Looked at a couple of used trucks this week. Some of them had a "Light Load" button, below the radio. If it had a read sliding window, this button was right beside that. What is this for?

 

Cargo light maybe?

 

Just found this using Google, from another thread on this subject here:

With the "light load" button illuminated, the TPMS will trigger an alarm when the rear tire pressure falls below 45psi. With the "light load" button NOT illuminated, the TPMS will trigger an alarm when the rear tire pressure falls below 60psi. The "light load" button does not affect the trigger point of the front tires (60psi always).

The TPMS/light load functions on these 08+ 2500 trucks are a PITA. They are finicky and sometimes will not function properly with no cause. There have been rumors that the pressure with which the TPMS triggers an alarm can be adjusted via the StarScan tool at the dealership, but I have yet to find a dealership with a tech who knows how to perform this function. It is the TPMS function alone that makes me wish, when I bought my '08 2500, I would have instead ordered a 3500 and waited the extra 6 weeks for the truck to be delivered (3500 model trucks, regardless of wheel base or SRW/DRW, are not required and are thus not equipped with TPMS).

 

Light load pressure can be adjusted. A friend with an 08 2500 had his tuned down to 30psi at the dlr on all 4 wheels so he could air down in the winter without having the TPMS light come on.

 

If you had your tires aired to 80, then the TPMS light should never come on no matter if the button is pushed in or not.