You could just unplug the buzzer and throw it in your toolbox but depending on the year/model
you might lose features you'd like to retain, such as door controlled cab lighting, headlights on
reminder or the ignition key light. here is an easy way of silencing the buzzer while retaining
all the original features

 

Great illustrations here, I've always wanted to do exactly this!

(But then I'm afraid the following day will be the one time i lock the keys inside.)

 

My 87 doesn't make a noise if I leave the keys in. I wonder if that box has been removed or is broken.
I do have a 87 base model long bed and I do mean base model!

 

Your base model did have the buzzer for the key. If your dome light is not working when opening the drivers door but works on the passenger side, the box is either disconnected or missing. It is located on the steering column.

 

Does anyone know if that buzzer sounds in the event of a loss of oil pressure or any other potentially catastrophic event? I hate the sound of the thing but I'm not touching it if it might alert me to a big-time problem even half a second sooner. I assumed it had some kind of function other than to remind you that your keys were in it due to the way it gives a test buzz before you crank it up. I'll kill mine the next time I'm in the column if it doesn't. There's 7 pins on that sucker. I'd like to see a pin-out on it.

 

Second that. LOL!

Key left in Ignition buzz: does not bother me and I want it for above reason, so I did not mess with my buzzer.
Seatbelt Reminder: I do not need/want so I just disconnected the seatbelt switch connector under the driver's seat.
Light reminder: I have a dlx that does not have light reminder so that was my first mod.

I do not think so (gotta check schematic), AND that is the problem with these vehicles. There's plenty of warning sound and light for little things, but no audible warnings for critical things... I started a thread for that HERE

 

I like the idea of that circuit you are talking about. I build in things like that into my log trucks at work. DOT requires low air buzzers and lights and the OEM systems are usually built into the main dash clusters which are not serviceable and very expensive to replace. I can build a DOT passable warning system for about $25. If you already have an idea as to where you would install the sensor in the cooling system, let me know and I'll see about posting a mod thread on it.

 

Awesome! More heads are better than one. I started a thread for Accurate Temp indicator with Audible Overheat Alarm here.

 

Thank you for taking time to cover this. That stupid door buzzer drives me crazy