Did my test of the resistance of the wiring & GPs do any good at all?
Yes, it appears that your test has cleared the GP's themselves of
being completely dead. But there is still room for doubt given the
borderline ability of most meters to give accurate readings in this
range.
Should I ty to get Mercedes to fork over a new relay? If I tell them I
You could try, but were I they I'd want a little more proof. You
need a hefty ammeter, or that series glow plug. I like the clamp-on
DC ammeter myself, because it's also good for measuring things like
starter current, etc. They're not particularly cheap, but they can
certainly be had for less than my Fluke cost me.
One of the 'toaster racks' from a series-GP MB would also work, with
a voltmeter. All you're really doing is looking for imbalances among
the GP's, but you need something capable of taking 20-30A of current
without melting or dropping too much or too little voltage in series
with the plug. (Untwisted wire coat hanger with the ends filed clean?
It's a substantial length of iron [poor] wire, of smallish diameter.
Just grasping at straws here.)
I still have the old relay - and it's got a card filled with soldered
joints
holding lots of little things in line. If I test those for continuity
will
that help point to the part that's possibly bad - or has a bad solder
joint?
Unlikely to be of any success. Resoldering them, if you can actually
solder well, may work wonders. It restored the one in my 190D to life.
(Though it seems to be timing the light too long right now, I need to
look into that sometime.)
I may re-install the old relay to see how things act.
Couldn't hurt, and could give you another data point.
OK - back to the new relay and new GPs - it seems like either #1 is
bad or
the relay is bad - sound reasonable?
Really it could be any of the GP's, though it is most sensitive to
poor behavior on #1. Or the wiring to them. Unfortunately you really
haven't completely ruled out anything yet. The next test is a current
test of each plug, you need to figure out a way to do that.
-- Jim
