200 Q automatic unlock diff at 15 mph blue / white wire

Suffolk GameServer LAN suffolk.associates at verizon.net
Mon Dec 9 01:27:54 EST 2002

Repackaged for searching archives.
-Scott in BOSTON

Well, let's understand how that works first.  The rear locker is identical
design and execution as your 4kq.  As of 1988> the rear locker used an
electronic box to engage the rear diff, giving you a push button instead of
vacuum knob.  When they did this, they also added a ground wire to the
controller that is triggered by the ecu speed sensor output.  At 15mph, the
ecu sends a ground signal via the controller blue/white wire, which cancells
the vacuum solenoid that has locked the rear diff, which then allows vacuum
to the open side of the actuator, unlocking the diff.

Without the ground signal interrupt from the blue/white wire, the rear
will stay locked until the driver pushes the switch again.

I know it works this way, and you can convert your 4kq to be electronically
locking, since I did this mod on my 83 urq with lockers.  I haven't hooked
the blue/white tail to anything yet.  For the detailed look of this
conversion, ck out:


Hope this clarifies things a bit

Scott Justusson

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