what that migh be ECM,BCM,alternator

Hello every one;
I hope to find a diagnose to this problem I have, I have Buick 97 custom,
2 days ago while I’m driving the instrument panel lights up almost the engine stopped for 2-3 seconds then I heard the computer BCM clicking at same time,
Then it went back normal.
Then after 30 minutes of driving it completely stopped, and all dash board were lit,
I put back on park. I start it, it starts fine.
The day after/
I thought it could be a fuel pump, so I took off cap<pressure> go the gas line, then I pressed it to see if there is pressure. It is only when it’s running idling.
But when I got back after 5 minutes the car was not running and dashboard light came on
But the o’clock was on the correct time display
I went to work 20 miles driving was fine.
Tonight at work I let run but I sat inside. After 5 minutes it shuts off but all dashboard lights did not come on for 3 second. And then light came back on and the o’clock was reset. That means the car lost electric completely,
So I figured it could be alternator or ECM.
Cause 2 days back the elect gauge was reading almost 15 v running idle.
Tonight was reading 13+ v,

So what that might be, and where is BCM and ECM are located in the car, I used to have a caddy fleet wood BCM was behind glove compart and ECM was on firewall passenger side beneath dashboard.
thank you for your help

Here's an idea. Take the car into AutoZone, Wal-mart, Goodyear, Midas, or where ever and have them test your battery and alternator.

hello every one here is an update.
this morning i took off <-> batt cable to reset the ECM, so i took off also <+> , that was really bad. lots of white build up. so i metal brush that,then i start the car ,wow 30 minute no shutts off,gauge reading
14 1\2 v-15 v.
.i saved myself fuel pumb,ALT,batt,ECM,,if you know what i mean. :naughty:

i woulg give 30%of the cost of all these parts and labor to charity.thank you LORD.
thank you all

If it happens again within a year, I would be that you have a cracked in your battery around the terminal. Don't worry, the battery will fail soon enough.... right after it fills up with acid 3 more times and ruins your positive battery cable.