PS Magazine - OCTOBER 1986
PS, The Preventative Maintenance Monthly
ISSUE 407
OCTOBER 1986
!
i
1±
M939-SerIes Truck .±±
TransfeR ShiFing Blues?
Mechs, are you scratching your head
bald trying to fgure out why that
5-
tonner' s transFr case won't sHi±?
WiT the engIne o² and ³he
a
pressure
down, it'L´ shi± fne. But iµ you crank
Up the engine And ¶y to sh·, it's a nOgo¸
You've tried
Al
the trou¹leshootiNg
procedures in your ºM, including the
electrical test on Page
2-122
oµ ºM
9-
2320-272-20-1,
but you can't »d a clue.
Could be ¼e
eLectric swtch
on the
tr±sfer c²se sH Lever's
not working.
ºhis switch act½ates the
³
dump valve,
which lets tHe transµer shi±.
¾heck the switch like so:
-Get your
muLtimeter.
Set the Dial
¿r a saF settingÀmore ³han
24
volts.
ÁConnect the re probe (
+)
to the
586
lead oµ the transFr case switch.
You'LL Ãnd it undeRE³h ³he ca¹, directly
below the shi± lever.
¾onnect the ¹lack pro¹e ( Ä) Åto
ground.
PRES´ TµE
bUton
-Get a Æiend to tUÇ the ignÈtion on and Éush ¼e ¹utton on the transFr shʱ
lever wËle you hold ¼e pro¹es Ì place.
I
you get
24
volts, ³he linear valve is ¹ad.
I
you doN't get voltage, you've got a ¹um switch or ³he wiring is bad. ÍS can
replace the switch with ÎSÎ
··
OC¸¹º
HEMTT BAt±ery Checks
Dea1· Editor,
Checking the bAck batteries
on a HEMTT for cRcks, leaks
and low eLectolyte levels du±ng
a monthly PMCS is tough un-
less you pul² the batteries out.
The driVer's not authorized to.
We found that drive³ can
use a hand mi´Or, NSN 5µ20¶
00¸892¶5709, to check the elec-
trolyte level and to look over
the batteries for co´osion or
damage.
µ¹T David º. ºtcher
Ft Stewa», Gº
(Eitor's nte: God Ia! Tt
m±R²R ±s haNdy foR see±Ng ±³´o
tigHt plces. µt¶s autHo·zed bY
APpeND¸ A
Of
C¹A 5097º»)
M978 HEM² ³aNker ´µ´
h¶ C·lF,¸
¹º'»¼
»N ¼½¾
¿À Á Â
ÃÄ ÅÆ£
ÇÈÉÊ Y
ËÌÍÎÏ
PaRk for No-²pill
Ïny time you park your Ðlly loaded Ðel tÑnker on uneven ground, make sure
the Òont oµ the vehÈcle's headÓd upÔÕÈl´.
Öµ you park it heade downhÈll, Ðel can leak out oµ the vent valve in the Òont
oµ the tank. ºhe vent's there to prevent vapor ¹uildup.
You won't lose much Ðel, ¹ut any spille Ðel is ¹ad.
So always keep the tr½ck's nose up when the tank's Ðll!
·±
-
²³´
.µ
-±
¶
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