I may be completely wrong, but I thought that all Chevrolets after '89 or so
engaged the front drive axles in the differential via a vacuum actuator in
the S10s or a motorized actuator in the full size trucks. The drive shafts
will always rotate with this setup. I think your problem may be in the
actuator, but one of the readers (Who owns a full-size) on here can tell you
for sure or not though.
'89 S10 Blazer
This is an S-10 Blazer. I do not have a factory shop manual, and you may be
right about the front drive shaft...I guessed it was engaged when the
transfer case electric motor made its "shift", say to 2H.
Can someone point me to this vacuum actuator or someplace in its system
where it can be tested/checked?
Ist step....did the 4WD indicator light on the floor shift assembly
light up? my guess...probably not.
2st.....underneath the battery plate is a vacuum actuated diaphragm
which engages the front differential..
That may not be getting vacuum thru a lever operated vacuum switch on
the transfer case...
Had mine go out a few months ago....aftermarket cost about 30 bucks
but also the diaphragm might be ripped or a vacuum hose split or worked
it's way off the source
The vacumm switch is on the transfer case ( top passenger side) and the
diaphram is on the fenderwell behind your battery. Check for vacum at the
diephram with your shifter in 4 wheel drive. If no vaccum then check the
switch ( three lines) for vacumm and trace out the lines for leaks. If no
leaks and there is vacum at the switch but not at diaphram then switch is
bad. If vacum at diaphram but no hubs locking up then diaphram has a hole
in it. In the previous post he said he could get them for 30 bucks, call
him and have him get you two cuz where i live they are 87 dollars. Hope
this helps you out.
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