what is it? found it in the bottom of my tray in my 96 XJ while removing it in preparation for an alternator swap yesterday.

 

this must be it

Just as an add on, what the Jeep manual says:

The BTS is used to determine the battery temperature
and control battery charging rate. This temperature
data, along with data from monitored line
voltage, is used by the PCM to vary the battery
charging rate. System voltage will be higher at colder
temperatures and is gradually reduced at warmer
temperatures.
The PCM sends 5 volts to the sensor and is
grounded through the sensor return line. As temperature
increases, resistance in the sensor decreases
and the detection voltage at the PCM increases.
The BTS is also used for OBD II diagnostics. Certain
faults and OBD II monitors are either enabled
or disabled, depending upon BTS input (for example,
disable purge and enable Leak Detection Pump
(LDP) and O2 sensor heater tests). Most OBD II

monitors are disabled below 20 degrees F

 

Thanks for the info.

I was wondering the exact thing today.

As I replaced my battery.
I replaced the Optima red top that has been in there since 2005.
original style (Made in USA)

Went with a NAPA this time. Legend $90.00

 

The grands have a battery temp sensor maybe its that,If its not i have no clue what it does.

 

It's a temp sensor. Of the ECU sense the battery is too hot it will cease charging until its cooled down some.

 

And if you cut it off and toss it when replacing your battery tray with a fancy one from RuffStuff in order to re-work your inner fenders for more clearance for bigger tires, it will cause a CEL and the parts store guys will have no clue what that CEL means. You'll then have to do a couple of hours of research, identify what you need, and then find out they can get you the part for about $80. In other words, don't cut it off and chunk it!

 

Personal experience?

 

I actually have one I just brought inside today haha. Kept it as a spare thinking I would need it. Now going to list it on the 'Bay.

 

Absolutely....the best teacher, right?

 

Does anyone know what this is and how it would be fixed and the cost? Thank you ☺️

 

Your question is incomplete and hard to understand. You do not identify the year of your vehicle

The battery temp sensor is not just on 1999 models, my '96s have them

There is pictures of what looks like in this thread

Do you have the stock battery tray ?

whether you do or dont rummage around near or under the battery tray and see if the rubber plug covered temp sensor with its 2 wire harness is present, or if there is a cut harness

This item connects to the PCM, and works as described in the thread

its absence or failure with throw a code, and maybe CEL, as well as causing electrical charge issues

(your PCM wants to know what temp the battery is running at)

with respect to previous posters, (and possibly yourself) only an inattentive dick would cut it, hopefully its just jammed down out of the way

If its gone, you will have to get a new or used one, find the harness and fix it up. It should not be ignored