BLACKOUT STOPLIGHT(S) DO NOT OPERATE (S/N YB6122 075 AND UP). (Cont) -725550309

TM 9-2330-385-14

Remove all jewelry such as rings, dog tags, bracelets, etc. If jewelry or tools contact positive electrical

circuits, a direct short may result. Damage to equipment, injury, or death to personnel may occur.

VOLTAGE TEST

(1) Set multimeter select switch to

volts dc.

(1.1)Disconnect wire 1678C/23 from

nonoperating LED composite light.

(2) Connect positive (+) multimeter lead

to wire 1678C.

(3) Connect negative (--) multimeter lead

to a known good ground.

(4) Turn on BLACKOUT LIGHTS selector

switch.

(5) While assistant fully applies brake

pedal, observe blackout stoplights.

(a) If 22 to 28 vdc are not present,

perform Steps (6) and (7) below

and repair wire 1678C/23 (see

schematic, Fig FO-1.1) or replace

composite light wire harness

(Para 4-30.1).

(b) If 22 to 28 vdc are present, perform

Steps (6) and (7) below and replace

LED composite light

(para 4-29).

(6) Release brake pedal.

(7) Turn off BLACKOUT LIGHTS selector

switch.

(8) Connect wire 1678C/23.

VOLTAGE TEST

(1) Disconnect 24 vdc (12 pin) cable from

front junction box connector MC15.

(2) Set multimeter select switch to volts DC.

(3) Connect positive (+) multimeter lead

to pin F on trailer end connector.

(4) Connect negative (--) multimeter lead

to pin D on trailer end connector.

(5) Turn on BLACKOUT LIGHTS selector

switch (TM 9-2320-364-10).

(6) While assistant fully applies brake

pedal, observe multimeter.

(a) If 22 to 28 vdc are not present,

perform Steps (7) and (8) below

and replace 24 vdc cable.

(b) If 22 to 28 vdc are present, perform

Steps (7) through (9) below and

repair wire 1678C (see schematic,

Fig FO-1.1) or replace trailer main

wire harness (Para 4-30.1)

(7) Release brake pedal.

(8) Turn off BLACKOUT LIGHTS selector

switch.

(9) Connect 24 vdc cable to front junction

box connector MC15.

4-118.49