> Now, having replaced the harnesses and relay, it works only if I run an
> out-of-harness ground from the switch to a convenient spot.
According to Dan's schematic, the operating switch is normally grounded
through the isolator switches on the gearbox top cover. Sounds like perhaps
the isolator switch for the gear you've selected is intermittent. Or, of
course, the connections to the switches, the ground lead from the switches,
it's connection to ground, etc.
> Also, without
> the extra ground, the solonoid engages when I turn on the ignition key!
> Whether or not the switch is on.
That sounds like a short somewhere else. I'd start by using a test lamp or
voltmeter to check the voltage (to ground) on each of the 4 relay terminals.
W1 & W2 should be at +12. If not, the short is somewhere between W2 and the
operating switch (or in the switch itself).
If W1 and W2 are both +12, you should find +12 on C1 and zero on C2. If
not, the relay itself may be bad.
Note that the W1 may be interchanged with W2, and C1 with C2. Might be
worthwhile checking to see that your car matches the wiring diagram.
Just as a side comment, the solenoid has contacts inside. If they are dirty
or no longer working, the result can be erratic operation. Also, the 'drop'
of the solenoid plunger can't be too large or erratic operation may result
(not to mention a burnt up solenoid).
Also, attempting to backup with the OD engaged can cause some expensive
damage. If you start to back up and it feels like you're against a curb or
something, don't force it !
Randall
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