docc

This makes me wonder about the primary battery negative ground to the back rear of the gearbox. Has that been seen to?

Okay, voltage reference wire is intact, then. What are the two wires truncated (nutted) in the image? Red-green would be the charging back to the battery through Fuse#3 you bypassed. But the black wire? Even with the case grounded to the timing chest, there would be nothing wrong leaving that regulator ground connected to the battery negative terminal.

Test Ohm resistance from the red/black wire on the harness side to the Relay#2 output . . .

Well, there is continuity through that circuit (good). Not sure if 15 Ohms is high. What is the Ohm reading from Relay#2 to the black wire at the regulator connector?

If you set your Ohm meter to a higher setting, say 2kΩ (2000 Ohms), the reading between the terminal you arrowed and the regulator connector at with the lighter wire (not black) should read > 0 < (zero) indicating no resistance (continuous/connected circuit). The "center terminal" position, being the middle of the smaller three doesn't have a connection in the socket (empty). The Ohm reading from anywhere to that empty socket should read > 1 < or infinite resistance (no connection). There should certainly be > 0 < (zero) Ohms from that indicated relay connection to the black wire at the regulator connector ("voltage reference").

Location of said oil pressure switch. Yours will not have the rubber boot . . .

I wonder if you lift gently on the bezel while loosening each screw a little at a time that it will slowly come up and off. It would be nice to verify the bulbs are good and get some Caig DeOxit on the contacts.

Eastern Kentucky has bigger hills and deeper valleys than the Talladega, Alabama area, but all good riding and friendly people. We would call them "mountains", but those from the western US or the Alps say: Er, no.

True, but VRLA, so the voltages are higher overall. Plus, the Odyssey apparently has some specific charging parameters. Especially either regard to "trickle chargers.

Hey! I resemble that remark!

Ah - I was going by the 12.3v you reported. 12.84v is 100% for an AGM. Chart below is for a non-AGM lead acid battery.

Oil light should come with the ignition, prior to starting and extinguish almost instantly on start-up. At this point, your battery is really flat and should be charged. If it's a Hawker Odyssey at 12.3v, perform a proper "conditioning" . . .

We're just all working together, my friend. You are doing a great job reporting back what you find. If we cannot find a bad connection somewhere, the new regulator will, indeed, be suspect as faulty.

The black wire of that connector is the "voltage reference" from Relay #2 ("Headlight Relay") and should have no output from the regulator. The harness side of the black wire should be near battery voltage with the key on. The white (or lighter) wire should ground through the warning bulb. An ohm meter through the harness side of the lighter colored wire should show continuous to ground. Also, a test light from the positive terminal should light when connected to the harness side of the white/lighter colored wire (which should also illuminate the warning light).

That housekeeping done (y'all carry on with that Texas bid'ness! ) . . . I have to tell this South'n Spine Raid story, lest it fade away . . . Late night in the Tellico Garage, the question of "Why a Guzzi?" came up. One revered SpineRaider spoke up ( I paraphrase, but not entirely!) . . . "I was always a Ducati guy and hated Guzzis ." >hated<. "One day I was at my dealer and walked by a SPOrT 1100 from behind. I squatted down and looked at it from behind. " "It was like your girlfriend bending over in some hot shorts. " Some quick-witted SpineRaider noted he said: YOUR girlfriend, not HIS girlfriend . . . Either way: he's been a Guzzi guy ever since.

After somewhere around six drift posts, they find their way to a better home . . .

I use Mobil-1, too. Not in my motorcycles. Where do they declare their actual base oil? If the base oil is not Group 4 or Group 5, the motor oil is not "full synthetic" in spite of the marketing statement on the face of the label. I've abandoned popular oils because the manufacturer will not provide the specification if the base oil.

+1 on "Wiggle Testing." The corollary of my supposing that finding the charging fault may fix the light is: affecting the light may reveal the charging fault.

Not to steal @LaGrasta's response, but Fuse #4 has its own, separate ring terminal to the battery positive. The regulator's charge to the battery can be changed without affecting the other connections to the battery.

It occurs to me that addressing the charging problem would be primary. Once it is charging, the light behavior may take care of itself.

Don't let the metal blanking plate/ disc jump out of your angle drives. Perhaps made more likely by adding viscous lubricant to the housing . . .

I cannot find an image of the earlier bolt, but pretty sure the only change was the finish from the earlier, black phosphate-looking bolts to the later, silver "Geomet corrosion resistant finish " . . . Certainly, this is group of fasteners that would be unfortunate not to be torqued correctly a.k.a. "tight " . . .

The only torque spec in the Workshop Manual for 10mm is 1.5 thread pitch in the English and Dutch translations, but 1.25 in the German translation. Guess we'll go with the two-out-of-three consensus. The part number does change between the early Sports (GU98623530) and the LeMans (GU98683530 ) Here is a listing for the later number: https://www.hargloperformance.com/genuine-moto-guzzi-hex-socket-cap-screw-10x30mm-fine-thread-geomet-gu98683530-10313-p.asp I don't see a size change across the V11 range, @phalford. For sure your caliper mount bolts measure 8mm?

Thanks for checking! What's that thread pitch?

True. Torque spec based on both fastener diameter and thread pitch, yes? I don't think I have a loose caliper bolt lying around to measure. Anyone?