Random electrical issue limits power

[BrockWed]

I know trans. failsafe prog. has been covered quite extensively in this forum but my problem is a little different. I got a sub installed and whenever I'm listening to it loud for a long period of time (what I think may be the problem) my dice unit plays music then stops then plays then stops, then my 4x4 light goes on, and then trans. failsafe prog. lights up the dash limiting my power to almost nothing. I always pull over turn off the car and wait, sometimes it wont start right away and act like my battery is completly dead. If I wait another 5 or so minutes my car starts and runs perfectly. I'm going to take it in next week but I was wondering if anyone had an idea of what could be the problem

[e30mpower]

Yeah. Ran into this problem a few days ago, but in a completely different way. In my case I needed a new alternator, I was on my way to the shop to get it tested when I almost died in the road. Your amp is drawing more power than your charging system can supply. A symphony of warning lights will come on when you hit that low point and random electronics and computers will begin to shut themselves down to save power in an effort to keep the engine running. In my case, it was DSC and ABS, then I got Trans. Failsafe Program, then I got the airbag light, and then my engine started sputtering. Turn down the volume man.

[Weasel]

How big a sub/amp setup you running? You may need to freshen up the battery/alternator and install a power capacitor for the amp if not done so already. Sounds like the sound is draining the voltage down too much and that is causing your problems.

[BrockWed]

e30mpower, I have the exact same symptoms as you, i really hope its not an alternator. was that pretty pricey? Weasel, its not a super powerful system, i have the stock premium sound and then a 12'' JL W3 with amp to spec. Capacity could be a good idea but its not like a trunk raddeling W7

[e30mpower]

All my electrical problems started when I tried to use the hidden power outlet under the dash. I have the stock audio and everything. Not sure what caused my alternator to fail like that. But anyways at the indy shop I use, the part was $550 and some change and my total bill came to $740, but they also replaced the drive belt. I guess I'll have to put Inspection II off for another few thousand miles. Hendrick BMW quoted me like $850-900. If you're going to insist on continuing to run that amp you're absolutely going to need a higher power alternator, the stock one is either 90 or 120amp.

PS.. I do have to say that I really appreciate how the BMW is smart enough to turn off electronic modules in order of decreasing significance, it wasn't until my airbag light came on that I started to look for a place to ditch though.

[NOVAX5]

You guys should be careful with those electronics stuff. It WILL kill the battery and the alternator. I would never mess with BMW electronics. My experience proved it. After I changed a HID light bulb to a aftermarket (higher wattage). The darn things killed my battery, alternator altogether. Left my wife stranded on I-95. I replaced the stock bulbs. No problems ever since. With the aftermarket high wattage bulb, the darn battery lights danced to the music. Flickered like crazy to the music. Dont mess up with BMW electronics if you don't know what you are doing.

[Weasel]

I am currently using an infinity reference 8" in a BSW bow run on a directed D800 mono amp (300 watt RMS @ 4 ohms) with a level remote knob up front. I have not had any problems, even with short trip driving.

How do you have the power, ground and remote run? I have my power to an extra 80 amp fuse n the rear power distribution box, ground to the main battery chassis ground, and remote to the OEM amp's remote turn on.

[BrockWed]

I have no idea what I have run to be honest, I had it professionally installed at circuit city. I think parts costed like 120 and 80 for install so whatever that got me. haha.

[Weasel]

I don't think I would call Circuit City "professional"... I mean sure, they'd do fine on lets say like a chevy tahoe. But odds are they have the power cable run from the little nut on top the positive terminal, better hope they didn't just run a sheet metal screw into the chassis for ground.... and the remote turn on is likely jumped to either the wrong wire or to constant power.

Most install shops don't know nearly enough about the delicate and picky electronics of modern BMWs. You could take pictures of the install (mainly where the other ends of the wires to the amp go) and I could tell you if that is your problem or if they did good.

[BrockWed]

I'll take some pictures tomorrow and hopefully you could tell me if its hooked up properly