Attention: TDR Forum Junkies 
I'm surprised and a little disappointed to learn that the most recent Gen III trucks have programs to override the driver's desires and turn the brake off or on when the ECM determines it is right. It is true, as stated above, that there is no good reason to leave the brake closed when idling at a traffic light. However, when the driver is allowed to decide the brake can be activated to keep combustion chamber temperatures up during long idle periods in extreme cold weather. I don't know if the 170 degree engine coolant set point would permit that or not. My guess is it would cycle around 170 degrees and turn the brake off and on allowing combustion chamber temperatures to rise and fall. I have allowed my Gen II truck to idle overnight on more than one occasion when ambient temperatures were in the teens and I was forced to sleep in the truck. With the exhaust brake closed EGT remains at 400 degrees. I don't have scientific evidence to back up my theory but since 300 degrees is the generally accepted point at which shut downs are recommended I've assumed that 400 degrees and the load provided by backpressure is probably sufficient to prevent unburned fuel washing cylinder walls and buildup on valve stems etc. Apparently the driver can no longer use the exhaust brake for this purpose on the new trucks. I may decide to install my MOPAR/Jacobs brake with a separate 12 volt source isolated from the ECM.
Comments are invited.
Harvey
Comments are invited.
Harvey
