turn-signal, temp guage, and oil pres. warning probs

[nicholls@mikey.convex.com (Sam Nicholls)]

My '86 4000S has an intermittent turn-signal failure.  When the problem
happens, if I try to activate either the left or right turn-signal,
the dashboard turn-signal indicator stays lit (doesn't blink) and
none of the external turn-signals light up.  Also, activating the
hazard switch doesn't do anything.

Sometimes the problem happens as soon as I start the car.  Sometimes
it happens after I've been driving awhile.  Sometimes the problem
goes away after a few minutes.  Sometimes the problem doesn't go
away until the next time I drive the car.

Also, the coolant temperature guage reads 0 all the time.  Except,
once, after I drove home, I noticed that it was working.  That was
about 2 days ago and it hasn't worked since.  I don't know if this
could be related to by turn-signal problem.

Also, the oil pressure warning light (and buzzard) occasionally
turn on for a few seconds.  Even though the oil pressure guage
looks normal (3 - 4 Bars while driving).  The oil and filter
were recently changed.  I don't know if this is related to the
above problems.

I hope the turn-signal problem is just a faulty relay and that
the temp guage and oil pressure warning problems are just faulty
sender units.  But, could this be a more subtle electrical prob?

Any advice will be greatly appreciated.

Sam Nicholls <nicholls@rsn.hp.com>
'86 4000S (with only 40K miles thanks to the busted odometer 8-)