Hello everyone, I have an issue that needs some attention. There is a silver metal box in the dashboard on the passenger side that is visible when you remove the lower dash plastics. Its been making a noticable buzzing noise since I reattached my battery cable. ( Batt has been unhooked for several weeks while I redo my interior)

It doesnt make the buzz noise unless the key is in the on position so the dash lights for airbag and choke and all that come on. For the first few seconds it makes a higher pitched intermittent squeeky buzz like static interferance on a radio, then it goes to a constant low tone buzz like a beard trimmer with a low battery. I cant tell if it does it with the engine running since the engine is pretty loud.

I recently stripped the interior out of my car (91 Firebird with Aero package) and installed a new overhead console and auto-dimming rear view mirror. Both items are OEM from an 87 GTA. Im not sure if installing these things caused the problem or not, but if I fully disconnect both the new electronic items and put it back like it was stock, it still makes the noise.

Its possibly its been doing this all along and I just couldnt hear it throught the plastic trim, but I find that unlikely, since its pretty noticable even from a distance if the room is quiet. I have no idea what the box is for so I have had a heck of a time trying to look up any info on it, and Im clueless when it comes to wiring and electronics stuff anyways.

Anyone had this problem before or have any ideas about what could be causing this problem? I attached a pic of the silver box in question. I stuck my ear right to it and theres no doubt its the box making the sound and not something else. Any help would be appreciated. Thanks.

 

thats your car's brains. muahhhaahaa.. brainssss.. but seriously, its called a ECM. Search ECM. and for the buzzing noise, maybe a relay or something. check my story out....whenever i pop the hatch using the button on the dash, i always hear that noise youre talking about for a second. If i had a problem like yourself, id "slap test" the ECM aka silver box. slapping it while the engine running will help determine if theres any loose electronic components that maybe contributing to the noise-noticeable if the engine boggs or surges from slapping it. In my instance- its just a relay for the hatch release solenoid. but if its making noise, maybe its your injector wiring. typically, the ecm controls each injector. Id check fuses, and try "slap test" peace

 

Hello, thanks for the reply. I tried the slap test but I couldnt get it to do anything, the buzz just continued on with no change in pitch. No lights flickered, and everything appears to work fine. All switches work as intended as well. Only thing I couldnt check was the stereo, since its got a short and is currently removed. I have to do the test with the key turned on and the engine off, since the noise of the engine totally drowns out the buzz. When I do start the car, it starts fine and idles fine, but while its running, its impossible to hear the buzz from the box. I cant drive it around or run it long since its pinned in my shop. When I can get it out, Ill do a more extesive slap with it running and driving.

The buzz starts about 2 seconds after I put the key in the "on" position. It starts as an intermittent squeeky static noise, then goes to a steady buzz after about 1-2 more seconds and stays that way until I turn the key back off. I can feel no heat or vibration from the box, but that noise is making me nervous. Im afraid to leave it on for long out of fear it will burn or short something out.

You mentioned something about injectors, I dont know if this would matter, but my car doesnt have tpi or mpfi, its a base model 305 with the throttle body setup. Everything in the car is still to factory specs with the exception of a few additions to the interior, its never been modded by anyone, since I am the only owner and like to keep things stock.

It also just occured to me that I did a gauge cluster swap for a 90 model trans am gauge setup with the 140mph speedo in it. That part was installed at the same time as the mirror and console, could it be causing this problem? It works fine and all its lights come on properly.. but who knows.

Hopefully I can get it resolved this weekend so I can put my interior back together a bit. Im gonna leave it apart until I find out whats going on, just in case.

 

un plug the battery and take the lid off and see if you loosened something when you were banging around to redo the interior. its a computer its not supposed to buzz - something is wrong and many things can cause the buzz.

 

Thanks for the suggestion Tony. I pulled the cover off and everything looked like new and was nice and tight. None of the capacitors looked swolen or leaky, and no dark areas around the contacts. I decided to put the power back to it while the cover was off so I could use the funnel to the ear trick and find exactly what part was buzzing. Turns out it was one of those little parts right beside the plug in for the wiring harness, just inside the silver case. Looks to be a copper coil of some kind perhaps a relay? Im not very wise in these matters. The numbers on the thing are 16120861 TDK, second line is JAPAN 9028. I have a pic attached with the noisy little booger highlighted.

Could this part be bad itself, or perhaps point towards what the real problem might be?

Note: I didnt pull the board out, I just examined the front of it with the case off, so I dont know how the pins look from the back side. I can check if needed.

 

thats a transformer man, but typically i can find those in big relays too. i wouldnt worry about the noise unless its ungodly bad. then maybe you'll just have to get a new ecm. But but i dont know man. i cant help you. but im confident someone will know a bit more. im not even sure if that is a ecm, if it has 16 plus wiring going to it, then yeah its most likey the computer. if you like taken the time to get more pictures, try that. id like to see other angle maybe a computer number. Theres a lot of genius' on here. just got to find them GRRR

 

Hello again, thanks for the input. I got a few more pics of the thing, it definately has 16 or more wires going into it, its a decent sized harness. It also has a nice big sticker on the cover with all its numbers and a bar code. I got a pic of it and the harness plug both.

I wouldnt say the noise is ungodly bad, but its loud enough that I can hear it from the other end of my shop if its quiet in there (25-30 feet away). Im afraid to leave power to it for long in case it causes something to burn up, thankfully its gonna be a month or two before the car is all fixed up and ready, so hopefully that is plenty of time to find the answer to this.

If more pics are needed, I will gradly provide them. Just let me know what is needed.

 

The silver box that is buzzing is obviously a buzzer.

 

ECM , get another one, there cheap.

 

Thanks guys. If I replace this one, do I search for a new one using the SERV. NO. 1228874? I found several with this number but the other numbers dont match. Is the Serv No the only number that matters?

From my search it looks like this is an ecm/airbag control module. What are the chances this part itself is bad and not something else leading to it? Seems like a super easy fix if all I need is to replace the module. Could I be so lucky?

 

That is the airbag control module, it controls the airbag. You should be very careful when dealing with airbags. Air bag stuff almost always uses yellow wires and connectors, so there easy to spot.

The airbag can go off if you mess something up. Before messing with the airbag you should always disconnect the battery and touch the battery cables together to drain all power from the system.

If you want to keep your airbag I would suggest replacing the control module and checking out the rest of the system.

Or you can disable/remove the airbag from your car.

I put an aftermarket steering wheel on my car so I no longer have an airbag(I don't like airbags anyway). I took out the SIR (airbag) fuse and the light bulb (in the gauge cluster) and removed the airbag and steering wheel. I also plan on removing the control module and maybe even the airbag wiring.

 

I did some more research and it looks like this thing is an airbag controller or SRS/SIR module, not the ecm. Looks easy enough to change, Im just not sure if the part itself is bad or if something leading to it is causing this buzz noise. Anyone know what the chances are of fixing this by replacing the module, or do I have a problem elsewhere that just happens to be causing this thing to buzz?

The thing has me pretty nervous now that I know what it is, Im afraid the damn thing is gonna randomly blow out in my face or something. Airbags to the face hurt like mega-hell for those who havent experienced it.

EDIT: Madmax, you must have been posting the same time I was. Yeah I know where you are coming from about the danger of those things going off, and only work around it with battery unhooked. I want to keep the bag if I can since I like the look of the steering wheel.

I couldnt see anything wrong with the wires along the floorboard or center console (two yellow and two white in a seperate retainer). I dont know how to go about checking the three sensors so I left them alone. Unless their is something else I can check for a possible cause, I may just go ahead and order a new module and see if it stops the problem. I wonder what would have caused this? do these things just go bad like that over time perhaps?

Note: If I do decide to just take the module and fuse out and not replace it, is that all it requires to disable the system, or do I need to remove all the sensors too? I want to keep the airbag steeringwheel.

 

I'm not exactly sure how to check an airbag system I've never really had to diagnose one before. I would assume its just the computer because that is the most fragile part of the system since it uses a circuit board with small fragile circuits and the car is almost 20 yrs. old its not uncommon for computers to fail after that long.

Removing the fuse will disable the system by cutting power to the control module. I was just thinking off removing the module because its just taking up space and is now useless.