toyota pick up charging problems?

[Joey]

Okay so i have a 1991 toyota pick 22 RE best engine ever everything ran really good until one day i get the error code of the battery and the brake symbols. So then my battery died. no good. So i charged it and what do you know everything works no error code nothing. But now today after i washed my truck. once again i got the same message and the battery is dead as can be and it wont stay cherged after i charged it it just wont go away this time like last time. whats the problem here bad altinator? or a bad battery? the weird thing is these two problems occured when it was raining and when i just got done washing my truck. hmmmm i dont know anything helps guys thanks!

 

[JUANFRAN$$$]

How long has battery been in your truck~? Usually if the battery is going dead like that it is a dead cell in the battery or corroded terminals.usually on the battery but can also be at the starter.
When battery cables get corroded back enough the corrosion will also leach down the battery cables making it necessary to get new battery cables as well.
Something else to look for when it doing that when wet it could be your alternator brushes getting worn not making good contact. Had that happen before.
Some other things to look for is loose connections. They will be making good enough contact when dry but when wet the water acts like an insulator. Or the water could be causing it to go to ground (chassis ground)
Something else I have happen a lot is wiring connections at the starter getting covered with mud and causing a high resistance short to the chassis. Where I live we have a lot of iron ore clay dirt and you get into it when driving on dirt roads.