TM 9-2320-361-20 Table 2-4. Electrical Troubleshooting (Contd). MALFUNCTION TEST OR INSPECTION CORRECTIVE ACTION 21. BLACKOUT HEADLAMP DOES NOT LIGHT Test 1. Test battery voltage at blackout drive light. Step 1. Turn main light switch lever to OFF position. Step 2. Disconnect lead 19 from blackout drive light. Step 3. Turn main light switch to BLACKOUT DRIVE position. Step 4. Check for battery voltage on contact end of lead 19. a. If battery voltage is present, go to test 2. b. If battery voltage is not present, go to malfunction 17, test 3, and check front wiring harness pin D. Test 2. Test continuity of filament in blackout drive light. Set multimeter to RX1 scale. Check continuity between frame ground and lead 19 attached to rear of blackout drive light. a. If continuity is not present, replace blackout drive lamp (para. 4-42). b. If continuity is present, check for corroded contacts at lamp and at lead 19 connection to front wiring harness. Reconnect lead 19. END OF TESTING! 2-106