The truck uses the Malfunction Indicator Lamp (MIL) in the dash monitor panel to provide a means for determining if there are any Diagnostic Trouble Codes (DTC) stored in the ECM.
If you are successful in doing the accelerator pedal dance to set up the blink codes, you can count the blinks and figure out the 4 digit code number.
There is a diagnostic connector under the floor pan where a diagnostic reader can be connected to read stored codes and see "real time" problems.
If you are saying that there is not a Malfunction Indicator Lamp on the dash, how did you do the pedal dance you alluded to in your opening post?
The MIL should light up when you turn the key on and go out after the engine starts.
If the MIL does not burn when you turn the key on, that in itself is a defective condition, and must be fixed before doing anything else.
On your truck, look at the second light position to the right of the hour meter, the light that has an exclamation point (!) is the MIL.
That light should burn when the key is turned on and should go out after the engine is started.
If the light continues to burn after the engine starts, it is indicating that a defective condition still exists, or that a defective condition has caused a DTC to be stored in the ECM.
That light is what flashes to give you the blink codes for stored DTCs that the ECM may have.