Table 4-1. Unit Troubleshooting Chart (cont).
ELECTRICAL SYSTEM (cont).
5. SERVICE STOPLIGHTS AND TAILLIGHTS
Continued from step C
D. Connect IVC to dolly set distribution box. Turn
towing vehicle master switch OFF. Disconnect
wires 489-21 from both composite taillight as-
semblies. Disconnect wire 461-22 from left
composite taillight assembly and wire 460-22
from tight composite taillight assembly. Turn
towing vehicle master switch ON. Engage
towing vehicle service brake. Alternately place
red lead of multimeter in center of all discon-
nected wires and ground black lead to vehicle
frame. ensuring metal-to-metal contact.
IS BATTERY VOLTAGE PRESENT AT ALL
wiring harness (para 4-25).
E. Turn towing vehicle master switch ON. Re-
move taillight cover from taillight assembly, and
remove inoperative light bulb(s) from sccket(s).
Place multimeter red lead on center contact in
light socket assembly. Do not let red lead touch
side of socket. Ground black lead to socket
base, ensuring metal-to-metal contact.
IS BATTERY VOLTAGE PRESENT?
Replace composite stoplight-
taillight assembly (para 4-24).
F. Perform continuity test on light bulb by placing
red lead of multimeter on bulb base center and
black lead on bulb base exterior.
IS CONTINUITY PRESENT?