very little shrouding on them, found my short thanks everyone if anyone has this issue in the future hopefully this helps!

Also anyone facing this very specific issue be warned the spark I saw looked quite powerful (similar to the 120V arcs you see from a wall outlet)

[muncie21]

Thanks for sharing that!

[dylanAr10]

Turns out this specific part was just recalled lol.