(a) Bias mode, pin f (pre-amp output): This
(2) If a malfunction occurs, monitor the signals
should be an ac signal riding on + 9 vdc component.
in that column, following the numerical order shown,
If there is no ac signal, this indicates that the failure
(3) Note in order, all signals which are not
i s in the GRU. To verify this condition, open the
toggle switch for pin f on the breakout box and check
(4) Repeat steps (1) and (2) for all remaining
for the signal at the GRU terminal. If the signal is
c o l u m n s applicable to the signal. In this manner all
p r e s e n t , the failure is in the ECU.
failures will be noted and checked in more than one
(b) F u s e i n t h e E C U b l o w s e a c h t i m e t h e
m o d e of operation.
pendulum is uncaged: Open the toggle switch for pin
( 5 ) The first failure in each column indicates
L on the breakout box. If the fuse does not blow, the
w h i c h unit is malfunctioning. Conditions noted in
uncage switch is a possible failure. Additional tests
t h e failure column indicate a failure in the GRU or
o f signal associated with the uncaging circuit will
isolate the fault.
(6) Examples of failure analysis are provided in