Speedo Failure

Steve E

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After the shenanigans of removing the servo abs and being happy with 'normal' brakes the speedo has now stopped working. Happily riding along, stopped at traffic lights. On pulling away no speedo. Anyone have any clues as i am all out of ideas.
 
Steve E said:
After the shenanigans of removing the servo abs and being happy with 'normal' brakes the speedo has now stopped working. Happily riding along, stopped at traffic lights. On pulling away no speedo. Anyone have any clues as i am all out of ideas.
Click to expand...
ABS sensor, or gap to reluctor ring in rear drive unit
 
Steve E said:
Ive removed and thrown away the ABS sensor (on the front wheel). I'll look at the rear sensor tomorrow.
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What should happen, is if the rear sensor fails, it switches to the front sensor as a backup ;)

The rear reluctor ring is inside the rear drive - have you got any play on the rear drive?
 
Santa-2512 said:
What should happen, is if the rear sensor fails, it switches to the front sensor as a backup ;)

The rear reluctor ring is inside the rear drive - have you got any play on the rear drive?
Click to expand...
No Play in rear drive. Removed speed sensor and it had a christmas tree of debris. Carried out final drive oil flush and replenish. Took for ride and still no speedo. Thinking of getting a new speed sensor and see what happens.
 
The wiring on my rear speed sensor failed on my bike. (non ABS 2006)
The speedo was erratic, seem to remember the self cancelling signals were not going out too.
I traced the break and repaired as the price of a new one was a bit high.
Strangely, the break was at a fixed point with no flex at all on the wire.

Sent from my M2007J22G using Tapatalk
 
Steve E said:
No Play in rear drive. Removed speed sensor and it had a christmas tree of debris. Carried out final drive oil flush and replenish. Took for ride and still no speedo. Thinking of getting a new speed sensor and see what happens.
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That isnt good, and may well be the cause of the problem.

You could try finding the plug, connecting a meter and spin the rear wheel, you should see pulses as the coil is triggered..

If i recall a new one is north of £100
 
Santa-2512 said:
That isnt good, and may well be the cause of the problem.

You could try finding the plug, connecting a meter and spin the rear wheel, you should see pulses as the coil is triggered..

If i recall a new one is north of £100
Click to expand...
Found plug. Put a meter across it with engine running out of gear 0 Volts. Put into gear (on centre stand) meter across pins is constant 1.64 Volts. I presume that this means the sensor is kaput? New sensor from motorworks is £160. Ouch. Do i need working speedo for MoT as i have a GPS which will display speed?
 
Last edited:
Meter on AC? At least it is reading something. There's a few videos on YouTube showing a 9V battery and an LED bulb. You connect those in and spin the wheel by hand. If the bulb pulsates....
 
Steve E said:
Found plug. Put a meter across it with engine running out of gear 0 Volts. Put into gear (on centre stand) meter across pins is constant 1.64 Volts. I presume that this means the sensor is kaput? New sensor from motorworks is £160. Ouch. Do i need working speedo for MoT as i have a GPS which will display speed?
Click to expand...
The sensor will generate a series of pulses, several per revolution. The speedo/combo unit will be counting the number of pulses and converting that into the speed.
Seeing 1.64 volts on a multimeter will not be conclusive to anything. Using an oscilloscope or similar to see the pulses would be more useful.
The debris drawn to the sensor's magnet indicates a potential issue with your final drive and will have stopped useable pulses being generated. I would pull it again and check to make sure it is not covered again 😉
 
Agree with what Magwych said.
I believe there are 2 types of sensor, one you can test for voltage, other you cant as it has to be connected to complete the circuit.
I also had lots of tiny metal swarf on mine when i removed it (and oil had been drained before). Its a magnetic head on the sensor so likely its been there ages
 
Please tell me I wasn't the only one who saw the thread title and thought the OP's budgie smugglers had let him down........................... :nenau :D
 
Steptoe said:
Oh dear. Why ?
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I was going to re-finish the bottom of the fork as it a bit corroded. When I undid the screw that held it in, the screw sheared and when I with drew it, the sensor fell apart (probably one of the reasons the ABS went kaput). Would leaving the front sensor in place have kept the speedo working? I understood the front sensor was for the ABS only and not for the speedo. Am I wrong?
 
My experience of what you described turned out to be a faulty rear ABS sensor. 90 odd quid from BMW and an easy repair I thought.
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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