GMC 2010 T-Series Owner's Manual page 71

4. Fully set the parking brake.
5. Shift the transmission to P (Park) or N (Neutral).
6. Idle the engine. If you used the idling control knob
to increase the engine speed, restore it all the way
to the left to reduce the engine speed.
7. If the vehicle has Power Take Off (PTO), turn the
PTO off. See Power Take-Off (PTO) on page 2 20.
8. Press the DPF switch on the instrument panel. See
Instrument Panel Overview on page 3 4. The
green DPF indicator light comes on, the exhaust
gas control valve operates, engine idle speed
automatically increases, and DPF manual cleaning
begins. Do not leave the vehicle unattended during
manual cleaning.
9. When both the green and the yellow or red DPF
indicator lights go off, manual cleaning is
completed. Manual cleaning is normally completed
in about 30 minutes.
Under certain operating conditions, manual cleaning
might not be able to be performed, even if the soot level
in the DPF requires cleaning. This can occur because
of low coolant temperature, low battery voltage, high
exhaust temperature or immediately after starting the
vehicle. When manual cleaning is requested and
coolant temperature is low, engine warm-up is started,
the green DPF indicator light will come on, the exhaust
gas control valve operates, and engine rpm increases to
help raise engine coolant temperature. When operating
conditions allow, cleaning will begin.
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