Dash Warning Lights / Alarm

A little background - - - A few weeks ago, I was tinkering around trying to get my dash warning lights and alarm working. I got the volt meter out and realized the alarm circuit board under the dash wasn't getting any power. I followed the wires back with help from a post on here detailing what each wire is and how to change the pots on the board. After following the 12v hot wire back to the ignition switch, I found that it was connected to the starter post on the ignition switch, not the 'ignition on' post. Once I changed this around, I was proud of myself thinking it would now begin to function again. As soon as I turned the key, I got the alarm buzz for the no oil pressure - or so I thought, but as soon as I cranked up the engine, it never turned off even though I was carrying about 70 PSI. All three alarm lights were lit up, too. I went to grab the alarm circuit board to start tinkering with the pots to just see what I could do and I noticed the board was HOT! to the touch. I turned each pot to both directions fully and none of the lights shut off. So I gave up on that project.

My question is this - I noticed on the engine there are two separate senders for both the water temp and the oil pressure. The two water temp senders are on either side of the water neck on the manifold. Only one has a wire connected - to run the gauge on the dash. There are two oil pressure senders on a t-fitting coming out of the side of the block. Only one is hooked up. Can I just run a wire from each of the warning lights on the dash to the respective unused sender for the oil pressure and water temp? I don't understand why we need to have that alarm circuit board in the first place. Couldn't I just buy a sending unit for the water that will ground at say 190 - 200 degrees and turn on the light? Or get an oil pressure sender that will ground at less than 10 psi or something and turn on the light? Couldn't I even wire the alarm to this same ground wire from the sender?

That's my big question... why do we need the alarm module? Is it only for the volts? I really don't care too much about the volts. Worst case is I could be stranded on the lake with no power right? I really just care about water temp and oil pressure.

Let me know if I'm headed in the wrong direction here...

Thanks!!

You could try to reinvent the system if you wanted, it's possible. The factory system doesn't just ground signals out. It uses a reference voltage and IC to indicate the warning light and buzzer. It's not a bad system, and very simple in terms of electronics. There just aren't many shops that know much about it or how to fix it without replacing the module.