TM 5-6675-250-10
3-2. TROUBLESHOOTING - Continued
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
GYROSCOPIC REFERENCE UNIT (GRU) (Continued)
b. Replace a defective GRU with a new one by disconnecting and
connecting power cables.
c. Report a defective GRU to the next higher level of maintenance.
Step 2.
Check for a defective ECU.
a. Replace existing ECU with a ECU that is operable. If the system oper-
ates correctly with the new ECU, this indicates the original ECU was
defective.
b. Replace a defective ECU with a new one by disconnecting and
connecting power cables.
c. Report a defective ECU to the next higher level of maintenance.
2. UNCAGED INDICATOR FAILS TO GO OUT WHEN CAGED-UNCAGED KNOB IS ROTATED TO CAGE.
Step 1.
Check for a defective GRU.
a. Replace existing GRU with a GRU that is operable. If the system
operates correctly with the new GRU, this indicates the original GRU
was defective.
b. Replace a defective GRU with a new one by disconnecting and
connecting power cables.
c. Report a defective GRU to the next higher level of maintenance.
Step 2. Check for a defective ECU.
Replace existing ECU with a ECU that is operable. If the system oper-
a.
ates correctly with the new ECU, this indicates the original ECU was
defective.
3-11
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