I have not been doing any work under the hood recently and the last related thing I can think of was the Deoxit job of the fuse and relay panel.
Any ideas on what is happening?
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It looks like what happens when the motor over rotates. On S4s and later, the headlight lift motor goes in one direction to raise the lights and in the other direction to lower them. The top and bottom positions are sensed based on a set of fingers making contacts on a gear in the gearbox:
If the top position is not correctly sensed, the motor continues and the arm over-rotates, starting down the backside until it strikes the condenser. Alan developed a shield to protect the condenser for those of us who have experienced this problem.
When you manually turn the motor, do you have to first raise the light for it to then continue down? If not, then it may be another issue.
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Martin
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Also--
The light isn't rgidly connected to the crossbar. In fact, you can go lift a headlight manually from the parked position and pull it straight up to deployed position. Let it go and it falls back.
--- Put the headlights in the full-up position, then turn the key off. Gently push back on the obe that worn't fold back a,d you might feel it reengage.
--- Look carefully at the area under the offending headlight to see if there;s something limiting the downward movement. Something is doing it.
--- There's a stop bolt that supports each headlight in the parked position. See it it got moved, or has something sitting on it.
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'89 S4 Auto, black.
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Also, are the 3 bolts that affix the motor/plate in place tightened to a fixed status ? Any play there will throw off the linkage movement I think.
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!! CHECK THE LINK !!
... between the little crank on the motor and the arm on the headlight crossbar. The ends are assembled with white plastic (nylon?) bushings, a washer and a circlip on each end. Once in a while, one of the clips comes off, the linkage bar gets a little crooked, an arm gets bent, the link falls off, and the motor drives the link through the AC condenser and the radiator.
This probably should sit at the top of the "things to check first!" list for problems with headlight motion.
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'89 S4 Auto, black.
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I inspected the headlight raising mechanism and both nylon bushings and cir-clips are in place and look healthy. No levers were bent either.
After manually adjusting the lights by hand I proceeded to try and reproduce the failure but the light retracted perfectly 10-15 times as expected. But on one cycle, the mechanism shuttered so I decided to check the tightness of the 3 bolts Craig pointed out. They weren't finger loose but each of them required a 1/4 to 1/2 turn. I then cycled the light another 15+ times with no issues.
Not sure how or why they decided to loosen themselves but they were loose and I have not been in there before.