No, not the Yugoslavian entry in the 1974 Eurovision Song Contest. It's the sound we want from our Bay lights on warning, if fitted (or added if not). The stock US-style electromechanical buzzer sounds awful, and warning "relays" fitted to earlier Golfs and like (which are still around on eBay) just sound like a badly-programmed Sinclair ZX81. We want a nice, sonorous "Bong!", as on modern VWs. Unfortunately, bonging duties are performed by a tone generator built into the dash, so not an option. Enter the BMW Auxiliary Bonging Unit, built into the footwell of various Bimmers from a decade or two ago, to support - I believe - various options like reversing sensors. BMW part number 8360995. There seem to be various versions, but the one with the green base gives you the range of pinging and bonging, to use as you wish. Also seem to sound better. Loads on eBay for a tenner or less. All tones apart from T5 are triggered by taking the appropriate contact pin low (to earth). T2's the easiest for triggering from a low-going door switch. It's quite pleasant, and runs continuously. T5's actually mellower, but needs to be triggered by a positive level on the pin, so some transistor-age necessary to flip the door switch signal upside down. If you've got a modern ignition switch with stuff like key-in-switch outputs, with a few trannies an a bit of diode logic, you could have a whole warning symphony going. I was lucky enough to get the original connectors with mine, but easy to solder leads on. Needs an unswitched +12 supply, but only consumes about 0.5mA when it's idle. Be warned: these are bigger than you think, as they've actually got a real loudspeaker in, rather than a piezo transducer. Compare with the "relay" in the background. Here's a Japanese fellow demonstrating what's available.
Just a little bit of it; when I fitted the towing kit the ‘bing bong’ was replaced. It was on my 1994 525ix, not many made RHD, I had the saloon version with a manual box. No aircon and not even a radio as standard even though it was SE spec. It did have indicators, just pull the stalk and those four headlights got the plebs out of the BMW lane. Possibly the best family car I’ve had. https://www.carfolio.com/bmw-525ix-24v-170412
Did you manage to get this wired in as a 'Lights On' warning when you turn the ignition off but still have your headlights on? I'd love to know how you wired it into your T2
I did, and it works really well. Lights on, door open and keys out, and it makes a pleasing bonging noise. I'll do an update, if I can find the scribbles showing how I wired it.
Here you go. As you haven't got a key switch, much easier. Connect bonger as shown. Bit brutal for a bit of electronics that should be powered all the time, then triggered, but it doesn't seem to mind. Connect T2 to -ve or T5 to +ve for alternative bongs. Connections are marked on back of unit. All the tones are -ve triggered, apart from T5. Mine was a bit more convoluted, as I have relay driven by the "key in" switch to power the radio, plus my alarm was getting confused by a current path that made it think the door was always open <edit> Sorry, meant T5, not T4