Re: TURN SIGNALS PART II

Posted by sgtslag on Oct 25, 2011; 3:26pm
URL: http://vintage-and-classic-hondas.81.s1.nabble.com/TURN-SIGNALS-PART-II-tp3446376p3451703.html

Is there a light failure circuit shown on the schematic?  My Voyager has a 'black box' that controls the headlight filaments:  if one filament burns open, the other takes over, regardless of the switch position, with the Hi beam filament running at a lower amperage, to mimic the function of the failed Lo beam; there is a dash light to show a headlamp failure -- when the Hi beam burns open, it just runs on Lo beam, no matter what.  Anyway, if there is such a box, or failure circuit shown on the schematic, then things get a bit more complicated.  Any such failure circuit is doubtful on a '77, but it's possible.  If there is such a 'black box' device, it will be shown, and labeled, on the schematic.

Another potential gotcha', is the dreaded "floating ground", where the circuit is not properly grounded.  This creates very strange symptoms.  It is easy to test, though:  put your digital Ohmmeter (not recommended for analog/needle deflecting meters...) leads between the ground lead on the left turn signal, and the negative battery terminal, and see what the resistance reading is.  It should be <2 Ohms.  Do the same with the headlight:  measure the resistance between the ground plug on the bulb, and the negative terminal on the battery, it should be <2 Ohms.  By the way, testing for good ground connections, is much easier than tracing wires through the harness, so I recommend these tests first.

If you do not have any electrical terminal/contact grease, get some from your local auto parts store.  Apply this to all contacts, and connectors.  It will prevent them from corroding, ensuring good electrical connections, preventing weird problems down the road.  With older bikes, corrosion on contacts, and connectors, can be a major source of headaches.  The best practice is to clean the contacts, first, with a brass brush, then apply the grease.  If they're already corroded (white, or green, fuzzy stuff on the metal contacts), the grease *might* improve the connections, but brushing them with a brass brush to remove any corrosion on the metal surfaces, is the best.  Cheers!