Speedo Sensor - Aditional Info

In trying to help a Breva owner with a dud speedo I learnt a little more about our speed sensors.

I assumed they were a simple reluctance sensor but no, they are a magnet biased Hall Effect switch, when the target passes the sensor it distorts the magnetic field causing the Hall Effect to change state.
From what I found out looking at generic switches of this type they have a very short range, only about 2mm.

Note: This is a printout from a V7 but I suspect they use the same sensor.
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Don't forget to seal the cable going into the sensor or for sure it will fail in the wet. The epoxy body is hard and the cable soft. The cable is not bonded but can move away from the body creating a perfect crack to wick water into the sensor where it will corrode or short out the connections.

Use a silicone sealant that won't go hard but flex with the cable.

I found that I can measure the output pulses if I plug the probes of my meter into the back of the 3 pin socket (loom side) Negative to pin 3, Positive to pin 2
I get a reading that drops from 10.4 VDC to 0.3 as the targets pass the sensor.
If the Voltage fails to reach 10 Volts it's probably moisture leaked through the gap between sensor and cable shorting to hold the Voltage down, try warming it up for a few hours, it may drive the moisture back out.

It's also possible to prove out the speedo itself from the 3 pin connector, I need to do some further testing on that to figure out the best way but I found simply touching a wire from pin 2 to 3 on the loom side will cause the speedo to read up scale (up to 300) for a second or two.

Read this Roy it might help  [You must be registered and logged in to see this link.]

I followed the recommendations here and did the same on my Breva 1100 and it worked straight off the bat

If you do it though, before you lock the air gap down, ride the bike to your "Maximum Normal Velocity" and check that the speedo works properly

Above a ton (on a closed road officer) mine has a little hissy fit 

I have been trying to help a guy with a Breva 850 sort out his speedo, we discovered the Breva uses a Honeywell IGP7001 switch potted into some plastic material.
I checked on my GRiSO, the speedo puts out a current of 3.3 milliamps to pull pin 2 of the connector high (about 10 Volts) the switch is capable of sinking 40 Milliamps, when it turns on it pulls pin 2 down from 10V to about 0.33 Volts.
The GRiSO must use a different switch (flatter package) but chances are it's a Honeywell also.

So it's very easy to check your speed sensor just plug the positive lead of your multimeter into the back of pin 2 of the 3 pin connector, the negative lead goes to pin 3 or chassis.

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Note:
Although this sensor is not used on the GRiSO the testing was carried out on my 2007 1100

my screen goes blank after a few miles, comes back to life after a restart, goes blank. its a dry ride and the wire into the sender has been siliconed..........

Is that just the LCD or the complete dash?

just the lcd. I think the idiot lights still work, but the 3 way toggle between screens, speedo, digital icons all vanish to blank grey screen. but recover when restarted. I have gone through and removed fuses and or disconnected batt to reboot. but nothing lasts. I dont really just want to start swapping parts and Im not too good with an electrical testor, but I do know someone who is. any info appreciated. thanks

other dumb question of the day.........It will run this way and not leave me stranded. I can run without a speedo and readout. i.e. I dont have to store this till I locate the sensor......I already checked my mgclassics and its not listed. didnt pop up on af1-dallas, either

mmmm sounds like the ribbon cable that feeds the LCD is on its way out.
it is integral with the LCD, and a replacement unit has yet to be found I'm afraid.
it should run quite happily without the display however. The mileage info etc is stored in ECU.

mine was 'repaired' with acupressure.... a bit of packing was used to keep it working...
-this was done by an automotive instrument technician who specialises in modern LCD units.
he has global contacts for dash parts and could not find a replacement.

I think that was about 18 months ago... it's still going -touch wood.
there are several threads on here about various attempts to repair.
a new dash is often the only fix.

sorry about that.
I was quite lucky I think.

bahamazoo wrote:

mmmm sounds like the ribbon cable that feeds the LCD is on its way out.
it is integral with the LCD, and a replacement unit has yet to be found I'm afraid.
it should run quite happily without the display however. The mileage info etc is stored in ECU.
.....

I agree

Mine did exactly the same and ran quite happily for a year or 18 months until i sorted it out.

I was lucky to pick up a secondhand dash for about £40 and once I'd transplanted the LCD from it into my dash normal service was resumed

wow, £40!!!
win.

was there anything 'special' about swapping the LCDs??

Its a bit scary breaking it open, but definitely "do able"

There are other articles, but this one was a great help!
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A couple of things if you decide to go for it.

Get hold of a small sucker - the type used to sick a decoration to a window for example. You wont be able to get your fingers around the LCD to pull it free once you move the clips out of the way unless you use the sucker to pull it
Levering isn't a good plan given that its all glass!

There is a brown clip that holds the ribbon cable into the plug on the circuit board. You need to move this out both edges to release the cable

You may or may not be able to get the circuit board out of the dash if you feel the need. It appears some are soldered in (like mine) and some are not

TTFN and good luck!