PDA

View Full Version : Electrical Gremlins



ryankokesh
10-09-2013, 06:59 PM
My biggest fear has become a reality... I have an electrical problem. :help

First symptom was the stereo kicking off for ~2 seconds. The sub stayed on though, so it must have been the amp cutting out. (sub's pre-amp) This happened about once a day at first, then with increasing frequency. Next I noticed that when I started the car in the morning or evening after sitting all day, the tach wouldn't move smoothly as the car started. It would kind of sit there and then spring up at the last minute. I also have my radar detecter set to display the voltage when it isn't detecting, and I started to notice wild fluctuations. So I took the car to the local auto parts chain and had the battery and alternator tested. Both passed with flying colors.

So with that, I came to my own conclusion that it had to be the voltage regulator. I Amazon Primed one over and stuck that in. The voltage fluctuations improved quite a bit, and the stereo issues dramatically decreased. They didn't stop though, and starting the car was still wonky. (Note that after the car had been running for a while, starting it again was totally fine.) After driving for a while the voltage on the detector would get up to around 13.3 volts.

Finally tonight I dug out my multimeter and took readings across everything I could find.

At battery off: 12.36v
At battery on: 14.00v
Front posts off: 12.32v
Front posts on: 14.05v
Alt to ground off: 12.34v
Alt to ground on: 14.19v
Cig lighter on: 12.8v
Cig lighter off: 11.94v

And now I'm totally and hopelessly stuck. Alt seems to be working fine, and battery seems like it's also fine. I also did really poorly on the electrical sections of my high school physics classes, so I have very little idea of what I'm doing. :blink

:scratchinghead

ryankokesh
10-10-2013, 03:36 AM
Is it abnormal to not see the ~14 volts across the lighter outlet in the car?


Sent from my iPhone

ryankokesh
10-10-2013, 03:27 PM
C'mon... ya'll are the best e46 folks around! Someone's gotta have an idea! :)

My current guess: battery was messed up by irregular charging due to the previous bad voltage regulator. That's such a shot in the dark it's not even funny, though.

kayger12
10-10-2013, 03:42 PM
I like where your head is at. How old is the battery?

That's where I would start.

I believe the 12v at the lighter is normal.

Sent from my SCH-I535 using Tapatalk 4

ryankokesh
10-10-2013, 03:45 PM
Imma dumbass. Secondary positive cable off the batter was ever so slightly loose. Helped to replace voltage regulator because I disconnected the battery.

:facepalm


Sent from my iPhone

kayger12
10-10-2013, 03:49 PM
Lol. Good solve. Always good when you figure it out before you spend money!

Sent from my SCH-I535 using Tapatalk 4

ryankokesh
10-10-2013, 03:57 PM
Ha ha yeah, I guess I'm set on voltage regulators for a while. :thumbsup


Sent from my iPhone

Avetiso
10-10-2013, 04:23 PM
Sometimes, when no-one helps, it forces you to recheck your basics. Happened to me multiple times.

Glad it worked out.

Sent from my SPH-L720 using Tapatalk 2

ELCID86
10-10-2013, 04:49 PM
Glad you solved it (and that's all it cost you!).

ryankokesh
10-10-2013, 04:51 PM
Hah, thanks guys.

Important Note:
If you have a Bosch alternator without the air duct, a voltage regulator from an 03 Z4 3.0 WILL fit, even though no parts stores say it will. It's also only $50 on amazon shipped!


Sent from my iPhone

johnrando
10-10-2013, 05:13 PM
Glad it worked out. Secondary positive cable?

ryankokesh
10-10-2013, 05:20 PM
The little one on top of the thicker one... I dunno what it's there for...

http://i.imgur.com/mBEXoYW.png


Sent from my iPhone

johnrando
10-10-2013, 05:22 PM
Thanks for the response. Was just looking that up... thought that might be it. Not really something that would be loose I would guess so glad you found it.

ryankokesh
10-10-2013, 05:24 PM
Yeah, I accidentally bumped it when I was taking another voltage reading and the lights kind of flickered. So totally not an intentional fix!

Anybody know why there's two of them?

Sent from my iPhone

Hornung418
10-10-2013, 05:34 PM
the tiny one is the BST or Battery Safety Terminal. In the event of a crash, a small charge explodes and severs the line. This will keep the car from being restarted should you attempt to.

ryankokesh
10-10-2013, 05:36 PM
I NEVER would have guessed that.


Sent from my iPhone

Fried_Chicken
10-15-2013, 12:02 AM
the tiny one is the BST or Battery Safety Terminal. In the event of a crash, a small charge explodes and severs the line. This will keep the car from being restarted should you attempt to.

You have got to be kidding me.

I was always impressed by the little things, but this takes the cake.
I would imagine it also has something to do with the car not causing a short circuit after an accident.