Speedo sensor failing symptoms

Bendy toy · Dec 15, 2016

I had a few glitches some months ago which were cleared by cleaning the electrical connector and sensor head. The latter clean when removed. Now I get the brake warning light and no speedo for a couple of miles after engine start. The speedo then wakes up and works normally. Stop to reset the ignition (off-on) and it does the same.

I assume its telling me the speed sensor is fecked, but before I shell out for a new one. Is that what they normally do when failing? I'd have expected the speedo to stop completely or work, but not both.

comberjohn · Dec 15, 2016

That's what mine did. Time to put your hand in your pocket, bendy.

UturnTony · Dec 15, 2016

Bendy toy said:
I had a few glitches some months ago which were cleared by cleaning the electrical connector and sensor head. The latter clean when removed. Now I get the brake warning light and no speedo for a couple of miles after engine start. The speedo then wakes up and works normally. Stop to reset the ignition (off-on) and it does the same.

I assume its telling me the speed sensor is fecked, but before I shell out for a new one. Is that what they normally do when failing? I'd have expected the speedo to stop completely or work, but not both.

Rear ABS sensor faulty.

If the control module is getting a signal from the sensor but that signal is not valid the CM will wait a while (couple of miles perhaps)
and if still nothing sensible is received it will switch to using the front sensor to calculate a speed reading.
If you disconnect the sensor completely the CM will switch immediately (because there is no sign whatever of a sensor) and not wait so the speedo will register straight away.

Bendy toy · Dec 15, 2016

Aha! Thanks. Time to dust the moths away from my debit card.

Thanks folks.

Part ordered from Motorworks.

Bazzer66 · Apr 20, 2017

How did you get on Bendy? My 2007 GSA has exactly the same issue along with a red ABS warning light. I couldn't find any obvious signs of damage to the sensor or cable so dropped the bike into Brizzle Dealer to be told it needs an ABS module - at a whopping cost of £1300 fitted! Feck me! :blast

comberjohn · Apr 20, 2017

While the ABS can be an issue on the SC, I wouldn't jump to conclusions just yet. Dealers have been known to be wrong, bless them.
Are the symptoms, loss of speedo and ABS light, intermittent or all of the time?
If only now and again it's probably the sensor. If the light is on constantly then it's probably the ABS unit.
There won't necessarily be an sign of damage on the sensor or its cable. Like any electrical component, sometimes they just stop working.

Bazzer66 · Apr 20, 2017

Good point Bendy. The speedo remains at zero until about 10 mins into a ride but the brake light remains ON throughout - although brakes appear to function normally?!

Lentarn · Apr 20, 2017

Just had the same problem occur after a week away off the beaten track. ABS light flashing, 'brake failure' light on and then after a few restarts the speedo wouldn't kick in until a few miles in. I checked all the obvious stuff like dirty sensor, frayed cables, electrical contacts at the battery etc and then called bmw out who diagnosed and confirmed rear sensor fail. My brake failure light and flashing ABS were on all the time, speedo was intermittent

I got this done before going to the dealer because I knew the cost of the ABS module. Surprise surprise, when they got it their first comment was that I probably needed an ABS module, I ran them through all the checks I'd done and the fact that emergency tech had confirmed it was a rear sensor fault. I'm not saying it isn't your main module but don't be fobbed off with 'you need a new ABS module'

Bear · Apr 24, 2017

Bazzer66 said:
Good point Bendy. The speedo remains at zero until about 10 mins into a ride but the brake light remains ON throughout - although brakes appear to function normally?!

When you say the brake light is permanently on do you mean the brake light at the back of the bike or the warning light? If the former then there are four possibilities, which GS-911 will help with. Failed or maladjusted front brake switch, ditto rear brake switch or a break in the wiring (the brake switches are normally closed so a broken wire looks like a brake lever or pedal being pressed). If it's the warning light that's permanently on, is it solid, flashing slowly or flashing quickly?

Pukmeister · Apr 24, 2017

Bendy, your symptoms sound identical to when my rear sensor failed ( a replacement cured it.)

Speedo sensor failing symptoms

Bendy toy

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comberjohn

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UturnTony

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Bendy toy

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Bazzer66

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comberjohn

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Bazzer66

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Lentarn

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Bear

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Pukmeister

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