Well this WAS not fun. (trouble starting/running truck)

[RSTahoe99]

so you charged the batt. put it back in the truck and now think its on its last leg? what happened to determine that? If you batt. is charged start the truck and unhook you negative batt. cable if the truck soon dies, your alternator is bad. The battery could be fine, just that your alt. is not recharging it.

Plus you can pull the caps off of your batt and check out the cells to see if they are low. If they are fill them with DISTILLED WATER ONLY and charge it, this might buy u another year on your batt.

 

[jcro61]

I was told that if you did this you could damage a good alternator in the process.

what you can actually damage is the ecm

 

[dustin83]

Last week I finally replaced the battery. Last week the battery would barely be able to fire the engine up, and the battery had only sat for maybe 12 hours. Replaced the battery and now it fires right up no matter how long it sits.