Cessna Skyhawk 172N Pilot Operating Handbook page 242

WARM UP AND FADEC-TEST
(1) Let the engine warm up about 2 minutes at 890 RPM.
(2) Increase RPM to 1,400 until Oil Temperature 50°C, Coolant
Temperature 60°C.
(3) Thrust Lever - IDLE
(4) "Engine Master" - OFF
(5) Area Aircraft / Propeller - CLEAR
(6) "Engine Master" - ON, wait until the Glow Control light
extinguishes
(7) Starter - ON, keep starter engaged until min. 500rpm
Release when engine starts, leave Thrust Lever in idle
(8) Ammeter - CHECK for positive charging current
(9) Voltmeter - CHECK for green range
(10) FADEC and propeller adjustment function check:
a) Thrust Lever - IDLE (both FADEC lights should be
OFF).
b) FADEC Test Button - PRESS and HOLD button for
entire test.
c) Both FADEC lights - ON, RPM increases
.
WARNING:
d) The FADEC automatically switches to B-component
(only FADEC B light is ON)
e) The propeller control is excited, RPM decreases
f) The FADEC automatically switches to channel A
(only FADEC A light is ON), RPM increases
g) The propeller control is excited, RPM decreases
h) FADEC A light goes OFF, idle RPM is reached, the test
is completed.
i) FADEC Test Button - RELEASE
(11) Force B Switch - switch to FADEC B
(12) Engine - check running without a change
(13) Force B Switch - switch back to Automatic
Page 4-12
Issue 2
Revision 7, Jan. 2018
Reims/Cessna (F) 172 N&P
If the FADEC lights do not come on at this
point, it means that the test procedure has
failed and take off should not be attempted.
Supplement POH
with TAE 125-02-114