Morning all,
While I fitted my new clutch the FD was sitting around the shop with the speedo sensor still fitted. It has previously worked fine and wasn’t abused while it sat on my bench.

After refit, no work.

The rest of the cluster still works fine so probably not an earth problem at that end.

The self cancel indicators don’t work, another indication that the sensor signal isn’t getting through.

I’ve deoxed the connector behind the side panel.

I’ve tried the soldering iron trick, not a flicker.

I’ve multi metered the connector behind the side panel and get a reading of around .3 V AC at tickover in first and this value seems to increase with engine speed.

The last post I’ve read on this says to expect a reading of around .1 V AC. It seems like if I’m getting a reading at all, then the sensor is probably working, regardless that it doesn’t produce any of the meter readings I’ve seen referenced here.

My questions are:

if I’m getting any reading of any value at the connector that increases with engine speed should I be looking further upline for a (probably connector) problem or could the wrong numbers still indicate a faulty sensor?

I know that there is a gap tolerance dimension between the sensor tip and the FD pickup, my sensor tip is almost flush with the sensor case, issue?

Is there a resistance (or other) test that I can do with just the sensor through to the first connector or would that only indicate connectivity rather than proper functionality?

Not stressing on this one as my gps shows speed, but I would like to get the odo and self cancel back on line.

Cheers, Stu

There's two variants of the sensor; one's easy to break and the other isn't. Piccy please?

Can't do piccy atm, on way to panto (oh yes I am) but it's the one that fixes with a single Allen bolt at the rear of sensor and a T connector behind the side panel.

They're all like that {sigh}. Are you sure you can navigate to North Wales?

Seriously though, most are a sealed unit with a single screw to hold it to the FD. There's one type which has two screws in it - this type can be taken apart. It's not sealed very well, so water can get in and corrode the terminals. I had one like this, fixed it by soldering in new wires, sealed it with epoxy, ran it for a few days and then introduced it to the bin. I just didn't trust it not to fail again.

Piccy tomoz. I'll also put a jumper across that first connector because that's really the only component I've touched. 
And it's unfair to ask about Wales, I won't know the answer til I get there. 

you can measure the sensor at the connector \
if some low resistance , could be ok ... if none ...its toast , not to discount that the connector itself may be faulty

do any measuring without any electrics turned on

there is usually some small voltage going to the sensor from the speedo (dc offset from the amplifier input )

hope that helps

Jumped connector, still no response. Re-tested for continuity off the bike, no show.
Removed sensor from body, the push fit wires were a bit cruddy and felt loose in the housings.
Ordered a one used from Motorworks. Thanks for the input.

Yup, that's the easy-break version. Take the small screw out, push the cable through the hole (don't try and pull the housing cover) and if you're lucky, you'll expose the two terminals. What I did was get a look at the terminals and found one was a broken green mess, so I cut the wires and pulled the cover off. There was just about enough brass left after cleaning to solder two new wires on.

Dai wrote:Yup, that's the easy-break version.

Spot on Dai. My used replacement arrived and it is the sealed unit variety. Obvious straightaway that its a more robust bit of kit, and it works.
Glad I didn’t waste my money on that Ordnance Survey map of Wales, which also arrived today.