Ivan I

I am chasing down a gremlin in my 97 Boxster and could use some help! At around 65 mph, I get a really annoying warning buzzer that sounds higher pitched than the standard seatbelt warning buzzer. It is not a strong sound in that it comes and goes like something is shorting out somewhere causing a circuit to close and sound the alarm. The sound stays on at and gets stronger at higher speeds.

My initial thought was the rear spoiler, since it comes up at about that speed. I pulled the fuse to eliminate that circuit but the sound was unchanged.
Next was the anti theft system. So, I unbolted the drivers seat and pulled the fuse. No change.
ABS system. The Boxster's speedometer system pulls it's signal from the ABS system. Pulled that fuse, no change.

I have been working on the car quite a bit over the last few months. And am suspicions of my own work. I changed the clutch slave cylinder, put new bearings in the tensioner pulley, and put on a new accessory drive belt. Oh yeah, and a new cooling fan on the drivers side radiator. I am wondering if there is something i could have damaged that would cause this sound.

I am going to go record the sound later today and will post the sound file. Any good ideas?

Ivan I

Update:
When a warning buzzer isn't a warning buzzer: I removed the instrument cluster and found the little horn on the back. Before I disabled it in a fit of frustration, i decided to drive the car and see if the buzz was still there. I little strange, driving a car without instruments! And i am glad i did. The buzz is still there.
The sound seems to be coming from the top of the HVAC system. I disconnected the LED for the car alarm. No change. What could be up there making that noise?

Ivan I

removed all the trim that pushes up against the windshield and the buzz diminished; but, i also found a loose black tie wrap that runs from the top of the heater/AC unit to the floor. The buzz is still there; but, i no longer think that it is electronic and it's not as persistent. I found an old post in the 996 forums where a guy got a leaf stuck in the Heating/Cooling vents that could have been a similar sound. And I have found a lot of foam coming out of my vents. I thought the foam was from rodent activity; but, the little jerks found some little blue pellets that didn't agree with them.

Does anyone know if that black tie wrap is a stock installation practice? I will post a picture later; but, it is visible without removing any trim just to the right of the accelerator pedal. It runs from the floor hump to the top of the HVAC system.

Has anyone ever felt like the guys from the Curse of Oak Island?

mikefocke

So a 20 year old car, foam has dried out as has glue and foam is bouncing around in your HVAC air vents. Not unusual. Search is your friend as there are dozens of appropriate threads.

As to the wire, see if ground or positive and if positive under what conditions.

Ivan I

Wire, what wire. Did you find a loose wire?