I posted this in the non-drivetrain section but will try here as well.

My batteries have gone dead when our '99 sits for long spells, which it's done a lot in the past year since we only use it for hauling stuff, pulling a horse trailer and getting loads of hay. We bought new batteries after our 2 year old batteries refused to be charged (now I find it may have been our charger's fault - ouch $$$!).

After putting in the new batteries, we drove the truck almost 400 miles in one day, and then I used the truck on another occasion to pull the trailer... that was a couple of weeks ago. Today I try to start the truck and they are stone cold dead!

On another forum I read some things about bad alts causing tranny problems as well as audio problems. I have noticed that our truck is hard to come out of first initially when cold. We also noticed weird audio interference a few times, a loud blaring sound.

A neighbor said it could be a bad diode in the alt allowing the charge to flow back out when the truck sits, but I read here that the diodes don't go bad often. I also saw a website that had inexpensive kits to do something with the brushes (??). Given these bits and pieces, can anyone say definitively what might be wrong?

Thanks for the help

 

Have your alternator tested at autozone free. I saw your other post and was going to say Alternator. Good Luck.

 

I would look at the alternator in this case. Get those batts charged ASAP because lead-acid batteries should not be left discharged for any period of time.
Once you get them charged, disconnect the neg leads while you troubleshoot the problem.
Also, make sure the batts and the mounts under them are clean.

 

One problem with early 24 valve trucks was with the seat belt timer module. These trucks have the seat belt built into the seat back and the timer was needed to free up the belt when the door was opened. If the timer gets screwy and keeps the belt free after the truck is shut off and the doors are closed for 20 or 30 minutes this may cause your batteries to drain. As a test, fully charge the batteries, close all doors but leave the windows open. Reaching into the window yank on the two front seat belts to see if they can be pulled from the seat back, they should be free. Go away for a ½ hour and try reaching through the window again to check if the belts are free, they should not pull out from the seat back. If they still are free there is a problem with the timer and this several amp draw from the batteries is the problem.

Good luck.

 

I had this problem on my 99 Quad Cab ... found out that the under seat connector to the Seat Belt control module was shorting out between two pins which left the accessories line energized constantly. Had to remove wire from connector and make a hard splice to eliminate short.

Fred