Locking differential questions (80Q)

[Andrew Duane USG]

Hairy green toads from Mars made Kneale Brownson say:

> The lockable rear diffs are supposed to unlock automatically above
> something like 15 mph and relock when you return to speeds below that for
> as long as the lock switch is engaged.  They're intended for things like
> getting out of a parkinglot full of snow or a shallow ditch, etc.
>
> At 06:19 AM 12/06/2001 -0800, Jim wrote:
>
> >I pushed the "Lock Diff" button on my "new to me" 1990 80Q the other day
> >and nothing happened. OK, so it's broken I thought, no biggie. Shortly
> >after I started noticing odd behavior in tight turns (it would kind of
> >"wind up"). It took me a while (OK, so I'm a little slow!) to realize that
> >it really was locked. Pushing the button again seemed to fix it. So a
> >couple questions:
> >
> >1) After I pushed the button I drove the car on the highway. Isn't it
> >supposed to unlock over 30MPH? Does it automatically lock again when you
> >go below 30MPH?
> >
> >2) Is the switch a momentary connected to a controller or is it really an
> >on/off switch?
> >
> >3) Is the diff. vaccum or electrically activated?
> >
> >4) I assume there is a light that's supposed to go on? How hard is it to
> >fix the lights in that little panel next to the switch?

Not on these cars. The diff lock is a momentary switch. If the car
is going less than 15 MPH, it toggles the diff lock on (or off).
If the car is going more than 15 MPH, the diff lock stays off no
matter what. It will not go back on automatically when you drop
below 15 MPH, the button needs to be pushed again.

When the diff lock is on, there is a light in the switch itself that
lights up, and the "ABS OFF" light in the instrument cluster also
lights up, since ABS is turned off with the rear diff locked.

Now, on two out of three cars I had with this switch, the switches
sometimes collect crap and get sticky, which could cause some wierd
behaviour. Does the switch oeprate freely? go in easily and return
to the rest position?

--

Andrew L. Duane (JOT-7)			duane at zk3.dec.com
Compaq Computer Corporation		(603)-884-1294
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