Today, I had to disconnect my battery, remove, and clean it. I notice a round tab at the bottom of tray. I lift it up and it was a sensor connected to it, why would a sensor be at the bottom of a battery tray? Does any one have any idea what that is? If no one knows I'll have to take a picture and post it.

 

Do you have an aftermarket alarm system? Sometimes alarm systems will come with a pressure sensor underneath the battery so the alarm goes off if the battery is removed (obviously the alarm has a backup battery)

 

My guess is it is a battery temperature sensor.

 

yep, batt temp sensor

 

No aftermrket alarm, just the one that came with the truck. Battery temp sensor thats what it looks like. I didnt think about that thanks

 

+3 on the battery temp sensor.
The PCM uses this temp to work out how much the battery is charging.
Al.

 

I like threads like these... something i'd never even thought about. Never knew it was there. Now i've learned something today...and its not even 5am yet!! haha

 

Wow, that is good I could've figured it no better. The PCM measures how much the battery is charging. This is why I love this site! You get better answers and options than the dealership. And you don't have to sit on the phone forever nor wait around the shop twindling your thumbs.

 

i have installed alot of alarms in my day and non of them have a battery pressure switch, only wires that go under the hood are siren hot, hood pin, and maybe the starter kill on a newer chevy.

 

Actually Chrysler is pretty advanced when it comes to battery charging / maintenance. They've had this sensor since at least '99 on Jeeps.