Hand brake light switch repair on the fly

[Hogzilla]

I discovered my brake light wasn't working via the hand brake a few weeks ago so I went to get a replacement switch from one of my 3 donor bikes.  I have an '85 700sc, btw.  Turns out two of the three switches were bad, leading me to believe this is a fairly common problem and likely across many models.

I thought I would burn up a few more characters showing this very simple fix which can be accomplished in about 15 minutes.
I know this is all really basic stuff for most folks here but possibly someone who isn't a tinkerer and hasn't seen behind the curtain of DC wizardry can be helped by this.  FYI, you will not get shocked doing this repair and therefore no need to disconnect the battery.  It is also not important that the wires get hooked up to the same connections in case you forget.

Below is the first switch I broke into which exploded (spring) when I took it down further than I really needed.  Here you can see most of the entire guts of the switch.


To make a quick repair, First remove the switch from the bike which is held in place by a screw.  You can use a small cross-top screwdriver such as a philips head (which is likely to be found in most tool boxes) but to be proper, a JIS style driver is the appropriate tool for this job as has been pointed out in the comments.   Of course, if all else fails or you find yourself without such tools then vise-grips, pliers, teeth, P-38, house key, or whatever implements you can source or may have in play to remove said screw can be used assuming it is a screw at all. 
The switch is a 1" square plastic bit with two wire connectors and a single small screw holding it in place.  This switch is located on the bottom of the brake handle assy.   Sorry none of the pic I took really added any clarity.



Using a sharp bladed knife or very slim flat screw driver to pry open the case.  Pry around the edge perimeter and lifting and twisting as you go.  It will take some effort to crack open the tabs but gentle pressure should preserve the integrity of the casing which is more durable than you might expect.


Here is the inside with the top cover removed. Note that the cover will snap back on securely when finished.   You do not need to take the interior metal cover off the remaining insides of this switch and in fact you want to be sure that interior plate stays in place.
At the top is the activator switch.  The brake handle, when at rest, keeps this button pressed inward. It is released when you squeeze the brake handle allowing the contacts (lower right part of switch) to... well... make contact.


This is a more clear view of the switch contacts which are the parts you will be concerned about.  These get filthy or worn preventing a good electric connection and thus, no brake light.  Also note here that the lower contact (to the right of the pic) is at the end of a single flat bar which leads to one of the two wires from the brake assy.  I removed this to make cleaning a bit easier.  It simply slides between plastic tabs in the switch assy body.


Remove the lower contact tab then used the knife (or flat screwdriver) to scrape off the surface corrosion and filth build-up as best as you can. You can see the pitting better in the second pic. I did the same on the upper contact but be careful not to pop that upper contact out.  I pressed down on the metal plate while scraping in order to keep it all from lifting up. 


Once scrapped, and hopefully a bit more shiny, reinstall the lower contact tab.  You should probably bend the contact end upward and bend the upper contact downward to assure they will make a strong connection but still allows for a gap when the switch is not engaged. Press the switch button to review the action but keep your thumb on the internal metal plate while doing so.  those internal parts will flop out if you're not careful.

When finished, snap the top back on, and reinstall on the brake assy noting there is a locator tab on this switch casing to assure you get it in upside-right and correctly aligned.
There ya go! Not much to it!... 

You may want to order a new switch because springs wear out, and it's best to consider this a temporary solution.  But hopefully this will get you back on the road while you wait for that delivery.

Thanks, and maybe I'll do something a bit more complex later on.

[mollusc]

Note that although a Philips will work on a small screw like the one holding this switch, there are NO Philips-head parts anywhere on a stock Honda, and using a Philips bit on one that is tight will probably destroy it.  Everything is JIS, so if you plan on doing anything remotely involved, get yourself some correct bits before you start.

[Pete in PA]

The last one of these I worked on had access to the points through a small hole.
I just took a small piece of sandpaper and sanded them and back to working.

[Bob H]

... Everything is JIS, ...get yourself some correct bits before you start.

Right. I have had good luck with Vessel Tools JIS and that link explains the difference.
The main thing is to always "test fit" the screwdriver (wobble it around, see of it is sloppy or "locks in place" like it should).
There are so many variables. Even the JIS standard has changed, to some sort of international standard, so many of the newer "JIS" screwdrivers being sold as JIS don't fit well on something from the 1980's. I have about 5 JIS screwdrivers, with some JIS impact bits etc. and they are not consistent with each other and not consistent with an american "Phillips" craftsman screwdriver.
If you learn 1) that there is a potential issue and 2) to at least see if the screwdriver wobbles before using it, then you are a step ahead of the game.
https://www.motorcyclistonline.com/difference-between-phillips-and-jis-head-screws/

[Pete in PA]

I have various JIS screwdrivers and bits.
+the most important item...An impact driver.

[Hogzilla]

Right then...Thread updated...I think the general idea persists but who doesn't like a reason to justify buying more tools!?

[Hogzilla]

The last one of these I worked on had access to the points through a small hole.
I just took a small piece of sandpaper and sanded them and back to working.

Hmm.  I'll have to look and see if there is such an access port--didn't look or notice to be honest. I would be curious if this was a design feature or a handily placed condensation relief port. 
I will add though, that partial responsibility for the problem on at least 2 switches was misalignment to such an extent that, even after cleaning, I had to bend them slightly to assure a more consistent contact.