Here is what my 2005 Owner's Manual says verbatim:
"NOTE: There is also an engine hour function. This indicates the total number of hours the engine has been running. To display the engine hours perform the following: Place the ignition in RUN, but do not start the engine. With the odometer value displayed, hold the trip button down for a period of 6 seconds. The odometer will change to trip value first, then it will display the engine hour value. The engine hours will be displayed for a period of 30 seconds until the ignition is turned off or the engine is started. "
Hope that clarifies it. When I tried RMalone's suggestion, I think the truck performed a self-test. Both the tach and speedo needles pegged out, then went back to zero. All lights lit up and then went off. Then, in the odometer/tripmeter window it said, "C C Code", then it said, "00 00". Then it went to the odometer reading.
Frederic