Electrical gremlin in brake system

[Rapier]

I have finally had time to do additional troubleshooting and I think this is an electrical gremlin and not a brake switch issue as originally posted:
https://wildguzzi.com/forum/index.php?PHPSESSID=aff7e089fea2b3acebcfba335d22f2d4&topic=119027.0

Summary:
-When the bike is turned on the brake light flashes (as expected with LED) and then stays on at full power.
-Removed LED bulb and put in original incandescent (no change).
-Tested the taillight assembly and there is 12V at the tail. Regardless if the brake is activated or not.
-Cut the brake switch electrical cables to remove switch from the equation. No change stays on at full power.

What has gone on before:
-Bike has been running for a year with no issues.
-No changes have been made in over a year.
-No change to brake light when activated at lever or pedal.
-Fuses are all unbroken and tested with meter.
-The bike stops when applying either the front or rear brake (as expected).
-May of 2022 SATO rear sets were put on, this includes a new brake switch.

Anyone have any thoughts?

[guzzisteve]

Get a new rear brake switch, they don't last forever.

[Rapier]

I did remove the break switch from the equation and the light stayed at full power.
Shouldn't the brake light turned off when the cables are cut?

[bmc5733946]

Might the bulb be misinstalled? Pay close attention to the offset pins on the bulb base and their positions in the bulb socket.

Brian

[drdwb]

In your post you mentioned taking out the Led bulb and installing an incandescent with no change. I and a couple electricians I have spoke to noticed when we have replaced incandescent bulbs with leds in house lights some wall switches quit functioning properly after a while. I first noticed it in a bed room ceiling fan with a dimmer switch, the switch would emit a high frequency buzz, heard only when laying in bed, after a few months of trying to locate the buzz,I noticed occasionally the lights would flicker when dimmed and at times the buzz and flicker were happening at the same time, one evening the switch felt hot to my touch when turning the light all the way off. When I went to the local big box home center looking for a replacement I noticed some switches were labeled as acceptable to use with led light bulbs, more expensive of course.

Long story I know, but if you changed to leds something in the path from source through switch to light, may have been to weak or unable to handle the change. Reading your post I realize you took the switch out, and didn’t find a problem, if you had a spare switch, or perhaps swap any relay in that circuit you might stumble on the answer. Sounds like your wiring is intact, so I’d start looking at components in the circuit.

By the way any electricians reading this might chime in about this being all BS or if it is a real problem in home wiring.


Good luck, I hope to read very soon that you found and fixed this.

[John A]

Have you checked the socket? It’s common for them to melt and deform, especially with a brighter bulb but it happens with a standard bulb as well. You can also disconnect the harness under the seat to isolate the rear section for troubleshooting.

[Tom H]

I'm sure you know this. But...

With the key on, you should have the headlight and tail light. If you take a test meter and poke around in the tail light socket, one terminal; will have 12V all the time when the key is on. The other terminal will only have 12V when you hit a brake lever.

Also, what type bulb, 1157 style?

Also as mentioned, the bulb socket itself could be having issues allowing power to go to both terminals at the same time.

Tom

[StuCorpe]

May be a dumb question but there are 2 brake switches (handlebar and foot), did you disable both of them?

[Tom H]

With the work you did previously. You didn't happen to hook the brake light circuit to the tail light bulb filament, and the tail light to the brake light filament?

This would give the look of the brake light on all the time. But if you hit a brake lever, you'll see the smaller filament light up. With the brake lever applied and the tail light on, both filaments should be lit.

Quite easy to hook up the wires backwards.

Tom