Need help with electrical gremlin. Non BMW car

[peelsbimmer]

The car is a 99 gs300. When ever I hit the breaks, turn on a/c, move the seats, use turn singles or anything that uses any sort of power. All my lights flicker, radio cuts off and the car acts like it wants to die. These problems have started about two hours after a good bass note, from a new installed sub. So I double check all the wires, all was good. Had the battery tested, it was only showing 40%. So I replaced the battery and alt with new parts. That seemed to work for about 3 days. So I just completely took out the entire sub setup and pulled the fuse for the amp wire. Now, the problem seems to getting worse. Whenever I am at idle, all my dash back lite lights flicker like crazy, idle bouncing all over the place. Ever now and then my VCS, ABS light will come on, but, I replaced the unit last year with a known working one. Could I be having ECU problems? I don't have any check engine lights that come on.

Is anyone here good with electrical problems? Or know someone that is? This is the wife's car, so I would like to get this fix before she wants to trade it in.

[jaydee99]

Hello. I myself am a bmw owner for the first time a 2002 x5 so I am not what you would call an expert. However in my experience as a HD mechanic when you have this kind of global electrical problem it almost always is a ground problem somewhere. Look for a loose or corroded ground wire to the engine or to the chassis. Less often it can also be a B+ wire maybe at the starter or connection to a fuse panel. Hopefully this helps. Cheers

[EisnerRacing]

make sure the harness from under the dash - going thru the fire wall has not come loose - this happened in an old ford ranger i had same thing - lights and gauges acting funny and stalling

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also double check the power cable that runs from the battery to the fuse box under the hood. it should connect with a 10mm nut - it may be loose or need cleaning

[peelsbimmer]

Hello. I myself am a bmw owner for the first time a 2002 x5 so I am not what you would call an expert. However in my experience as a HD mechanic when you have this kind of global electrical problem it almost always is a ground problem somewhere. Look for a loose or corroded ground wire to the engine or to the chassis. Less often it can also be a B+ wire maybe at the starter or connection to a fuse panel. Hopefully this helps. Cheers

I've replaced the ground wire from the battery to the chassis. I've double check every single ground wire I could think of. The car starts perfectly fine, but I'll check the starter again.
Awesome first post.


make sure the harness from under the dash - going thru the fire wall has not come loose - this happened in an old ford ranger i had same thing - lights and gauges acting funny and stalling

- - - Updated - - -

also double check the power cable that runs from the battery to the fuse box under the hood. it should connect with a 10mm nut - it may be loose or need cleaning

I'll check the power cable. I was going to replace it today, but, no shop around here had it in stock.

[Hatch]

Sounds like your alternator is failing or you need to upgrade the AMPRE output.

My first car was a Mazda MX-6. When the alternator would start failing, if I used any kind of electical draw, blinker, radio, etc. the car would act all crazy; jerking from when the blinker would flash on and off.

[peelsbimmer]

Alt is brand new. Less than four months old.

[Joey30]

Alt is brand new. Less than four months old.

Is it really brand new or was it a reman from the parts store?

[peelsbimmer]

reman. i guess I could pull it off and have it check. Just for safe measure.

[peelsbimmer]

Just had the alt check, said it was good. Starter volt was 10.99. Load and no load of the charging system was 12.46v

[vollosso]

Sounds like an alternator voltage regulator to me. Based on first few posts. Remember even new parts are sometimes bad.

[carlova789]

Fuse maybe?

[jakksfor20]

My mom had a similar issue in her '95 Mustang. Car would just shut off even at speed or act like it wanted to every once in a while. Ended up being the ECU.

[328iJunkie]

Engine ground?