ABS Flashing servo

[Howard J]

2004 GSA with servo ABS.

Recently I had the warning triangle showing, but a new bulb solved that. I was out today and the warning triangle came on after braking heavily together with the ABS light rapidly flashing, I stopped and turned off and started ok with no lights on, then after braking the same again, stopped again and turned off and on …… this time I just used the back brake and all ok until I used the front brake, then ABS rapidly flashing again.
There seems to be plenty of fluid in the front master cylinder reservoir….not taken the top off yet, but I can see plenty of fluid when moving the bars. Braking seems to work ok.

Any ideas? Thanks

 

[Ian J Hartley]

The front master cylinder and foot brake master cylinders are only the control circuits. These levels never alter unless you have a leak.

The front and rear brake operating circuit reservoirs are on the servo unit under the fuel tank. These levels decrease with brake pad wear.

 

[Ian J Hartley]

To Check the servo motor/pumps.

Ignition on.

Pull front brake lever. The pump should run continuously. The tone should change with brake lever pressure.
Release lever, pump should stop.

Press foot brake lever and keep it pressed. The pump should run for a short period then stop.

If this works then you may well have a front ABS sensor faulty.

Ian

 

[Howard J]

The front master cylinder and foot brake master cylinders are only the control circuits. These levels never alter unless you have a leak.

The front and rear brake operating circuit reservoirs are on the servo unit under the fuel tank. These levels decrease with brake pad wear.

View attachment 460027

Thanks Ian, I would say it’s either numbers 5 or 6 on the list …… ABS flashing quickly ?

 

[Howard J]

To Check the servo motor/pumps.

Ignition on.

Pull front brake lever. The pump should run continuously. The tone should change with brake lever pressure.
Release lever, pump should stop.

Press foot brake lever and keep it pressed. The pump should run for a short period then stop.

If this works then you may well have a front ABS sensor faulty.

Ian

Thanks Ian, just went outside and tried it, exactly as you have described above ….what are my options? Remove ABS?

 

[Ian J Hartley]

That prooves that both the motor/pump units are operating.
It also prooves that the pressure sensors inside the servo unit are also working.

My guess would be that the front ABS sensor is likely to be faulty. Though this should have have been picked up when it checks it’s self during ride off.

If you can’t see anything obviously wrong with sensor and wiring, and the gap to the front ring is OK and the front ring is undamaged, then at this stage all I can suggest is try to replace the front sensor. But this is no guarantee it will clear your fault.

Ian

 

[Howard J]

Thanks Ian , maybe not as drastic as I first thought then, I’ll check what you have suggested before I go down the ABS delete route …. Seems to make sense if the ABS unit is ok

 

[Udders]

It’s clearly scrap material.

I’ll give you £250 for the tank!

 

[Pete.]

I have a front sensor if you need one. It's for a 1100S but it will probably be compatible.

 

[Howard J]

I have a front sensor if you need one. It's for a 1100S but it will probably be compatible.

Thanks for that, although I think there are a few different ABS type sensors for the 1100/1150 range so doubtful that they would fit, I’ll check it out