1150 adv ABS woes- no come back, need help ............

[Ed209]

Hi guys, searched the many many servo/abs problem posts but nothing helps. The bike is a 2003 gs adv with servos and abs. When I switch ignition on both lights flash as normal for a few seconds then the bottom one goes out leaving the top one flashing slow. I ride off and the top one goes out too. All ok. As soon as I use the brakes (either one) the top one flashes faster and the bottom one comes on and stays lit with the brake on, Soon as i let go it goes back to the top one flashing slowly. This is the same with just the ignition on. When i apply the front brake the servos whine as normal. When I apply the back break there is no whine but same flashing lights.

New oddysey battery recently and starts perfectly. When riding the bike the front brakes work fine and have normal breaking. I dont normally use the back brake and just tried it but no whine and it seems residual braking at best. I read about a microswitch on the back brake but mine seems to just have the plunger into the cylinder and no switches.

I did a short video of the warning lights but have no idea how to post on here

Any help apprieciated

Steve

 

[plrb]

Lights

Check brake fluid / worn pads, ~ had same on mine, cured with new front pads despite being nowhere near limit. FYI mine uses 3 sets rears to 1 set fronts, so check rear first.

 

[Ed209]

Even if pads were down wouldnt I still get servo whine on application of back brake? Or would the system recognise low pads and throw up a fault causing the servos to stop working on the rear? Cheers for the reply

 

[Ian J Hartley]

The micro switch is just under the lever pivot point. If it isn't giving an audible click when you depress the lever, it could be either broken or full of crud and need cleaning.

Your symptoms are residual braking and it sounds like the rear circuit.

Ian

 

[Jamieboy]

I had fault lights etc and my bike put the rear circuit into residual breaking when there was a fault with my rear abs sensor. It was the cable, as I got it to work again briefly by 'jiggling' the cable. Got a second hand sensor and cable from motorworks and it has been fine ever since.

 

[Fanum]

The micro switch is just under the lever pivot point. If it isn't giving an audible click when you depress the lever, it could be either broken or full of crud and need cleaning.

Your symptoms are residual braking and it sounds like the rear circuit.

Ian

Agreed......the microswitch is in a fairly vulnerable lodcation and they do get crudded up.

A good squirt of WD40 or brake cleaner followed by WD40 should sort it.

As Ian says, you should be able to hear a distinct but small click when you operate the lever

 

[Ed209]

Thanks guys, all good info. Just had the rear brake pedal assembly apart and found the switch. Does look ok and activates the brake light ok so think it should be fine. Does the system detect low rear pads? and could that trip residual braking? Think it must be the rear circuit as front brakes work fine and they activate the servos as I hear the whine. When I press rear brake the servos dont make any noise.

 

[Fanum]

Thanks guys, all good info. Just had the rear brake pedal assembly apart and found the switch. Does look ok and activates the brake light ok so think it should be fine. Does the system detect low rear pads? and could that trip residual braking?

No, it doesn't, and couldn't.

Check the ABS ring though, and the sensor.......they need to be clean and obviously need to be lined up properly.....there are probably some threads here about that with a lot more info.

 

[Fanum]

By the way, replace your brake bulb as well.......it's a standard 380 bulb.


Yes, yours is working, but BMW were fairly clever on that, and if ONE of the two filaments failed, the bike uses the other filament to do BOTH jobs (running light AND brake light)

So although it looks like it's working (and in fact, it IS working) the system tells you a filament is blown through the lights flashing......I can't remember the frequency or combination of those lights in the case of a blown filament, but it COULD be that, and for the 40p that a 380 bulb might cost you, it's worth eliminating

 

[Ed209]

No, it doesn't, and couldn't.

Check the ABS ring though, and the sensor.......they need to be clean and obviously need to be lined up properly.....there are probably some threads here about that with a lot more info.

Yeah Ill think Ill have to do that. I dont use it much and its been sat in the garage a couple of months. My guess is a knackered sensor as nothing should have moved as I havent had anything off. My BMW car is sick at the moment so need that fixed. Ill have to wait till the car sorted or ill have no transport.

 

[mspenz]

That's interesting info about the bulb and a good one to remember

It would also be worth flushing / bleeding the brakes and metering circuits if you haven't done so already as those servos can be quite sensitive and don't like the combination of dirty fluid and condensation!

 

[Madmountainman]

I'm surprised no-one's mentioned it yet… servoectomy. It will solve the problem.

 

[mspenz]

Did you get this fixed?

I'm not going to crash your post with my new brake problem which has started today so I'll start another thread!!

 

[Ed209]

hi mate, not been on here for a while as I have had more pressing famliy matters. i read your post with interest but as you have no warning lights i think. just going to start looking at this again as mine still isnt working. i think its more serious but before wasting the time of the guys on here i am gonna replace the rear bulb. I assumed that if your tail light and your stop light still both work then the bulb must be ok and it couldnt be that. Now i know that even if one filiment goes then you still get both lights but the system will still see an error. Ill have another go on it now and posts results. Thanks for all the help guys.

 

[Fanum]

hi mate, not been on here for a while as I have had more pressing famliy matters. i read your post with interest but as you have no warning lights i think. just going to start looking at this again as mine still isnt working. i think its more serious but before wasting the time of the guys on here i am gonna replace the rear bulb. I assumed that if your tail light and your stop light still both work then the bulb must be ok and it couldnt be that. Now i know that even if one filiment goes then you still get both lights but the system will still see an error. Ill have another go on it now and posts results. Thanks for all the help guys.

There is room inside the rear lens unit to gaffa tape a spare bulb wrapped in thin bubble wrap or foam.......Of course, if you do this, it absolutely guarantees that you'll never ever need it

 

[Ed209]

Theres room for sandwiches in there too mate but a good tip lol. Just tried another bulb but not that. Still scratching my head. Definately something on the back brake and servo related. Cant hear a servo whine on the back brake at all and it seems on residual braking. might just have to take it to a garage as this servo abs malarky is a bit much for me

 

[Ed209]

Anyone got a link to a page explaining how the servo abs works on these things? not sure what is signalling what? whether its electrical or a physical brake pressure problem? Dont want to be buying lots of bits trying to find the problem?

 

[Ed209]

Trying to work out how the rear brakes work and what exactly sends a signal to the servo unit.

1. Does the rear brake micro switch just operate the brake light or does it send an 'on' signal to the brake system?

2 Does the servo system compare the signal from the micro switch and the pressure applied at the rear master cylinder? If it is sensing pressure from the rear cylinder but no signal from the switch, or vice versa does it show an error light?

3 If the rear master cylinder has gone would I get limited rear brake or none at all?

the reason for question 3 is that when I took the rear reservoir cap off then pumped the rear brake pedal there seemed to be a squirt of fluid back into the reservoir? always thought this was a sign of the seals gone in the cylinder? That might be my problem mebbe?

 

[Flipfly]

One small pipe and it could all be over......servoectomy!!!

I did one before I had any issues, my brakes are brill

 

[Ed209]

Yeah hearing a lot about taking it out. Do you lose abs? This is the only bike ive had tricky/servo/abs/linked brakes on and they still seem strange. Hows the brakes on your without it all?