PS Magazine - TB 43-PS-666
PS, The Preventative Maintenance Monthly
ISSUE 666
MAY 2008
16
PS 666
MAY 08
Dear Half-Mast,
Our unit mechanics disconnected
the CTIS system on the up-armored
M939-series 5-ton trucks and
increased the tire pressure to
70 PSI manually.
Several mechanics removed and
discarded the CTIS components,
including the hoses and fittings.
With the new ECU box that’s shown
on Pages 14 and 15 of PS 651
(Feb 07), should these components
be reinstalled? The answer changes
depending on whom you ask. Some
say the vehicle is deadlined without
the CTIS, some say it is not.
What’s the straight story?
Mr. P.V.R.
Camp Arifjan, Kuwait
On M939A2’s equipped with the original CTIS ECU, the tires are automatically
inflated to 60 psi on non-wrecker models and 80 psi on wrecker models when
the vehicle’s highway mode is selected. On up-armored 5-tonners, the CTIS is
disconnected, valve cores are installed, and the tires are inflated to 70 psi on non-
wrecker models and 90 psi for wrecker models.
If any of the CTIS components are faulty, the non-armored truck with CTIS still
connected becomes NMC only while the vehicle is being serviced during its semi-
annual/annual inspection, also shown in Para 2-12 in Table 2-1 of TM 9-2320-272-
24-1.
When the CTIS is disconnected on an up-armored 5-ton, there is no requirement
to restore the CTIS to an operable condition. Leave it disabled. A disabled CTIS
does not
make the truck NMC during scheduled or unscheduled maintenance.
You’ll Fnd this same info spelled out in TACOM SOUM 06-019. (See page 57 of
this issue for more information.)
Remember, mechanics should not remove CTIS
components or toss them out.
TACOM LCMC recommends taking a close look at the SOUMs that address this
issue—01-013 and 06-019. The headshed is also in the process of changing the
CTIS components so mechanics can reactivate a disabled CTIS with
new hardware. The new setup allows for higher tire pressures.
M939-Series
5-Ton Trucks…
Mr. P.V.R.,
Here’s the
scoop…
With your
commander’s
approval,
mechanics can
disconnect
(or
neutralize), but
not
remove,
the
CTIS on M939A2-
series trucks.
The vehicle is
not deadlined.
You’ll find this
info in TACOM
SOUM 01-013. Here
are some other
things you need
to keep in mind.
What do we do with these
CTIS components?
I figure we
just throw
‘em away.
You’re only
supposed to
DiSCONNECT
my CTIS.
..
not
REMOVE it!
and Tire Pressure Info
CTIS NMC Criteria
You
can’t
do
that!
666.16-17.indd
1-2
3/24/08
3:43:05 PM
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