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Ducati 748 brake light stuck on? Try this…

Just thought I’d share the latest fix for another classic Ducati intermittent fault.

I’d been having a few electrical problems, but tracked it down to a dodgy loom connector. Lots of stuff was going mental, lights were coming on, rev needles were moving by themselves. Replaced the loom. Sorted.

But some extra problems are still hanging about and I’m never sure if the loom may still have a dodgy connector. One problem was that my rear brake light would stay on. But not always. Grrrr! Mostly when I started her up, the light would be permanently on (like I had the brake pressed). I’d go for a ride and when I got back, the brake light was working normally. Maybe 40% repeatable.

Looked online and lots of chat about microswitches needing replacing, losing a dowel rod and foot brake sensors needing replacing. I wiggled everything in a half-arsed attempt to track it down. No joy. I disconnected the rear brake sensor (there’s a really obvious connector just above the clutch cover). The light stayed on. Must mean it’s the front brake somehow.

I turned my attention to the tiny microswitch behind the front brake lever. It had no obvious connector so I assumed it plugged into the headstock loom, which needs the front of the bike disassembling to reach. Not fun. I squirted it with WD40. Pressed it loads. No change.

I decided to unscrew the microswitch to check it. There are two tiny flathead screws and even more fiddly bolts at the back. Make sure you dont lose them! After removing it (brake lights were still on), I pressed the microswitch… brake lights went off. Eureka! Turns out the microswitch had moved maybe 1/10th of a mm back and now didn’t work. The switch’s natural state is on. You have to press it up against a little push-rod that connects to the lever to activate it… and switch the lights off. Confusing I know. When you pull the brake lever, it push-rod falls away (as there’s no brake lever pushing against it) and it deactivated the switch… which goes to it’s normal ‘brake light on’ state again. Makes sense I guess.

Anyhoo, long and rambling way of saying I simply reseated my microswitch a hair’s width closer to the push-rod / lever and it was enough to press the microswitch (turning the brake light off). Don’t move it too far in though, as it will require the brake lever to be pulled in a fair way before the rod has moved back far enough to deactivate the switch (turning the light on).

May not sort your problem out, but it’s definitely something to check.

1 comment

  • mate,
    just read through this. think I’m having the same problem. thanks for putting this up i’ll check it out tonight hope it’s the same thing.