PS Magazine - JULY 1986
PS, The Preventative Maintenance Monthly
ISSUE 404
JULY 1986
M915-Series/M915A1 .±²
Ignition Switch Snafu
M9
I
5 mechs, there's a supply snafu
when it comes to ordering ignition
switCh, NSN 29±0-01-09±-9134. You
may get one that won't work on your
truck.
The switch you need, PN 31-164²
comes witH the spade lugs to connect
to tHe wiring harness.
PN 3³´³22
PN 3³·³64
WRONG
RIGHT
If you get a switch witH threaded
poles, it's tHe wrong switch. It won't
woRk.
Send in an SF 364
³eport
of
Discrepancy.
You don't need a whole new switch
to replace only tHe lock cylinder.
The cylinder comes under NSN
±540-01-155-360 l and inclUdes tWo
keys.
To replace a lock cylinder, take
out tHe switch assembly. Push a
small puncH in the hOle on tHe si
d
e of
the switch assembly and tip tHe switcH
down so the lock cyl´nder slides out.
PusH tHe replaµement cylinder in
until it clicks. THen put the switch
assembly back in the truck.
¶se nut, NSN 5310-01-179·4±54,
to Hold tHe switcH assembly in the
dasH.
20
JULY 86
M151µSeries trucks .
.¶
Don't Cross the SpaRk!
-
_
d
I
d
There's some confusion about how to hook up tHe ignition coil on the
M 151¸series trUck.
The right way gives you a good, hot spark .
.. bUt the Wrong way gives you a
weak one .
.. and poor performance.
The confusion comes becaUse tHere're two di¹erent capacitors used in a
point¸type ignition system.
ºne capacitor»the filter capaci¼
tor»is between the pri½ar¾ cable
connector and the coil. Its lead goes
to the"+¿ terminal on the coil.
The othercapacitor»condensorÀ
is mounted next to tHe points. THe
lead from that capacitor goes to the
points.
Another wire goes from tHere to
the"Á¿ terminal on the coil.
If you reverse the hookups to the
coil, you get about ±0 percent less
voltage to the plugs.
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