Got this yesterday morning, surprised we don't see it more often considering water under the battery caused it and it never rains here and the truck hasen't seen water in two weeks. Means theres an issue with the temp sensor under one of the batteries. Mine had moisture in it and brought the check engine light on. Dealer says they applied a little compressed air and reset the computer. This site was great in helping use the key on, off, on method to get the code and know what the code meant. When I told the service manager I knew what code it was pulling. he says,"who speced it out?". I think he was surprised when I told him I knew how bacause of the Diesal Truck Resource website. Knowledge is power, thanks guys!

 

Mine has had this code on and off for about 2 weeks. Do both batteries have a sensor under them?

 

Just the one on the driver's side.

 

What the heck is that sensor suposed to do?

 

From the service manual:

OPERATION
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 (ECM Diesel) 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°F.