I have what I think is a weird one. Got a Dash Command Scanner to keep an eye on things while driving. While towing this weekend things just got plain weird. Pulling Heavy over 8000 lbs I used the Tow Haul mode and the truck preformed great. 6 Hour drive through moderately hilled 2 lane highway.
My ECT (Coolant temp) got as low as 131. When this low my egr would read 0% over the next 1-5 min my temps would climb back to 160 where my egr would read somewhere around 5-17% Then the ect would slowly drop back to 131 then the egr would close and this cycle continued. Worse of all my oil (eot) stayed consistently around 239-246. The engine ran strong all day. When I dropped the trailer and headed home I turned off my tow haul and the temps were consistently as follows:
also the trans temp never got above 177
Why would my ect be hotter when in tow haul?
Does the tow haul mode keep coolant colder to help cool trans?