Why wont my battery hold a charge on my 1986 toyota pickup? my battery is 2 days old, and my alternater is about a month old. i think its gounding out some how but how do i pinpoint where?

if it wont start then the battery is dead from not charging is my guess. so now the question is why wont it charge. that's simple the alternator is not working properly and will need to be rebuilt or replaced. and they are not cheap. you will need to remove the alternator and take it out to get tested. my guess its going to need to be replaced. advance napa autozone and many other parts stores have the equipment to test it. then you need to charge the battery and it should start once you get it all back together. if you cant do the work. a shop will do it all and it will need to be towed if it wont run.

wow if your battery is that old i would get a different one but you can have the battery and alternator tested for free at a auto parts store they can tell you if its junk or not but thats why your having them problems when your alternater spins it charges the battery if the battery is no good it wont hold a charge and you car will die now it the alternater is bad it will not keep the battery charged and your car will die.

your alternater could be bad and not charging the battery, get it cranked then remove a battery cable. If it stays running, alternater is good if it dies alternater is bad

If the car runs until you turn it off and won't restart, the alternator is charging and the battery will not hold a charge. If it can't hold a charge, it will not be able to restart the car. If the car runs and then dies, the alternator isn't charging. The alternator may be wearing out and not be able to keep the car running and charge the battery. Chances are based upon your description of your problem (sounds like car runs until you shut it off and won't restart), it's a worn battery. If it's 5 or more years old, you probably need a new one. If you are not sure, test them. I think your battery is finished.

Check wires behind the alternator for corrosion, looseness and opens. Get shop manual and find the circuitry for the bulb and inspect it for opens . its been a few years but i believe you need B+ on both sides of the bulb to turn it off.

change or charge the battery and make sure you install the correct alternator capable of supplying the correct amps your car needs otherwise it wont charge correctly/ check your electrical wiring it must be grounded somewhere or the connection is incorrect thats why ur battery drains...

your alternater is shot bring it it to napa and order a new one its a common problem

First tell me why you don't think it's charging.
Because of the voltage reading you are getting at the battery terminals? The range you want is between 13.6v to 14.2v. The higher the voltage the lower the amps. and true the other way, the lower the voltage the higher the amps. If you get a reading of 13.6v or lower, the alt is nearing or at max output. An alt can only run at maximum for around fifteen minutes and it will start slinging solder from overheating. It's a good indication the battery is either totally dead or junk. Charging above 14.2 the alternater is running wide open and is only putting out high volts which will cause the battery to boil , in turn destroying it. This is a bad alternater. All alternaters have integrated voltage regulater with the exception of ver few of the earlier ones. You cannot test an alternater by removing a battery cable to see if the engine keeps running without taking great risk of damaging the alt, regulator. So tell me why you feel it isn't charging. Remember an alt is not made to charge dead batteries. Their sole function is to maintain the battery charge. Without a battery, the alt won't last 10 seconds.
Hope to hear from you and good luck.

check alternater output....

yes, you must remove the top panel on the fuse block the 80 amp fuse is bolted to the the fuse panel, hope this helps if not get back to me as i strive to be the best please rate my fix Thanks Ray