I have a mystery noise coming from the drivers side somewhere in the dash, I think. Only noticed it recently.

It is a high pitched whine type noise that would be similar to the noise a die grinder would make. Maybe not quite as high pitched but similar. Maybe a solenoid type whirring sound. Hard to describe it exactly.

It starts out as this high pitched sound and runs for maybe 15-20 seconds, slowly decelerates in speed, then stops. After a pause it will start again and run for a shorter cycle and finally just get to the point where it will just "bump" and then continue that.

Started to install a Hurst shifter when this became evident but I did hear it before I ever took anything apart. The car is parked next to a shop where they are always using power tools and this may have been going on for sometime and I just didn't notice it.

I have done several things to the car from taking the passenger side carpet out to dry (stopped up drain), replaced the emergency/signal flasher, and installed the CLB unit and never heard the sound before. I recently replaced all the inside lights with LED lights so maybe that had something to do with this? Don't really see how but that is the last mod done before the sound became evident.

While installing the shifter with the drivers door open the sound would start and then the reducing cycles would start until almost no length to the cycle but still trying to engage. Then if I got out of the car and closed the drivers door and came back it would start all over again with the long cycles of sound and then progressively get shorter and shorter on the cycle times.

Can't imagine this is helping battery life.

Anyone?

 

It's probably your make up air pump which is part of the emissions system. It is located under the drivers side headlamp assembly and makes a high pitched whine on startup or under certain other conditions.

 

Hmmmm.....something tells me the OP was not swapping out a shifter with the engine running...

 

No, didn't have it running and the key was out of the ignition, if that matters. Haven't really hung around it so see if this continues to happen while I am not present. Heading to the shop shortly to see if it is still going on.

 

I had that same problem on my old C5. I would hear it after I shut the car off. It just eventually quit (probably meaning whatever part it was burned out) but I did read another post on the forum during that time about a guy who's windshield washer pump kept getting power after the car shut down and it would whine, eventually fading away after a bit. I guess try there first.

 

Well I messed with it for about an hour this afternoon and could not get it to repeat with the frequency it did on Friday night when I was installing the shifter. I only got it to do it three times during that hour. I let the car sit with the doors open until the interior lights went out. A little later they came back on and the noise could be heard.

I then sat down in the car and it did not do it for a period of time so I closed the door and it started again. After it quit I tried opening and closing the door to try to get it going again but did not so I am assuming closing the door was just a chance occurrence.

I then turned and started to exit the car and it did it again. Tried moving in the seat/out of the seat a few times and could not get it to repeat, so again coincidence.

Strange.

 

I have found the culprit! It is a motor in the seat that I think is supposed to air up a bladder maybe?

I do not have an owners manual on seat controls and their function. The controls that move the seat forward and backward, tilt up and down work fine.

There is another set of controls that I think do the lumbar that is not working correctly. Two switches that move forward and back and one that moves up and down. When the noise starts if I move the up and down switch it will stop the noise until I move the switch to the neutral position. Neither of the switches that move forward and backward do anything.

On the passenger seat all the switches work as if they are airing up or deflating the lumbar. Drivers side do nothing until the motor starts to run itself and then the up and down switch will cut the motor if I move it up and hold it. When I release it is continues to run until it cycles itself off. Sometimes it will cycle for shorter and shorter lengths of time until it just stops.

Can I disconnect just that part of the controls or do I have to disconnect all of it.

Either controls are dirty and not working properly, pump is going, or the whole thing is gone.

Suggestions?

 

The bladder may have a hole in it, it is literally a plastic bag.

 

Would the bladder having a hole in it keep the controls from working on the side of the seat?

For now I just unhooked the pumping power harness. No codes or anything.

I did take the control section apart to see if there was any corrosion or broken leads. Everything looked fine. Assuming I have a toasted pump.

 

This is purely speculation, but if the bladder has a leak or a loose hose, I assume it will not trigger a sensor to send the message that it's full, "shut off pump". As for the other controls, may be related to the pump working overtime trying to fill a defective blader. There are some posts here about replacing seat covers, I have seen excellent photos of the bladder set-up in the seat, this may shed light.

 

I had the same weird noise since one year on my 2000 conv.
It's the alarm bells that is trying to find the contact. I asked the same question on this Forum 3 weeks ago. I received some good answers. First, take off fuse no 17 (on passager side on the floor) for a few seconds and put it back. It will stop the noise maybe completely. Second, a guy told me he simply disconneted the bell speaker behing the cluster (dash).

But I'll try to find all the answers I received and I'll let you know about it.

Excuse the writing, french is my first language.

Good lock

Michel

 

I did find the thread that touch that problem. Go to this Forum,
C5 TECH August 18th 1:18, read all the answer and let me know how it helps you. I think it's name "electronic dash noise".
Good luck
Mic

 

My passenger seat did that last fall. I think the door wasn't closed right or the window wasn't right up because there was moisture in the carpet under the seat and the switch assembly seemed to have some moisture in it too. I dried it out and it's been fine since. I did take the switch completely apart to find the moisture in it. I believe I had to cut some melted plastic tabs and then re-melt them to do it though. It really wasn't made to come apart again.

The bladder system is pretty dumb. It does not sense the pressure or attempt to maintain the pressure. My one bladder in the drivers seat does not work and I can run the pump but it never runs by itself.

If I remember correctly, the two that move forward and back are bladders in the seat back (like lumbar) and the one that moves up and down will tighten the sides boosters, or squeeze the sides of the seat back in to "tighten" the seat up to your torso. One of the lumbar bladders doesn't work on my drivers seat but it has no affect on the seat operation (other than not inflating obviously).

Peter

 

Thinking about recovering the seats so will just leave it unhooked until then. Doesn't throw any codes so not really bothering anything. I never used the lumbar thing anyway but would like to have it work correctly. Sounds like a good winter project.

Thanks to all!

 

Someone posted here to get the small bands for taking blood pressure from some place like Walmart and using them to replace the bladders. I don't know what the proper term for them is but I'm sure you know what I mean.

Peter

 

That sounds like a great idea. Thanks!