TM 9-2320-289-20Table 2-4. Electrical Troubleshooting (Con’t)MALFUNCTIONTEST OR INSPECTIONCORRECTIVE ACTION11. VOLTMETER INOPERATIVE (Ml 010 AND M1028 WITH 200 amp SYSTEM)Step 1.Check 20 amp ignition fuse and 10 amp/28 v (voltmeter) fuse. (Seeparagraph 4-12)Replace fuse if burned out.Step 2.Remove voltmeterrelay. (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 tofuse block. (See wiring diagram F-6) If circuit is good, replace voltmeter. (Seeparagraph 4-9)12. VOLTMETER IN RED (OVERCHARGE) ZONE AT ALL TIMES (M1010 AND M1028 WITH 200 ampSYSTEM)Step 1.Start engine, bring to full operating temperature, then shut off. Remove 20 ampengine control fuse. (See paragraph 4-12) Start engine and check voltage at loweralternator positive (+) terminal.If voltage is over 29.1, replace lower alternator voltage regulator. (Seeparagraph 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 ampSYSTEM)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 ampengine control fuse. (See paragraph 4-12) Start engine and check voltage at loweralternator positive (+) terminal.If voltage is below 28.5, trace circuit from lower alternator “IGN” terminal tobulkhead 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 (seeparagraph 4-4) and ensure that adjustment screw is in “Hl” position. Ifadjustment screw is in “Hl” position and voltage is still below 28.5, replacelower alternator voltage regulator. If voltage is still below 28.5, replace loweralternator. (See paragraph 4-3) If voltage is still below 28.5, notify yoursupervisor.Change 22-61
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