1979-1993 & 94 Conv [Subscribe to Daily Digest] |
First of all, thanks to all who have responded. It seems as if I made a mountain out of a mole hill but in climbing the mountain I learned some really useful things that will help me-- and perhaps others-- to avoid problems or to fix the simple ones-- in the future. Bill S: your post was remarkably to the point and clear, thanks very much. Likewise, special thanks to Simon S, the link you provided to explain the basic mechanics of alternator form and function was quite helpful.
So here's the deal-- I reinstalled the voltage regulator and attached the green/white wire to what I now (finally!) recognize as the D+ post. I then reattached the neg battery cable (at least I was smart enough to d/c that before mucking around in the vicinity of the starter/alternator) and all was well (I was slightly afraid that there might be sparks near the alternator but that fear was unjustified/unrealized). Next, I measured all voltages with the system at rest-- that is, with the ignition in 'off' position and repeated measurements with ignition switch in 'run' position (but engine not running. Finally, I started the car, got it to a smooth idle (~900 rpm) and took another look at voltage drops. Measurements below are reported in the form of "at rest", "run", and "at idle" for the several relevant circuits:
At battery terminals: 12.52, 12.52, 14.11
B+ to ground: 12.52, 0, 14.42
D+ to ground: 0, 0, 14.56
A few things are noteworthy: First, recall from an earlier post that, prior to reattaching the green/white wire, readings at the battery were 12V at rest and 12V at idle. I take the new situation (12.5V at rest, 14.11V at idle) as confirmation that I've found the problem. Second, the 14.11V presently obtained at idle may change over time. I had neglected to put the battery on the charger overnight, so it may be a bit undercharged and the alternator is (now) working to get it up to snuff; finally, the difference B+ to ground and D+ to ground at idle is just 0.14V, well within the 0.7V operational spec that Bentley describes.
I'll be damned, looks like we fixed it! Thanks again to all and Happy New Year.
Scott
posted by 68.187.92...
, Thu, 3 Jan 2013 19:38:49, Fri, 4 Jan 2013 03:36:28, Fri, 4 Jan 2013 14:59:56
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