TM 5-6675-250-10
3-2. TROUBLESHOOTING - Continued
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
ELECTRONIC CONTROL UNIT (Continued)
b. Replace a defective ECU with a new one by disconnecting and con-
necting power cables.
c. Report a defective ECU to the next higher level of maintenance.
Step 3. 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.
GYROSCOPIC REFERENCE UNIT (GRU)
1. UNCAGED INDICATOR FAILS TO LIGHT WHEN CAGE-UNCAGED KNOB IS ROTATED TO
UNCAGED.
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.
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