TM 5-6675-250-10
I
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
connecting power cables.
c. Report a defective ECU to the next higher level of maintenance.
2. TEST METER FAILS TO INDICATE PROPERLY (BETWEEN 22 AND 33 VDC)
Step 1. Check for a bad power source.
a. With the MODE SELECT switch position to SELF TEST and with
PWR ON indicator illuminated, place the TEST SELECT switch to
source voltage.
b. Depress the PRESS TO TEST switch: verify that the TEST METER
pointer is positioned between 22 and 33 VDC on the upper meter
scale. If the reading is less than 22 VDC, replace the battery or AC-
DC converter.
c. If AC-DC converter is being used, check for a defective converter
fuse.
d. Unscrew the cap on the fuse holder and remove the fuse.
e. Test fuse for continuity with an ohmmeter. Replace defective fuse.
f. Place the new fuse in cap of the fuse holder. Insert fuse in AC-DC
converter, press down, and turn the cap clockwise to secure the fuse
holder.
Step 2. Check for defective ECU.
a. Replace existing ECU with an ECU that is operable. If the system
operates correctly with the new ECU, this indicates the original ECU
was defective.
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