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Forgive me if this had been discussed before. I searched and didn’t find a thread. If there is one, please post the link.
When I’m driving, there is a motor that’s constantly whirring near/under the passenger seat. I assume that it’s the motor to inflate the bolsters in the seat, which are probably all burst by now.
Is this what I’m likely hearing? What’s the best way to disable this motor? Fuse, unplug?
You sure it's not the blower motor under the glove box area? Those are notorious for making squealing noises and just generally being a PITA. A little off topic but that problem is easily remedied by cramming wheel bearing grease in the LOWER fan bearing. It's absolutely not necessary to replace the blower assembly or remove it for greasing. It's the bottom bearing that causes all that racket. Back on topic though...
If no one is sitting in the passenger seat, none of the dynamic functions should be active on that seat IIRC. Not entirely sure on that though.
You can unplug the air pump fairly easily to help narrow down the problem. The pump is in the driver side (US models) trunk area, sandwiched between the rear quarter panel and trunk carpeting/liner. Remove the trunk floor liner from the car, remove the foam tray piece directly behind the back seat, pop out the plastic rivets on the trim piece that runs from the trunk latch to either side of the trunk closest to the bumper, then remove the driver side trunk liner panel (few pop out rivets, light fixture, and the 12v socket. Doesn't have to come all the way out. You'll see a black/gray box covered with gray foam insulation directly forward of the rear taillight assembly/behind the DVD drive and fuse panel. Just unplug the wiring connector. It won't cause any warning lights or anything.
You sure it's not the blower motor under the glove box area? Those are notorious for making squealing noises and just generally being a PITA. A little off topic but that problem is easily remedied by cramming wheel bearing grease in the LOWER fan bearing. It's absolutely not necessary to replace the blower assembly or remove it for greasing. It's the bottom bearing that causes all that racket.
Well, I hadn't considered that it was the blower in the glove box area. Maybe I'll put my head in between the glove box and the seat and see which direction the sound comes from.
Originally Posted by 87geeinn
If no one is sitting in the passenger seat, none of the dynamic functions should be active on that seat IIRC. Not entirely sure on that though.
Oh, I definitely hear it when I'm driving solo.
Originally Posted by 87geeinn
You can unplug the air pump fairly easily to help narrow down the problem. The pump is in the driver side (US models) trunk area, sandwiched between the rear quarter panel and trunk carpeting/liner. Remove the trunk floor liner from the car, remove the foam tray piece directly behind the back seat, pop out the plastic rivets on the trim piece that runs from the trunk latch to either side of the trunk closest to the bumper, then remove the driver side trunk liner panel (few pop out rivets, light fixture, and the 12v socket. Doesn't have to come all the way out. You'll see a black/gray box covered with gray foam insulation directly forward of the rear taillight assembly/behind the DVD drive and fuse panel. Just unplug the wiring connector. It won't cause any warning lights or anything.
OK. Thanks. But, if the pump is way back there, would there even be a corresponding pump under the seat?
Also, I'm not convinced that my dynamic seats work at all. I've never experienced any dynamic features in the short time I've owned the car. I've been focusing on repairing/refreshing other features.
But, if the pump is way back there, would there even be a corresponding pump under the seat?
Also, I'm not convinced that my dynamic seats work at all. I've never experienced any dynamic features in the short time I've owned the car. I've been focusing on repairing/refreshing other features.
No additional pump. You can pop the back of the seat off and see how it all works (or doesn't, lol). There's like two screws or bolts at the rear, bottom of the seat and the back just lifts off. From there, you'll see all the air lines to the various bolster bags run from a central distribution block about dead center in the middle of the seat. The lines can break but more often than not, it's the side bolsters which split at the seams. This is the case in my car. My dynamic seats worked up until a few months ago and I traced the problem a cracked driver side bolster. Tucked it back in there and said **** that to the repair. Some have come up with nifty ways to reseal the seams but not worth the effort IMO. I never really use the Dynamic function anyway as it's distracting as hell while driving. It's more of a conversation starter for uninitiated passengers. Same with the "Pulse" function. It's a in/out lumbar pulse which only goes for five minutes. Not really a massaging seat as you'll sometimes it see touted as. I think there's a reason MB got rid of all that in the subsequent E63s.
Last edited by 87geeinn; Nov 24, 2021 at 07:43 AM.
@CQHall - when you hear the whirring sound selelct Off on the dash HVAC controller and see it that stops the sound. If not then it is likely some other device. Under the passenger floor is a void where a number of controllers and such are located. You may something in there (maybe aftermarket) that is making the noise.
For your Dynamic seats - using your owners manual as your guide if you need it, you can operate three of the air bladder functions - side bolsters, lumbar bolsters, and the thigh bolster on the front edge of the seat bottom. You can fill the bladders and empty them to refill. You should be able to feel the filling of the indivudal bladders. If any of the red lights on the switches are blinking, that is a fault indication. Even though you can feel the bladders filling, they can have a leak that will allow them to empty eventually. If you have access, the the MB Star diagnostic tool can do a test procedure where it will go through each of the four bladders to determine if it functioning properly. Each individual bolster test cycle is about 5 minutes.
The whirring sounds comes on soon after starting the car and at random times during a drive.
The whirring occurs when the HVAC is off.
The sound seems to be coming from either under the passenger seat or low in the back of it.
The sound is not coming from the glove box area.
I am able to make the same (or very similar) sound when I manipulate the Up, Down, and "+" buttons indicated in the photo below. The "-" has no sound, nor do the other buttons.
When I press "PULSE", the red light flashes a few times then stops.
Once when driving, the sound came on again. It usually lasts maybe 2 minutes, but when it started, I immediately pressed the "+" button and the sound stopped.
My guess is that it's related to whatever motor or fan those buttons activate.
The whirring sounds comes on soon after starting the car and at random times during a drive.
The whirring occurs when the HVAC is off.
The sound seems to be coming from either under the passenger seat or low in the back of it.
The sound is not coming from the glove box area.
I am able to make the same (or very similar) sound when I manipulate the Up, Down, and "+" buttons indicated in the photo below. The "-" has no sound, nor do the other buttons.
When I press "PULSE", the red light flashes a few times then stops.
Once when driving, the sound came on again. It usually lasts maybe 2 minutes, but when it started, I immediately pressed the "+" button and the sound stopped.
My guess is that it's related to whatever motor or fan those buttons activate.
Does this help with the diagnosis?
The buttons on the seat activate the air pump (located in the truck left side) to fill the various air bladders in the seat or deflate the bladders. The Pulse function simply fills and empties bladders in a rotation pattern to create a massage type of effect. There is is no fan as part of that system. The only fan with the seat is for the ventilation function. The fan only moves air through the seat for evaportive cooling. I would suggest remove the back cover on the seat and see if that will help you locate the source of the sound. To help to locate the sound it may help to use a section of heater hose with one end at your ear and the other end moved slowly around ithe are the sound is comong from. The hose will help pinpoint the source of the noise.
The buttons on the seat activate the air pump (located in the truck left side) to fill the various air bladders in the seat or deflate the bladders. The Pulse function simply fills and empties bladders in a rotation pattern to create a massage type of effect. There is is no fan as part of that system. The only fan with the seat is for the ventilation function. The fan only moves air through the seat for evaportive cooling. I would suggest remove the back cover on the seat and see if that will help you locate the source of the sound. To help to locate the sound it may help to use a section of heater hose with one end at your ear and the other end moved slowly around ithe are the sound is comong from. The hose will help pinpoint the source of the noise.
Maybe it's a servomotor and not a fan? Could there be a motor in there trying to adjust the bolsters or move the lumbar support up/down?
I'll see if I can remove the seat back tomorrow and see what's up.
OK. I get what you are saying now.
I just tested a few things.
The dynamic seat button won't activate if someone isn't sitting in the passenger seat.
I did hear and feel the driver seat lumbar support inflate and then nothing more. Maybe the pump detected an issue and quit?
When the driver's seat was inflating, it made the whirring sound. So, it was air that I was hearing, not a motor.
It all makes sense now.
With that being said, I wouldn't be surprised if my seat bladders and hoses needed a complete overhaul. Whelp...I'll add it to the list of stuff I gotta do...
Maybe it's a servomotor and not a fan? Could there be a motor in there trying to adjust the bolsters or move the lumbar support up/down?
I'll see if I can remove the seat back tomorrow and see what's up.
OK. I get what you are saying now.
I just tested a few things.
The dynamic seat button won't activate if someone isn't sitting in the passenger seat.
I did hear and feel the driver seat lumbar support inflate and then nothing more. Maybe the pump detected an issue and quit?
When the driver's seat was inflating, it made the whirring sound. So, it was air that I was hearing, not a motor.
It all makes sense now.
With that being said, I wouldn't be surprised if my seat bladders and hoses needed a complete overhaul. Whelp...I'll add it to the list of stuff I gotta do...
Glad to hear you are making progress. Yes, with the age of our cars they all are typically in need of new bladders. Thankfully, MB still has them to sell - but of course, they have the MB tax applied.
...You'll see a black/gray box covered with gray foam insulation directly forward of the rear taillight assembly/behind the DVD drive and fuse panel. Just unplug the wiring connector. It won't cause any warning lights or anything.
You sure it's not the blower motor under the glove box area? Those are notorious for making squealing noises and just generally being a PITA. A little off topic but that problem is easily remedied by cramming wheel bearing grease in the LOWER fan bearing. It's absolutely not necessary to replace the blower assembly or remove it for greasing. It's the bottom bearing that causes all that racket. Back on topic though...
BTW, thanks for this tip. I noticed the squeak on occasion and I skeeted some silicon lube spray (using the narrow nozzle) up into that lower bearing this evening. If that doesn't work, I'll go buy some grease.
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