Disassembly Procedure

Remove the DEF supply pump module insulators.
Note the routing of the DEF wiring jumper harness,

Fig 1: Fuel Pump, Fuel Pressure Sensor, And Fuel Reverting Valve

Courtesy of GENERAL MOTORS COMPANY

NOTE:

After disconnecting electrical connections, protect connectors by wrapping with a suitable plastic bag and rubber band prior to removing DEF module to prevent dripping reductant fluid into connector cavities.

Disconnect the DEF wiring jumper harness connectors from the pump (1), pressure sensor (2), and reverting valve (3).
Fig 2: DEF Supply Pump Module
Courtesy of GENERAL MOTORS COMPANY

Remove the 3 DEF supply pump module retaining bolts (1).
Carefully lift the DEF supply pump module (2) to remove from the reservoir cover.

Fig 3: Reservoir Cover Supply Pump Ports

Courtesy of GENERAL MOTORS COMPANY

Carefully remove & discard the supply pump to reservoir cover o-ring seals (1). The seals will typically remain in the reservoir cover, but may be on the underside of the supply pump.
Wipe away any dried DEF crystallization residue from the reservoir cover supply pump ports (2).