TM 9-2320-361-20 Table 2-4. Electrical Troubleshooting (Contd). MALFUNCTION TEST OR INSPECTION CORRECTIVE ACTION 23. BLACKOUT TAILLIGHT LAMP DOES NOT LIGHT Test 1. Test battery voltage at rear composite light. Step 1. Turn main light switch to OFF position. Step 2. Disconnect lead 24 at rear composite light on side of vehicle where blackout taillight has failed. Step 3. Turn main light switch to BLACKOUT MARKER or BLACKOUT DRIVE positions. Step 4. Check for battery voltage at contact end of lead 24. 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 E. Test 2. Test continuity of filament in blackout taillight lamp. Check continuity between lead 24 attached to rear composite light and frame ground. a. b. If continuity is not present, replace blackout taillight lamp (para. 4-46). If continuity is present, check for corroded contacts at lamp and on lead 24 connection to rear wiring harness. Reconnect lead 24. 2-108