BATTERY

you need to check to see if there is an open circuit in the electrical system. Buy a tester to do this simple test.

The altinators go out on these. Hard to change but a mechanic can test to see if it is producing any voltage. You should be getting little over 14 volts. I would check there first as it takes time to go through the wiring.

Battery Drainage on my 1997 STS Alt putting out 14.3 when i first start then drops too 12.6 volts . New battery, New drive belt. All fuses good.????