aftermarket backup sensor so loud

Ok, the point was to control the volume so if I'm arriving somewhere and the kids are asleep, I could put the volume very low or even off and still be able to use the LEDs on the backup display for assistance in backing up. A loud/obnoxious beeping sound would definitely wake them up, making for cranky kids and wife. SO, hiding it behind a panel kind of defeats the purpose. Plus, isn't reinventing the wheel the whole point to boards like this? Who wants to re-use the same wheel!

Why not just run an on/off switch to the front of the vehicle.

Yep, did that. You can't use the LED portion when you shut off the whole system, though.

I meant for the speaker only.

Yea, that's an option - you're kind of going back to the beginning replies of this topic. Some people didn't seem to think it would be a good idea to desolder the exising speaker because it might screw something up in the board. That's what I was asking, though, whether I could take the speaker out and either put in a switch or an L-pad.

Just cut one of the tracks and run to an on/off switch.

Interestingly one track from the speaker goes to the unused switch. Maybe that could help your mod - ie, cut that pin's track on the other side of the PCB &/or insert pot or switch wires there. I was also thinking that being (possibly) a piezo buzzer its impedance may be hard to determine, or a pot/resistor may effect its operation. But it seems similar buzzers are also describes as electromagnetic types which typically have impedances from 16 to 80 Ohms, tho some may be higher (eg, 200 Ohms). I'd try a smallish resistor (10 to 100 Ohms) to see its effect and then guess what pot might suit (ie, 20, 100, 200 Ohm etc). I was also thinking a resistor or pot plus series resistor (to prevent a zero Ohm short) could be placed in parallel with the buzzer/speaker, but without knowing the driving circuit, that could be destructive to that circuit.

You will not damage the board if you use these simple board saving techniques. Put a little extra solder on both of the connections. Let it cool back down completely. Heat one of the connections till the solder is molten, gently lift that side of the driver till you feel it move. Do not try to remove that pin, we have to walk it out of the holes. Let it cool then heat the other connection till molten, then lift that side of the driver, it should move about twice as far as the first side moved. Let it cool and go to the other connection. Repeat till it is removed. If you have a solder sucker, now is the time you want to use it.

Yeah, solder suckers are great - especially when removing 64 pin leaded (QUIP) chips etc! Mind you, Mr I's walking technique is still often required... But for 2-pin devices I often don't bother with a sucker. Instead I heat one pin at a time whilst gently but firmly persuading that pin up/out a bit, then do the other, then back to the first. (And often burning finger tips in the process LOL!) The more it works out, the bigger each pull thru or walking step can be. Of course I am merely repeating Mr I's technique above... for what it's worth. If I can melt the full hole then I won't ad the initial solder, but sometimes adding solder is needed to melt the rest - tho I usually won't allow that first cool down except where needed (ie, it's already too hot). [Funny how that reminds me of dripping water into my ear so I can get existing trapped water out!] After a while you get quite good at it and get a good feel for what PCBs & tracks can tolerate - or more importantly - how many times they will tolerate it. But I have had self-destructo's - usually repeat work where it doesn't matter how careful you are, tracks simply lift or destruct. Then you replace each track manually with wire - and that's not fun for 0.5mm spaced SMD chips!