Thanks to Jdonoghue’s recent thread on, What’s inside the Cummins ECU... peeling back some of the mystery, it occurred to me there might be a problem using programmers on the Cummins engine.

After looking at the construction of the ECM case that gets bolted to the engine block, I realized the reason for placing the circuit board on the thin metal cover. It is to help with cooling. The thin metal limits heat conduction from the block and allows outside air to draw heat away. Most of the components inside are rated for a maximum operating temperature of only 85*C (185*F) and the chipmaker will only guarantee proper operation at or below that temperature. I then remembered reading several past posts on the forums, of ECMs dieing after a dealer re-flash. This might be explained by having the ECM re-flashed on a hot day with a hot engine. The temperature could easily be way above 85*C. Most chip temperature specifications allow some latitude for an over temperature condition but not a 100% of the chips will work above the maximum operating temperature.

Any one who uses a programming box to change settings in the flash memory, using the under dash OBDII port might want to do it on a cool engine. The memory could be corrupted at high temperatures and that’s no fun.

Food for thought.

 

Hey man I got a snake.

 

you actually brought up a good point!

 

I guess my post was a little “over the top” but I will no longer change the levels using my Smarty with a hot engine.