Inside Cabin High Pitched Whine

[Smallville]

2008 MS3 GT

I've only owned this car for a couple weeks and I'm slowly fixing the previous owner's neglect. On today's menu is a high pitched whine that I hear inside the cabin. It's coming from somewhere in the backseats (I want to say the rear passenger seat area) and it faintly dies down in volume when I use the power window switches.

Not sure if this is related but I also have a battery drain issue that I'm also chasing down. The previous owner installed an aftermarket headunit and wired it for subwoofers. I'm going to take it to a car audio shop to see if they wired it correctly but just wanted to see if anyone knew whether this whine is normal or not.

[Bingo]

Something making a whine = something foreign being powered or some component in the car dying. It dies down when windows are used = it is drawing some current at least with ACC on. No this is not normal. If you don't know how the sub is wired, I would suggest taking out its wiring and starting from there.

[Natey]

Turn up the stereo and rev the engine. Is it louder with the volume up? If so check the grounding for the audio system, especially if it's aftermarket.

[Djohns]

Is there a baby in the back seat? Possibly your wife/girlfriend if equipped?

[PapaBruno]

Maybe previous owner had a sub and amp? I'd check under the seats for and foreign or out-of-place looking wiring.

Sent from my SAMSUNG-SM-G900A using Tapatalk

[Smallville]

Originally Posted by PapaBruno Maybe previous owner had a sub and amp? I'd check under the seats for and foreign or out-of-place looking wiring. Sent from my SAMSUNG-SM-G900A using Tapatalk

Someone shoot me now...

[PapaBruno]

Originally Posted by Smallville Someone shoot me now...

Hopefully that's the source of your whining issue.

Sent from my SAMSUNG-SM-G900A using Tapatalk

[JSmith]

https://www.youtube.com/watch?v=STNrDw8qpag

[Smallville]

Originally Posted by JSmith https://www.youtube.com/watch?v=STNrDw8qpag

I think I'd rather deal with that than my car's whine....I think.

[Djohns]

That shouldn't be too bad of a fix though! Just rip those wires out and be done with it.

[GroceryGtr]

If that was part of his wiring that you CAN see I don't even want to know about the shit thats hidden. I strongly advise ripping EVERYTHING out and doing it correctly. Those are household connectors, hell it would be an upgrade if you just twisted them together and used electrical tape. Id be seriously concerned about electrical damage to other components and/or a fire from that hack job. The resistance has got to be incredible.

$60 and a few hours and you'll solve all your problems. Not to mention the piece of mind its done correctly(and safely).

[MSMS3]

If the whine is electric/electronic in source, consider isolating the circuit by experimenting with removing fuses to accessories and the window motors, one at a time.

When you pull the fuse on the responsible circuit, the whine will stop. Then you can figure out what component needs to be either removed or replaced.

[Smallville]

Update: I've located the draw to a 40A BTN fuse in fuse box under the hood. This fuse protects the headlights, interior lights, hazard lights, turn signals, and who knows what else. I have yet to go through all the fuses in glovebox compartment to try and isolate the circuit further.

I feel stupid for not saying this earlier but in addition to this whine and my battery drain, my power locks don't work. After replacing the rear door lock actuators I think the whine is gone but I still have a battery drain. Reading another forum I think it's related to a bad CANbus on the aftermarket radio. Supposedly all I have to do is switch the constant and accessory wires on the CANbus and the drain should go away. I'll update when I try all this during the weekend.

[5doorsoffury]

Originally Posted by Smallville I think it's related to a bad CANbus on the aftermarket radio. Supposedly all I have to do is switch the constant and accessory wires on the CANbus and the drain should go away.

Ummmm what? Ok so first of all.... what?

Second wth are you talking about switching constant and acc on the can bus?

So what i think is the source of your wine is from the subs. So lets say he does a shitty job of installing the subs with no Low pass filter. The wine will come from a bad AMP, Ground or running rca's close to power cables. Unless he has a 4 channel aftermarket amp i doubt they are coming from your speakers. He could of tapped power or more likely the remote wire off of a circuit on that 40 amp fuse of yours.

Now onto the can bus. It is data plain and simple. You cant keep something on unless you are commanding it to stay on. Second a MS3 shouldn't have any canbus interface for the sterio....... So even if the radio could command something to stay on which it isn't the radio would stay on with the ignition off.

I would rip EVERYTHING aftermarket out of the car. Then start from the smallest fuse and work backwards. Then start unplugging shit that is not yellow loomed until the draw goes away.

You said you have a draw but you didnt say how much or how you were detecting it. Some one asked if the wineing got louder when you raised the volume and you never answered him. Turn the radio all the way down then rev the motor with your head next to each speaker and see if the wine changes with rpm. Did he run a power cable to the battery?

[Jonb82]

Make CANbus great again


Sent while probably pooping

Build a wall around the subs


Sent while probably pooping

[Smallville]

I'm happy to report that everything has been resolved. Below are the 3 issues and fixes that I was dealing with.

Problem #1 - All four door locks weren't working properly. The rear driver's side would unlock when pressing the power switch but wouldn't lock, and the other three wouldn't move at all. To fix this I had to replace all four door lock actuators. Apparently these actuators are a common problem but to have all four go out is kinda crazy.

Problem #2 - Battery drain issue. Connecting an amp meter in series with the negative battery cable/clamp showed a draw of 240mA even after letting the car sit for 30 minutes. After fixing my door lock actuators the draw dropped to 150mA (I suspect an actuator was either stuck open or preventing the car from going to sleep). Another mazda forum told me that the Eonon GA5151 headunit the previous owner installed was sold with a faulty CANbus decoder. All I had to do was switch the constant power and accessory power wires from the CANbus and now I'm reading a draw of 20mA (after waiting 30 minutes for the electronics to time out).

Problem #3 - Electronic whine coming from the backseat that would die down in sound when using the power windows. Listening carefully it was coming from right in the middle of the backseats. According to my mechanic it's the fuel pump and it's normal. I only heard it because I took my backseats out when tracking my battery drain issue. Once I put the backseats in again the noise was masked.

I can FINALLY enjoy my car. Thanks to everyone who chimed in!