I was trying to start my truck, and when i would crank it the starter would sound like it was not going very fast or powerful and it would steadily get weaker and i could here switches and solenoids or something clicking on the right side of the truck. I tested the battery voltage and it was 6v so i charged it and then checked it again and it was 6v. So i took the battery out and it was at 11.96v, but when i hooked it up it wasn't. So i cleaned the battery cables and posts and it was at 11v but now the power doesn't even seem to be coming on. i pulled codes the other day and it seemed fine but ow it is doing this.

 

If you're only pulling 6v under load on that battery and it won't charge, then the battery is dead.

 

Ok thats what i figured, thanks ill get a new battery.

 

Lets think about this some more. If the battery measured 11 volts across the posts, but measured 6 volts across the cable clamps, you also seem to have a high resistance connection with the battery cables, as well as a discharged battery as has been said. 11 volts = about a 10% state of charge. A high resistance connection to the charger will prevent it, or the vehicles alternator from properly charging/recharging the battery.
So, maybe remove the cable clamps & connect your charger directly to the battery posts if you haven't already done this when you recharged it.
Remove the cell caps & check electrolyte level & top up with distilled water as needed & recharge the battery at a slow rate, say around 4-6 amps. With this low state of charge Don't set it outside in below freezing temps.

Once you get the battery state of charge sorted out, using your multimeter, perform end to end voltage drop tests on on both battery cables, as outlined in the last post in battery tutorial thread atop this forums thread index page. If the cables fail the voltage drop tests, replace them, as they will prevent the alternator from properly recharging the battery & will give the engine & its electrical components load, below spec operating voltage & they won't appreciate that.

If you have to replace the battery, or just recharge the old one, be sure to check the the electrical system output under load, by turning the lights & blower motor to High speed, to make sure the alternator, battery, battery cables & their connections can handle the electrical load without out of spec voltage drop. The unloaded idle voltage at the battery posts should be about 13.2 volts & should climb to maybe 14-14.5 volts at say 2500 rpm. Under load with the lights & blower on, it may be a little lower.

If you don't have a multimeter to perform the tests, run this puppy by your favorite autoparts store & ask for their test guru to run their no cost electrical system check-up, via their portable electrical system tester. Properly used, it can check the soundness of the battery, alternator, cables & their connections.

More thoughts for consideration, let us know how it goes.

 

Ok i tried charging the battery again and tested the voltage but it dropped when under a load and the truck wouldnt crank so i replaced it, and it is doing fine now.

 

OK, good feedback, but consider having the electrical system tested to make sure the alternator, cables & connections are sound, such that they can take proper care of the new battery. An old battery can put an unusual work load on the alternator & its voltage regulator, so make sure they're still up to the task.