SWITCH, PARKING Forum

Product info

I've recently found the reason why my brake lights do not work. The automatic models have a requirement for an emergency brake because they cannot be left in a gear. Honda thought it prudent to put a light on the right instrument cluster to indicate that the park brake is on. This is helpful when diagnosing why your bike doesn't move when put into drive and the accelerator applied.
This switch is located above the rear brake arm and enters the aluminum support housing.It connects power to the lamp. Only the Automatic specific wire diagram has this info which I found in the Haynes manual only. This is about the only worthwhile info I actually found in this marginal manual. Honda's shop manual doesn't even have a wire diagram

I digress here. It turns out that the switch has an additional function (hence the 4 wires going to it). When the park brake is on, the circuit to tail brake light is opened.I guess this allows the park lights to illuminate with parking brake on, without the added current draw of the brake lamp.If you were disabled along a busy motorway,on a hill, at night, perhaps this might help.

Honda seems to have gone to a lot of trouble making this bike lighter after that enormous automatic transmission was added.Things like the aluminum wheels comes to mind. They also made this brake switch housing out of aluminum. This might have worked, but the addition of non aluminum electrical parts inside made for exceptional galvanic corrosion inside. When I removed the switch boot,it literally fell apart into white powdery residue with some corroded metallic connectors still attached to the 4 wires.

Naturally, this part is no longer available. The short production run of the CB750 Hondamatic was no doubt the real cause. The corrosion problem was never addressed by Honda and now the spares are all gone

What to do? What to do? If anybody has some thoughts on this I would like some advice. The used ones I've seen online (EBAY) come with the caveat "what you see is what you get"and no guarantee to work. None have the boot removed to see the insidious corrosion that probably lurks underneath. All do have a price tag of $100 plus US dollars plus shipping. Taking a risk to purchase and look under the boot doesn't seem worthwhile.

I've thought of making my own simple grounding switch from the remnants of the old one. It could operate two 12v auto relays to connect power to the indicator lamp and another to disconnect the two wire circuit leading to the park brake. But I am not a machine shop or electrical engineer. This task should have been handled by Honda.
Any solutions will be most appreciated!