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Humming from rear of car?


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First off I would like to say that I am the proud second owner of a 2001 deville base model with 89k miles. The car is in great condition and the carfax stated it had never been in an accident and had been regulary dealer serviced. I have had it about a week and absolutely love the car!!

I have noticed a low humming noice coming from the rear of the car several times. Is this a noicy fuel pump or do these cars have some sort of load-leveling rear suspension?

I dont know anything about these cars and was just curious about this. Any comments would be appreciated!

2001 Deville, Sterling Silver exterior with Dark Gray leather, 93k miles

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Go to the top of this page, click How To, then DTC codes, then follow the directions for your year, retrieve the codes if any and post them here

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Depends on when you hear the noise.

Yes, there is an air bladder on the rear shocks that serves as a load leveling mechanism. The suspension module runs a test on the load leveling system at every KEY ON event. Depending on how long the car has been sitting, you will hear the compressor run for a short period approximately 20 to 30 seconds after KEY ON.

The compressor is located in the RR fender well.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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Yes, they all have ELC (Electronic Level Control). Sounds like you are hearing the ELC pump. Usually you only hear it at start up or if you load the trunk. If you are hearing it regularly, I would suspect a leak in one of the lines.

EDIT:

Oops. Jim beat me to it.

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Congratulations on your new car and :welcomesmiley: to the board.

In answer to your questions...your car DOES have an automatic load leveling system.

If the sound you hear is only occasional and intermittent...it is probably the auto load leveling system and nothing to worry about...unless it does it a lot.

If it is more a constant noise...it may be a noisy fuel pump.

If you suspect it may be the fuel pump...open the fuel filler door...remove the gas cap and have someone turn on the key while you listen at the open tank.

Don't forget to put the gas cap back on. :D

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It is probably the ELC pump I'm hearing then, because the humming seems to be coming from the RR of the car. I have noticed it at startup and a couple of times while sitting in the car before turning the ignition off. It's not running constantly, and I've only noticed it a few times. But I'll roll around underneath it and check the lines and bladders for any signs of damage or wear.

Just as a note, I do have an extra full size wheel and tire in the trunk for a spare, so there is added weight in the trunk from that, not sure if it would make a difference but thought I would mention it anway. I may remove it and see if it still occurs.

Also, if there was a leak in the lines or bladders wouldn't the rear end sag after the car had been sitting for a while? Just a thought...

Thanks

2001 Deville, Sterling Silver exterior with Dark Gray leather, 93k miles

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I checked the codes as described in the "how to" section and it retrieved no codes. I also inspected the hoses and suspension parts that I could see from underneath for damage or wear and everything appeared to be in good order.

I have an appointment saturday to have a 4-wheel alignment done on the car and will ask them to further inspect the suspension.

I dont thinks its a problem, and had planned on taking it in for an alignment anyway.

Thanks

2001 Deville, Sterling Silver exterior with Dark Gray leather, 93k miles

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Got the car back from the alignment shop. They checked out the ELC components and everything was fine.

I guess I tend to be a little to paranoid sometimes. Sure am glad there was nothing wrong.

2001 Deville, Sterling Silver exterior with Dark Gray leather, 93k miles

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Got the car back from the alignment shop. They checked out the ELC components and everything was fine.

I guess I tend to be a little to paranoid sometimes. Sure am glad there was nothing wrong.

Thats good to hear...that there is nothing wrong. :D

Thats always good news.

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