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18k CPS from right rear

3K views 17 replies 7 participants last post by  BigBlue 
#1 ·
I have a 06 Commander and lately I started hearing a high pitched whine from what sounds like the right rear (up high) on accelaration only. I have no idea what is up there, and the whine sounds like it is from the radio ( sounds electronic) but I still hear it when the radio is turned off. After driving for about 40 minutes it disappears.

Has anybody else encountered this? I went weeks thinking it was Tinitus and my old ears, but my young son confirmed the existence.

On a side note, is the Commander still in production?

KKKKFL
 
#3 ·
The pitch is so high that it is difficult to ascertain the exact location.. but my best guess is that it is coming from behind an interior panel just ahead of the right rear wheel. It is only under acceleration and disappears when I lift off the gas pedal.

Surely someone know what electronics are located in this area? How about a fuel pump?

KKKKFL
 
#4 ·
No longer in production 2006–2010.
As for the high pitched noise. Not sure what it could be exactly. Up high on the right rear I think there is only HVAC controller for the 3rd row seating. Hmmmm wonder if it has something to do with the coolant that it circulated back there. Other than that maybe the fuel pump? Might want to have someone else drive while you try to pinpoint the location.
 
#5 ·
What happens if you rev it in neutral (or in gear with the brakes on)? Reverse? Change with speed (what speeds)? Can it be heard outside the vehicle?
 
#6 ·
I tried reving it in neutral, and there was no sound. I only hear it under load conditions. As I cruise down the interstate, any lift off the pedal and the sound disappears. It also goes away after 20 minutes of interstate driving. It may have something to do with the outside temprature. Since I only hear it under a load condition, I couldn't tell you if the sound can be heard outside the vehicle. The pitch doesn't really change with a variation in speed, but the same pitch is a little louder if the load is increased (ie. going up a greater incline).

Thanks
KKKKFL
 
#8 ·
Do you know if the windshield has been replaced recently? Mine made a a high pitch sound and they ended up replacing thw glass. This happen from new and was a common problem. Not sure how long you have had yours. My XK is an 06 Limited. 4.7
 
#9 ·
Almost sounds like the transmission based on the fact that it stops when not under load try using the manual shift (if you have it) and see if happens in multiple gears.
 
#10 ·
Due to the location, (Right rear, either behind the panel or under the right rear seat) its doubtful that this is transmission related. I have had windshield issues in the past when the front windscreen was replaced, so I know what that sounds like. This is more of an "Electronic Squeal" Very high pitched. It does go away after 20 ot 30 minutes of driving. It is very similar to the ringing (Tinitus) folks have in their ears. I may have to put someone in the rear with a Stethascope to try and locate it.

KKKKFL
 
#11 ·
It still makes the same noise with the third row seat heating on or off? If it is coming from the interior behind the panel I believe there is only the HVAC housing under there. But the housing is a complete heating/AC unit with all the necessary bits to operate / possibly malfunction to create you "Electronic Squeal" sound. Removal of the Remove right rear quarter panel trim would be helpful to pinpoint the issue.

Rear heating/AC unit parts:
Heater core
A/C expansion valve
A/C evaporator
Temperature control blend door actuators
Blower motor
Rear blower motor resistor
 
#12 ·
I didn't think to change the rear heating settings... I cannot make any connections as to why HVAC would be impacted by engine load, but I'll give it a whirl by changing some of the settings that are in the rear and report back if it makes any differences.

The sound is almost certainly coming from the right rear in or around the seat or panel.

KKKKFL
 
#13 ·
You are right, it is odd about the sound not being there when just reving the engine without load. Usually any electrical/coolant sounds change with reving of the engine with or without load but if the sound is coming from behind the rear trim there isn't much left :)
 
#15 ·
I had a bearing go on our old minivan but it got progressively louder with speed and was independent of the load from the engine. That is why I thought transmission instead of the bearings. It could possibly be that the sound is more pronounced and noticeable when the rpm and sound from the engine go down which could take it back to the bearing. It is a weird one. Good luck. I am definitely not a mechanic and don't even play one on TV and didn't stay at a Holiday Inn Express.
 
#16 ·
I tried turning on the rear heater unit, but it didn't make any difference. A couple other points. This is a very High pitched whine like what you would hear from a High Voltage transformer. It only kicks in when the RPM of the motor reaches 1800 and is under a load. When I did start up the rear AC unit, with the blower going, it helped in that the sound is coming from somewhere in front of the rear blower but it is definitely on that side.

KKKKFL
 
#18 ·
Here's an update...
Early this morning (5:00 AM) I started off to work with the High pitched squeel as I drove up the street. Lately, I have been trying to get the Air pressure the same in all tires, and the right rear was showing 2 pounds over the others. I pulled over and in those early morning hours, when all is still and quiet, and with the motor off, I bent down to pop the stem cap. With my ear just in front of the rear wheel, I could hear some lower frequency sound coming from just in front of the rear wheel but near the bottom of the Jeep.

I'm wondering if it is related to my other problem, but don't have any idea as to what is located just in front of that wheel.

Any ideas?


KKKKFL
 
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