Mystery Buzzer and Rear Window Defogger Relay Cycling

[stevenlee]

What could be causing this?

My car developed a piezo buzzer sound that sounds once every second for 7 beeps followed by a ~2 second silence and then it repeats the 7 beep cycle.

This happens only when the ignition is on and the driver's door is closed.
When the driver's door is opened, the buzzer stops.
Sometimes this cycle runs constantly. Sometimes it stops a few seconds.

The buzzer seems to be coming from under the driver's side dash.
It's difficult to find the buzzer because the sound goes off when the door is opened.

Sometimes, when this buzzer is activated, there is an accompanying cycling of the Rear Window Defogger Relay in the engine compartment fuse box.

Background:
Yesterday I removed the gauge cluster and the center console to do some wiring.
Also did other work such as replacing and testing turbo waste gate actuators.

Any help on diagnosing the cause of the buzzer and rear window defogger relay cycling would be greatly appreciated.

 

[stevenlee]

UPDATES:

11PM-
The battery was low so I put it on a charger. The buzzer now constantly beeps and the rear window defogger relay constantly cycles on and off... no 7 second cycles. I don't know if the charger is the reason for the change to constant cycling.

2AM-
New clues to solve the mystery....
1.When I turn on the cabin dome light, the buzzer and defogger relay stop their constant cycling (on and off).
2. My LED dome lights are very dim now. They used to be very bright.
3. When I put my key in the ignition (without turning it) I hear a faint beeping that sounds like a piezo buzzer just starting to sound. This beeping only happens when the door is open. When I close the door, the louder beeping begins along with the cycling of the defogger relay.

I can't figure out what is causing the beeping and cycling of the defogger relay.
It's even more intriguing why these symptoms change when I open the driver's door.

Does anyone have any ideas or theories about what could be causing this?

 

[JD Cross]

Steven
I'm not the best source for this but I had very similar seemingly unrelated electrical glitches on my BMW motorcycle.
I live on the ocean and the cause turned out to be a corroded ground wire due to salt content in the air.
Apparently the salt, moisture and aluminum can create an electrolytic reaction like on a boat.
Your air has a lot more salt in it than mine so it might be worthwhile to check the battery terminals and where the grounds are attached.
Jim

 

[comtec]

The integrated control unit is mounted on the under dash fuse box at the drivers feet. It contains the defogger circuit, the buzzer for the lights on/seat belt/key reminders and also has connections for the door switches. You didn't say what you were wiring up but did you tap into any of the existing wiring that may go to the integrated control unit?

Do the audible reminders work? ie.. lights on/seat belt/key
Remove the panel covering the fuse box and with someone holding the door switch in see if you can tell where the sound is coming from.

Mike

 

[stevenlee]

Jim and Mike, thanks for your comments.
The audible reminders do NOT work.

I laid upside-down with my head in the foot well and listened for the piezo buzzer sound but I couldn't tell where it was coming from.

I notice that there is a very faint chirping beeping when I put the key in the ignition (without turning the key) with the door open. When I close the door, that beeping stops.

About 7 years ago I changed my dome lights to LED. They used to work fine but are not functioning properly now. They're dim and they flicker on and off with the beeping sound.
I'll try removing the LED dome lights and see if that affects the mystery beeping.

Edit: With the dome light removed, the faint beeping is still present with the key in the ignition and the door open.

 

[comtec]

You may have an issue with the integrated control unit. It may be going bad or you could be having an issue with the wiring to it. Before buying a new one (approx $340) see if there is someone that you can swap with temporarily for testing. The faint beeping you heard with door open is probably the buzzer inside the integrated control unit for the key in reminder. It being faint is one problem but not the only one because the lights on reminder has a chime instead of using the buzzer. The LED's may be acting up because of the ICU or possibly they could be causing a short in the ICU.

Mike

 

[stevenlee]

Comtec, thanks for your post.
Yesterday I decided to break out the service manual and remove and test the integrated circuit.
The manual said to install the "shorts" in roughly 5 locations for the SRS system before removing/disconnecting the integrated circuit module to test it.
That will include various dis assembly including removing the glove box to get to one of SRS jumper plugs.

Is there another way to remove the integrated circuit and test without having to access and short all of the SRS plugs?

This is turning out to be a much bigger issue than I originally thought.

 

[PS172]

Well for strange weird buzzing sounds, I have a tough one..... my car was on the lift at home for about 7 weeks waiting for an engine, the battery was disconnected and still there was a strange low frecuency buzzing sound akin to a tuning fork sound, about 2-3 seconds long, every 3-4 minutes... it appeared to come from somewhere in the area of the gas tank.... no juice in the the car, battery disconnected, any ideas.

 

[comtec]

If your talking about removing the integrated control unit per page 23-166 (97-05 man), at the top where it says SRS is just a reminder that SRS wiring is near. You should only need to use the shorting pins when working on the SRS system. As long as your careful you shouldn't have an issue removing the ICU but it wouldn't hurt to remove the ground cable from the battery.


PS172
I think that is the purge valve for the fuel tank vapor control

 

[PS172]

Sounds posible, but from where did it get current if the battery was disconnected???

 

[Larry Bastanza]

Open the gas cap....

Well for strange weird buzzing sounds, I have a tough one..... my car was on the lift at home for about 7 weeks waiting for an engine, the battery was disconnected and still there was a strange low frecuency buzzing sound akin to a tuning fork sound, about 2-3 seconds long, every 3-4 minutes... it appeared to come from somewhere in the area of the gas tank.... no juice in the the car, battery disconnected, any ideas.

 

[comtec]

Sounds posible, but from where did it get current if the battery was disconnected???

I believe it's pressure operated, not electrical.


Mike

 

[PS172]

OK... NEXT TIME I HEAR IT WILL OPEN THE GAS CAP..... so many issues in 9 months of ownership and about $10k...but now I think they have been sorted out, rebuilt engine now with 800 miles on it, so far so good, all other items taken care of, the forum is great!!

 

[comtec]

OK... NEXT TIME I HEAR IT WILL OPEN THE GAS CAP..... so many issues in 9 months of ownership and about $10k...but now I think they have been sorted out, rebuilt engine now with 800 miles on it, so far so good, all other items taken care of, the forum is great!!

Fyi... This is normal. Hear mine almost everytime i get back from a drive, sounds like a sick cow.

Mike

 

[stevenlee]

Can the Integrated Control Unit be unplugged without connecting all of the SRS short connectors as described below?

The Under-Dash Fuse Box has a yellow, SRS connector at the top left corner. It looks like the Integrated Control Unit plugs into that fuse box.

The 1995 service manual says "Before disconnecting any part of the SRS wire harness, install the short connectors (see page 23-328)."
That section shows short connector locations at: the steering wheel, behind the glove box, left side seat belt pretensioner and right side seat belt pretensioner. To get access to all of these SRS short locations various interior panels and the glove box would need to be removed.

The SRS wiring precautions read: "If you ever remove the under-dash fuse box or the SRS main harness, disconnect the SRS connector from the fuse box."

If someone can confirm that I don't need to install all of the SRS shorts before removing the Integrated Control Unit, that would be great!!!

 

[JD Cross]

Steven
Any news on your electrical issues?

 

[stevenlee]

Steven
Any news on your electrical issues?

Haven't solved the buzzing/integrated circuit issues yet.
I've been busy with work an other projects.
I'm getting the car ready for a new Series 2 AEM EMS from SOS that will be installed later today. A tuner is flying in on Thursday and will begin tuning on Friday morning.

I had an issue with the AEM dual wideband sensors. They both suddenly stopped working a few weeks ago. After much investigation I found that the power wire was improperly crimped on the AEM's Deuche connector. Whoever crimped the pin at AEM crimped onto the wire's insulation in 2 places instead of crimping onto the bare copper wire in the first location and crimping on the insulation in the second position.

Today I installed an AEM failsafe flow meter for my FJO water/meth system. The water/meth system is unusual in that it utilizes full pump pressure when activated. High pressure is better for atomizing the spray. It has and injector that can be pulse width modulated to meter the flow of the water/meth as boost raises. Unfortunately, Holley bought out FJO a few years ago and they no longer support the system nor can they provide much info about how to control the injector's duty cycle. With the AEM failsafe flow meter, we will be able to test different frequencies and duty cycles and see the effect on the volume of the spray.

Hopefully the EMS installation and tuning will all go well and I'll be able to work on figuring out the mystery buzzer.
I don't know if the Integrated circuit unit went bad of if it is a wire/connector issue.

I've been working 70-80 hour weeks for the past 10 months and haven't had much time to drive or maintain the NSX. It is getting some extra love though. In addition to the the new Series 2 EMS, I also got the ABS upgrade kit from SOS and will be installing it soon.

These upgrades are driven by the fact that I'm planning on shipping my car to San Diego in September and taking a 4-5 week road tour to NSXPO where I plan on tracking the car for the first time.

Hope to meet up with some fellow NSX owners on my double, cross-country journey.

I sure would like to get that mystery buzzer issue fixed before the big trip!

Aloha,
Steve