Electrical problems

Im putting this on the buick thread because the cars are similar I have a 90 olds trofeo, The battery won't charge, but the alternator is good as is its regulator, The cluster works when you turn on and off the lights, but then the backlight on the radio goes out, but the radio works, the display on the AC unit reads - - - and the climate control is non functional. , i have a constant 12.5 volts reading on the battery and it runs find for about 10 starts, then starts putting because the ecm doesn't have enough power for the injectors, And it will eventually die if you stop, i have a feeling it is just one really little stupid thing causeing all this. Any help would be madly appreciated

Sounds like a bad ground source,

Check your field wire to alternator.. it excites the coil and gets the alternator running. Some posts say the ECM excites it.. dont know for sure.

Good luck.