TM 9-2320-289-20
Table 2-4. Electrical Troubleshooting (Con’t)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
11. VOLTMETER INOPERATIVE (Ml 010 AND M1028 WITH 200 amp SYSTEM)
Step 1.
Check 20 amp ignition fuse and 10 amp/28 v (voltmeter) fuse. (See
paragraph 4-12)
Replace fuse if burned out.
Step 2.
Remove voltmeter relay. (See paragraph 4-9) Start engine. Using jumper wire,
connect brown lead terminal and brown/red lead terminal.
If voltmeter reads in green zone, replace relay.
If voltmeter does not read in green zone, trace circuit from bus bar ground to
fuse block. (See wiring diagram F-6) If circuit is good, replace voltmeter. (See
paragraph 4-9)
12. VOLTMETER IN RED (OVERCHARGE) ZONE AT ALL TIMES (M1010 AND M1028 WITH 200 amp
SYSTEM)
Step 1.
Start engine, bring to full operating temperature, then shut off. Remove 20 amp
engine control fuse. (See paragraph 4-12) Start engine and check voltage at lower
alternator positive (+) terminal.
If voltage is over 29.1, replace lower alternator voltage regulator. (See
paragraph 4-4)
If voltage is between 28.5 and 29.1, replace voltmeter. (See paragraph 4-9)
13. VOLTMETER IN YELLOW (UNDERCHARGE) ZONE (Ml 010 AND Ml 028 WITH 200 amp
SYSTEM)
Step 1.
Check alternator belts for looseness or damage. (See paragraph 4-3)
Step 2.
Start engine, bring to full operating temperature, then shut off. Remove 20 amp
engine control fuse. (See paragraph 4-12) Start engine and check voltage at lower
alternator positive (+) terminal.
If voltage is below 28.5, trace circuit from lower alternator “IGN” terminal to
bulkhead connector. (See wiring diagram F-10) If voltage is still below 28.5,
perform step 3.
If voltage is between 28.5 and 29.1, replace voltmeter. (See paragraph 4-9)
Step 3.
Install 20 amp engine control fuse. Check voltage at lower alternator positive (+)
terminal.
If voltage is below 28.5, remove lower alternator voltage regulator (see
paragraph 4-4) and ensure that adjustment screw is in “Hl” position. If
adjustment screw is in “Hl” position and voltage is still below 28.5, replace
lower alternator voltage regulator. If voltage is still below 28.5, replace lower
alternator. (See paragraph 4-3) If voltage is still below 28.5, notify your
supervisor.
Change 2
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