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Discussion Starter · #1 ·
Hello all. Relatively new to the forums, and to riding a CX500. I'd rank myself as a novice when it comes to mechanical work - I'm OK with oil/filter & spark plug changes and basic adjustments, but am not well versed in much else. That being said, when I was changing the spark plugs the other day I also re-adjusted the brakes when I noticed that the rear brake light was not going on (before the adjustment as well) after adjusting the brake peddle I started to adjust the brake light sensor and I have turned it clockwise to almost the maximum I can go without the lock nut coming off the sensor adjuster. I've also swapped bulbs with the front brake to test the bulbs themselves, and the bulbs work fine. Are there any other tricks or suggestions a novice could look to try to fix the problem before I cart it off to the mechanic? Thanx in advance for your time.
 

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can you confirm the rear brake light comes on when you pull the front brake lever
 

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Discussion Starter · #3 ·
yes, the second filament (the brake) in one bulb goes on when the front brake is depressed, but neither brake filament of either bulb goes on when the rear brake is depressed (so it's not 'stuck' on either.)
 

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Do you have a voltmeter/tester?



If you are going to own a 30 year old bike, it is worth the small cost.



Cheap at Canadian Tire stores.
 

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Discussion Starter · #6 ·
correction - on a hunch changed the bulbs - now both filaments light when the front brake is depressed and not lights when the rear brake is depressed.
 

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when you adjust the rear brake at the wheel its quite normal to have to adjust the switch as well.follow the rear brake linkage and you will see the switch,have a go at adjusting that as well
 

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Ok there are alot of guys here that know tons more about these bikes than I do.



But, really just look at what you know already, the rear bulb works when front brake applied.



So if the brake light is not working when rear brake is applied then the fault lays within the rear brake power line or actuator.



Take your tester and find a good ground, verify it is working by touching your positive battery cnx.



Find the wire at at the actuator, and apply the rear brake and see if you get a reading.



All you really have is a source of power to the actuator, then back to the brake light, if I am not mistaken.



So if you have power at the actuator on the battery side, check the brake light side, if that is good, then maybe the wire from actuator to light is crimped/sheared, so check the wiring routing.



I may be wrong in my diagnosis technique, but I know that someone here will be able to guide you to the solution.



Good Luck.
 

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I had a rear-brake pedal switch go bad on my 78. IIRC the Honda dealer can still order them. Not hard to change.
 

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Discussion Starter · #10 ·
Thank you for everyone's input so far. Work is a bit hectic so I will not get a chance to take a look at it closely again until Wednesday evening and I will try everyone's suggestions then. I was at the Honda dealer today (Daddy got his new pair of waterproof boots) and was talking to them about the problem. They said sometimes the brake sensor gets over adjusted and past a certain point the brake light will not come on - so I'll add that to my check list as well and post what I find. Any yes BrianB, you are right, in the event that the sensor is bad, the part is still available and it's not too expensive. Thank you all again.
 

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If the switch has not been adjusted for while, it can get 'sticky'



I'd suggest you remove the spring, pull the switch out (no need to remove the elctrical connections yet - just check they are plugged in when your done).



Spray some contact cleaner into the switch. -(or wd40 or other thin oil in a pinch)

Clean the metal pin with some 'wet n dry' paper? or a wire brush? (Not sure what you call this in the US!)

and use your fingers to pull and push in the metal pin a few times.



If the ignition is on and wire are still in place, then after a few minutes of 'worrying the pin' you'll start to see the brake light working!



If not - then you have some loose connections (cheap!) or a bad switch (quite cheap).





BTW - I had lots of problems with my switch in the past. This fixed it. I also made the spring a little shorter so the switched would get a better pull from the brake pedal.

Also, if you do need to buy a new switch - remember the custom (and possibly GL?) need a different switch with longer wires.
 

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Discussion Starter · #13 ·
Thank you everyone for your help and sorry for the slow reply. After playing with the sensor, I noticed it was stuck. After cleaning it up, it still did not work, and did check all the connections and all seemed to be good and clean, so I did wind up replacing the sensor. A cheep one with the shorter cables was used and with a bit of 'meatball surgery' using the wires from the old sensor to extend them and viola - a working sensor. The spring is a bit overused and not 'snapping' the sensor back in place(thus the brake light stays on a bit too long,) so will try to clean the spring up before replacing it, or shortening it as IanSmith has suggested, but at least my pedal brake lights are now working!
 

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Ok...I have the same problem...rear brake does not activate light. Where is the sensor at? i went and looked and can't find it. I'm kinda mechanically retarded, lol
 
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