ECU buzz/high pitch noise

N0tn2jd · 03-16-2009, 10:27 PM

My friend let me try his JB3 today. When removing the big connector I heard this buzz/high pitch noise emitting from the ECU. Is this normal? I did unplug the battery.

krnshinsa · 03-16-2009, 10:29 PM

shouldnt be hearing anything since the battery was off

hotrod182 · 03-16-2009, 10:38 PM

While the battery was disconnected? Haunted car!

GAaaAR · 03-16-2009, 11:51 PM

You're car got excited.

Ilma · 03-17-2009, 12:47 AM

I believe I read somewhere, that even with the battery disconnected, energy is still stored in the capacitors and can take a while to fully dissipate even after the battery is disconnected.

A good tip is to fully drain any stored power after disconnecting the battery by running the emergency flashers.

laperacfo · 03-19-2009, 01:35 PM

will anything happen if you hear the sound? weird though. battery was disconnected.

03-16-2009, 10:27 PM	#1
N0tn2jd Registered 0 Rep 3 Posts Drives: 09 335i sedan Join Date: Mar 2009 Location: NJ iTrader: (0)	ECU buzz/high pitch noise My friend let me try his JB3 today. When removing the big connector I heard this buzz/high pitch noise emitting from the ECU. Is this normal? I did unplug the battery.
	Appreciate 0 Tweet Quote

03-16-2009, 10:29 PM	#2
krnshinsa Captain 81 Rep 606 Posts Drives: e92 335i Join Date: Dec 2007 Location: el ay iTrader: (2)	shouldnt be hearing anything since the battery was off
	Appreciate 0 Quote

03-16-2009, 10:38 PM	#3
hotrod182 . 829 Rep 3,982 Posts Drives: 2023 i4 M50 Join Date: Dec 2006 Location: California iTrader: (0)	While the battery was disconnected? Haunted car! __________________ 2011 Alpine 335d M-Sport 12.34 @ 110.48mph 2019 i3s Terra, 2008 Black 335i Sedan. 11.11@ 129.47 mph 2008 Monaco Blue JB3 2.0 335i Coupe. 11.33 @ 132.77 mph, 60-130mph: 6.95 seconds 2023 i4 M50 11.48 @ 121.56mph, 3.43 0-60 (dragy)
	Appreciate 0 Quote

03-16-2009, 11:51 PM	#4
GAaaAR Captain 33 Rep 671 Posts Drives: 2009 E92 335i Join Date: May 2006 Location: NYC iTrader: (1)	You're car got excited.
	Appreciate 0 Quote

03-17-2009, 12:47 AM	#5
Ilma Colonel 185 Rep 2,842 Posts Drives: 2008 135i Join Date: Nov 2008 Location: Mississauga iTrader: (0)	I believe I read somewhere, that even with the battery disconnected, energy is still stored in the capacitors and can take a while to fully dissipate even after the battery is disconnected. A good tip is to fully drain any stored power after disconnecting the battery by running the emergency flashers.
	Appreciate 0 Quote

03-19-2009, 01:35 PM	#6
laperacfo First Lieutenant 48 Rep 372 Posts Drives: BMW Join Date: Jun 2006 Location: NY iTrader: (0) Garage List 2012 X5 [0.00]	will anything happen if you hear the sound? weird though. battery was disconnected.
	Appreciate 0 Quote