Cratecruncher

I've done a search and can't find where anyone has had this issue. There is an intermittent buzzing sound coming from the instrument cluster area. It occurs with ignition on or off, driving or parked. Sometimes it's hardly noticeable, other times it drives me crazy! I have an old B1001 code but have never had issues with the ignition switch. the car only has 55k miles. One thing I noticed is that when the sound is present I can place the key in the switch and open the drivers door to start the key warning chime. The chime comes from the same place as the buzz, works perfectly, and the buzzing sound stops for a 10 to 15 seconds before resuming. I can find no other electrical issues.

I suspect the circuit is starting to ground somewhere causing just enough voltage to emit sound from the chime but haven't a clue where to start looking. Suggestions anyone?? I need to attend to this for my sanity on long trips and for fear I'll be stranded with a dead battery at some point.

dadaroo

I think the chime feature is triggered internal to the IPC based only on serial bus input provided from the BCM. Maybe some are directly from modules via the serial bus. Not sure how external inputs would cause a buzz in the chime if it works fine for other signals like your door. Kinda sounds like an internal IPC board issue.

Will have to look at the code and FSM when I get home and see.

In the interim, clear all your codes after recording them. Then wait until it happens again and pull your codes and post them.

Cratecruncher

Thanks for the help! I'll clear the B1001 H code and see if it comes back. I have a set of manuals for the car but can't seem to find where the chime even is in the circuit. I suspect its soldered to a pc board behind the instrument cluster?

FWIW, The car has an aftermarket column lock bypass I installed several years ago. I've had no issues with it.

dadaroo

Yes the speaker is on the back of the TPC. Here are some pics to help:

http://forums.corvetteforum.com/c5-t...post1570380674

After you get any codes, we may want to pull the two IPC fuses to make sure it is the speaker making the noise.

Bill Curlee

There is a speaker CHIME driver / amplifier circuit on the main IPC Circuit board. We DO NOT have access to any internal IPC circuits schematics or component documentation.

There have been several C5 owners who have had the chime circuit BUZZ and YEWS, it can and will drive you insane.

Two options:

Clip the wires on the speaker.

Get creative and trace the circuit and find the IC that does all the functions. See if you can replace it. NOTE. It most likely does not have any markings on it.


Bill

Cratecruncher

Dadaroo, thanks for the great pics. It sure helps visualizing what I'm looking for and the sound emanates from the lower left of the gage cluster right where that speaker is in those photos.

Bill, thanks for the info and suggestions. I know it's probably wishful thinking but have there been any instances of solder joints going bad on that IPC? I hate to unplug the speaker. It feels like admitting defeat, haha.

Update: I cleared my B1001 H code yesterday and it hasn't returned, yet.

Cheers,
Mike

dadaroo

Any solder joint can go bad, but have not heard of a known concern for cold solder joints in the IPC. Normally what that does happen it just degrades the circuit or just opens and fail the circuit. You seem to have an issue that something is shorting internally even when the car is off. I rule out a bad solder joint as a likely source. Sorry.

Cratecruncher

I suppose I've gotten as far in this as I can without turning some bolts and getting my hands dirty. I'll pull the board and see if I can find anything. From the video of that '99 board it looks like just about all of the IC's have markings. Whether they're available or not is another question.

On a broader note, I wonder if GM will ever release the full circuit diagrams for these boards. I know this stuff is proprietary but at some point....