TM 9-2320-361-20 Table 2-4. Electrical Troubleshooting (Contd). MALFUNCTION TEST OR INSPECTION CORRECTIVE ACTION 24. BLACKOUT STOPLIGHT LAMP DOES NOT LIGHT Test 1. Test for battery voltage at rear composite light. Step 1. Step 2. Step 3. Step 4. Turn main light switch to OFF position. Disconnect lead 23 at rear composite light on side of vehicle where blackout stoplight has failed. Turn main light switch to BLACKOUT MARKER or BLACKOUT DRIVE positions. Depress brake pedal and check for battery voltage on contact end of lead 23. 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 N. Test 2. Test continuity of filament in blackout stoplight lamp. Check continuity between lead 23 attached to rear composite light and frame ground. a. If continuity is not present, replace blackout taillight lamp (para. 4-46). b. If continuity is present, check for corroded contacts at lamp and on lead 23 connection to rear wiring harness. Reconnect lead 23. 2-109