any help would be appreciated

[alberto vazquez]

my 1998 gmc battery keeps dying and also overcharging i've replaced the alternator, battery, terminals, ground cable, and also positive cable going to the started. before the overcharging started the brown wire to the alternator wasn't getting any voltage, i've checked all the fuses and i couldn't find out why but now it's overcharging when i press the gas

[richard wysong]

If it is actually over charging it has a bad voltage regulator which is internal to the alternator so replace the alternator again and check the battery,  it is probably low on water if you can check it. Charging voltage should be between 13.5 & 15 volts . you may have a defective battery as well, disconnect it after a run and let it sit overnight, it should hold 12.6 volts, if not it's junk. You may want to check the wire from the alternator to +battery for voltage drop but nothing but a bad alternator can cause it to overcharge and it may be draining the battery if the diodes are bad

Edited January 21, 2023 by richard wysong

[richard wysong]

Use a DVOM meter to check it, do not rely on the dash gauges to give you accurate readings. WELCOME TO THE FORUM!

Edited January 21, 2023 by richard wysong