Odd electrical noise from rear undercarriage
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Driver School Candidate
Joined: May 2013
Posts: 14
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From: PA
Odd electrical noise from rear undercarriage
I took something out of my trunk tonight, closed it, and a few minutes later heard a noise in my garage that I couldn't locate at first. Hard to describe but it sounded kind of like a small motor humming. It was fairly loud and I thought it was maybe an AC adapter going bad in my garage but after some listening around, it's definitely coming from the car. It was loudest directly under the trunk, between the exhaust pipes. I could hear it from inside the trunk, but it was much louder under the car. I got it to stop by turning on the ACC power and then turning it off.
The car was shut off for 5 hours and the noise wasn't there until a few minutes after I closed the trunk. Whatever it is, it's obviously something that's being powered by the battery, but the trunk was fully closed, car was off and the key was inside. I posted a thread about my battery dying after 600 miles and now wonder if whatever was happening tonight also drained the battery that time.
Anyone else experience this? There's a noise from the engine compartment when I shut off the car that stops after about 20 seconds. This is different, definitely coming from the rear end somewhere. I'm hoping I don't go out to another dead battery tomorrow, especially with it being garaged in the winter.
The car was shut off for 5 hours and the noise wasn't there until a few minutes after I closed the trunk. Whatever it is, it's obviously something that's being powered by the battery, but the trunk was fully closed, car was off and the key was inside. I posted a thread about my battery dying after 600 miles and now wonder if whatever was happening tonight also drained the battery that time.
Anyone else experience this? There's a noise from the engine compartment when I shut off the car that stops after about 20 seconds. This is different, definitely coming from the rear end somewhere. I'm hoping I don't go out to another dead battery tomorrow, especially with it being garaged in the winter.
Lexus Test Driver
Joined: Aug 2003
Posts: 897
Likes: 11
From: colorado
I took something out of my trunk tonight, closed it, and a few minutes later heard a noise in my garage that I couldn't locate at first. Hard to describe but it sounded kind of like a small motor humming. It was fairly loud and I thought it was maybe an AC adapter going bad in my garage but after some listening around, it's definitely coming from the car. It was loudest directly under the trunk, between the exhaust pipes. I could hear it from inside the trunk, but it was much louder under the car. I got it to stop by turning on the ACC power and then turning it off.
The car was shut off for 5 hours and the noise wasn't there until a few minutes after I closed the trunk. Whatever it is, it's obviously something that's being powered by the battery, but the trunk was fully closed, car was off and the key was inside. I posted a thread about my battery dying after 600 miles and now wonder if whatever was happening tonight also drained the battery that time.
Anyone else experience this? There's a noise from the engine compartment when I shut off the car that stops after about 20 seconds. This is different, definitely coming from the rear end somewhere. I'm hoping I don't go out to another dead battery tomorrow, especially with it being garaged in the winter.
The car was shut off for 5 hours and the noise wasn't there until a few minutes after I closed the trunk. Whatever it is, it's obviously something that's being powered by the battery, but the trunk was fully closed, car was off and the key was inside. I posted a thread about my battery dying after 600 miles and now wonder if whatever was happening tonight also drained the battery that time.
Anyone else experience this? There's a noise from the engine compartment when I shut off the car that stops after about 20 seconds. This is different, definitely coming from the rear end somewhere. I'm hoping I don't go out to another dead battery tomorrow, especially with it being garaged in the winter.
i have a super charger on my tacoma that has the air to water intercooler. it apparently is hooked into the fuel pump circuit because when the tacoma does it the pump for the intercooler runs also.
i don't think it does this all the time, its either timed from the last time the engine was running, or senses something in the fuel system that turns it on.
either way its totally normal. i recall reading about this in the owners manual for the truck after i heard it the first time years ago.
What you're hearing is the EVAP system doing its self-check. It usually does it 4-8 hours after the car is turned off. My wife's Sienna does it as well, pretty loud in the garage if youre not expecting it. Has nothing to do with the fuel pump.. just a vacuum pump and a bunch of solenoids doing their thing...
Lexus Test Driver
Joined: Aug 2003
Posts: 897
Likes: 11
From: colorado
What you're hearing is the EVAP system doing its self-check. It usually does it 4-8 hours after the car is turned off. My wife's Sienna does it as well, pretty loud in the garage if youre not expecting it. Has nothing to do with the fuel pump.. just a vacuum pump and a bunch of solenoids doing their thing...
I'm sure it's tied to an ignition circuit, only needs to be on while engine is running.
Rookie
Joined: Feb 2013
Posts: 50
Likes: 0
From: Missouri
The first time I heard it, I heard it on my 07 Camry... I thought something was wrong and searched profusely for an explanation as to why it was doing that. It turns out it in fact was the evaporative system that does it 5 hours after the car is turned off, as Bass said... My 2010 Camry did it, my 2013 Camry does it and my partners 2013 ES350 does it. Nothing to worry about! 
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