PS Magazine - TB 43-PS-736

PS, The Preventative Maintenance Monthly

ISSUE 736

MARCH 2014
PS Magazine - TB 43-PS-736 - Page 4 of 33
Disconnect to Protect
De-icer
modules on
up-armored
HMMWVs should
be disconnected.
Mechanics,
disconnect the
three power and
ground cables—
wires 29D, 57C
and 440A—to
reduce the risk
of damage to
equipment
or injury.
5
PS 736
MAR 14
I
f you haven’t already heard, mechanics, there’s a problem with the windshield de-
icer module, NSN 2540-01-560-2062, that may be installed on some up-armored
HMMWVs. The culprit is a short that can result in overheating, smoke and maybe
even a Fre.
The short is likely caused by a transient voltage surge that occurs if the HMMWV
is improperly slave started or operated with low batteries. This can happen even if the
de-icer is
not
being used because the module is connected to DC power whenever the
vehicle is running.
And keep all four 441 leads that run from the de-icer module to the windshield
connected. Get de-icer disconnection procedures at:
?t=gpm&f=HMMWVDeiceDisProc.pdf
Reconnect to De-ice
Whenever windshield de-icing is needed to complete a mission, it’s OK for
mechanics to reconnect power leads to the de-icer module. Just pay close attention
for signs of overheating.
If overheating occurs, make sure the three power and ground cables from the de-
icer module are immediately disconnected. Mechanics should also disconnect them
as soon as you’re done de-icing.
Slave Starting Solution
Improper slave starting can create this short, but keeping batteries charged and
properly slave starting your HMMWV can prevent it. ±or correct slave starting
procedures, take a look at TACOM’s maintenance action message, MA 11-041,
Slave
Starting Procedures for High Mobility Multipurpose Wheeled Vehicle (HMMWV)
Family Of Vehicles.
It’s available at:
Future Fix
An upgraded de-icer module is in the works. We’ll tell you when a replacement
is available.
Need more info? Contact TACOM’s Nathaniel Zachary at DSN 786-4306, 586-
282-4306 or email:
nathaniel.j.zachary.civ@mail.mil
You can also contact TACOM’s David Stein at DSN 786-8398, 586-282-8398 or
email:
david.a.stein6.civ@mail.mil
Up-armored
HMMWV…
Disconnect to
Protect Windshield De-Icer
DiscOnNecT wires
29d, 5
7
C and 44oA.
an internal short can
cause the module to…
…or…
burn
melt!
why are you
Smoking?
it’s my
de-iCer!
but your
de-icer’s
not
on!
I
know!
De-icer
module
Wire 29D
Wire 57C
Wire
440A
736 04-05.indd
1-2
1/28/14
2:48 PM
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