first try this
cycle the power on and off 5 times
wait 10 seconds between each cycle of the power, see if codes clear after doing this.
If not then there may be a problem with the wiring in the harness to the platform control module. Check the connector where it plugs into the truck side and also the platform control module side.
These connectors do plug in and have a lock ring that has to be twisted to lock the connector into the plug so make sure it is completely inserted and locked into the connector properly.

If the cable and connectors check out ok visually and are connected properly then follow this procedure:

Manual suggests to remove the 9 pin platform control module connector from the side of the platform junction box and the P4 connector at the ground control module. Check continuity from the P4 connector, pin5 to junction box pin3 and P4, pin9 to junction box pin4. Is there continuity on these wires?
If no continuity repair wiring
If continuity then replace control module.