[V6-12v] 1995 90Q Ignition switch/Starter motor...

[Dr. Gary E. RAFE]

Our (usually trusty) 1995 90Q with nearly 140K miles
gave us some trouble the other night during an excursion
to Ann Arbor (45 miles north of here).
Following our uneventful drive up, we stopped for about
30 minutes to do some shopping.
When we restarted the car to head for our destination
in town (about 10 minutes away), what sounded like a
failing shaft bearing (water pump, alternator, etc.)
was heard from the front of the car.
We also noted that certain electrics were not working
either: turn signals, fresh air fan, A/C system controls,
and, as it turned out, the radiator fans.
As we made our way to our destination, the engine temp
rose just above the middle tick on the temp gauge,
with no sign of the radiator fans running.
We found a parking spot on the street quickly enough,
shut the engine down, and opened the hood for a look
(and to let it cool).
After waiting a minute or two with the hood open,
we switched the ignition back "on"
(without trying to start the engine),
and all the previously not-working electrics were
working again: the radiator fans came on high,
then switched to slow after several seconds and continued
to run until the temp dropped, the turn signals,
and the fresh air fan)
With that, we locked the car & continued on to our
evening event.

When we returned in the rain a few hours later to leave,
we found that the starter motor would not engage
(i.e., turn the key to "start" and the starter
motor did nothing), although all the electrics
appeared normal: voltage was at least 12VDC measured
at the cigarette lighter plug, and everything else
seemed to work as it should.

We had the car transported home that night,
and it's now back in our garage.

I've since had a look at my schematic diagrams
for the car, and have a few questions for the list:

 1. Before pulling the splash pan off and poking around
    the starter motor itself, I wanted to check for ignition
    "start" voltage, say, in the relay panel.
    According to my schematic, I should be able to measure
    this at contacts 37 & 38 of relay position [8],
    which is supposed to be empty except for a jumper between
    contacts 36 & 38 (pg 4).
    The relay panel, however, has a "standard" relay
    (431 951 253H) in that position.
    The panel labels that position "Shift Lock".
    The 5-speed, of course, doesn't need this "feature".

    Does anyone know what purpose that relay is supposed to serve ?
    What happened to the jumper ?

 2. I suspect that the starter motor problem & the problem
    with the electrics are related, since they share the
    ignition switch at some point.
    My wife experienced the same problem with the electrics
    twice this summer, both on very warm days (although I drive
    the car mostly, and hadn't seen the problem before yesterday).
    I put a voltmeter on contact 38 of relay position [8]
    today (after removing the relay), and found +12VDC with
    the ignition switch in the "start" position.
    I also noted the "key doesn't return when released"
    problem, which could explain the noise we heard the last
    time we actually started the car (i.e., interference from
    a still-engaged starter motor).

    Assuming that I need to replace the ignition switch,
    does anyone have any "been-there-done-that" comments on
    the replacement procedure ?

 3. I also expect that replacing the starter motor should
    be more-or-less straight-forward, though comments on
    this might be useful, too.

Regards --Gary
--
Dr Gary E RAFE: drgerlists at gmail dot com