Ammeter Shows Zero Current All Phases Of The Timer Cycle; Ammeter Shows Normal Current Part Of Cycle, Zero Current Rest Of Cycle - Piper PA-44-180 SEMINOLE Maintenance Manual

CHART 3004. TROUBLESHOOTING (PROPELLER DEICER SYSTEM)
Trouble
Ammeter shows zero current
all phases of the timer
cycle.
Ammeter shows normal
current part of cycle,
zero current rest of
cycle.
PIPER AIRCRAFT
PA - 4 4 - 1 8 0 / 1 8 0 T
AIRPLANE MAINTENANCE MANUAL
Cause
Tripped circuit breaker
switch.
No power from airplane.
Circuit breaker or switch
faulty.
Ammeter faulty. (If some
or all deicers heat with
ammeter at zero, replace
the ammeter.)
Open ammeter to timer.
Open in wiring between
timer and brush block
assembly.
2E3
Remedy
Locate and correct
short before setting
circuit breaker.
If no voltage into switch,
locate and correct open.
If no voltage at C/B output
with voltage at input and
C/B does not reset, replace
C/B. If voltage is OK at output,
check switch in same
manner. If voltage is OK at
switch output, go to next
step.
Test for voltage up to
and out of ammeter. If
low output and input satisfactory,
replace ammeter.
If no voltage to ammeter,
locate and fix open between
switch and ammeter.
Disconnect harness at
timer and check Voltage
at Pin B (of harness) to
ground. If none, locate
and correct open.
Use heat test to find
deicers not heating and
test for voltage on that
contact of wire harness
plug. (At brush block
assembly.) If zero after
1 minute, locate and
fix open in wiring from
timer to wire harness
plug .
Revised: May 15, 1989
3 0 - 6 2 - 0 0
Page 30-23