Brake warning lights flashing - what's up?

[RichardSpag]

A question for the collective brain that is BMWSportTouring - just recently the red warning triangle and "brake failure" lights have started to flash (out of step from each other)after I have travelled about a mile and stopped (typically at a set of traffic lights). If I turn off the ignition and then turn it on again, the lights will often stay off for the rest of the day. Brake feel is normal - so is this a potential ABS problem? The odd thing is that this problem has only started since the colder mornings have arrived here in blighty. Could this simply be something somewhere needing a little squirt WD40 or the start of something more sinister.

 

Am I likley to get the "WTF" and flashing "£" signs appearing anytime soon on the display?

 

Thanks in advance

 

Richard

[dirtrider]

Morning Richard

 

As a rule, on your 05 with the IABS system, when you have the ‘Gen light “and” ABS light flashing alternately at 1Hz’ that says the “Fluid level in Intergral ABS master cylinder reservoir’s “under gas tank” are too low. Or in rare cases the IABS system voltage is too Low.

 

Probably the place to start is to remove the gas tank then remove the covers on the IABS controller’s reservoir’s, then make sure the reservoir’s are both full.

 

If all OK on the under seat reservoir’s then make sure your battery and charging system are up to par.

 

If you can get hold of a GS-911 you can probably pull the stored failure codes to see why the IABS system is flashing at you.

 

[Hall Vince]

Sounds like it could be a tired battery. Is it original?

[RichardSpag]

The battery was new three months ago and the alternator belt is not slipping. Each day the bike gets a 104 mile round trip at motorway speeds - so low charge probably not an issue. But I have no means to measure this to confirm that this actually is the case.

 

Thanks for the input

 

Richard

[RichardSpag]

Thanks Dirtrider -I'll give that a go. If the levels are getting low enough to trigger a warning, does that mean that there is a fluid loss inherent with the operation of the system? The brake circuit has not been bled for a couple of years - would keeping to the change schedule have compensated for any fluid loss under normal circumstances and therefore avoided the warnings being set off?

 

Cheers

 

Richard

[Ken H.]

This is a good example of where the GS-911 tool shines. It would be able to pull the stored trouble codes for you. Do you know anyone who has one? Or better yet, consider buying one.

[Sailorlite]

I'd take a quick look at the front ABS sensor wire to see whether it's been rubbing on the brake rotor (due to poor routing).

[babalueb]

Mine started to flash when the front brake disc wore through the insulation of the sensor wire.

[dirtrider]

Thanks Dirtrider -I'll give that a go. If the levels are getting low enough to trigger a warning, does that mean that there is a fluid loss inherent with the operation of the system? The brake circuit has not been bled for a couple of years - would keeping to the change schedule have compensated for any fluid loss under normal circumstances and therefore avoided the warnings being set off?

 

Cheers

 

Richard

 

 

Hi again Richard

 

Just because the ABS controller reservoirs are getting a little low doesn’t necessarily point to a system leak. As the brake pads wear the calipers hold more fluid behind the pistons. If the reservoir on the offending end wasn’t completely filled at last brake bleed it might be just low enough now to bring the low fluid alternating light flash on.

 

The other possibility is the bake was laid over on it’s side at one time, when that happens some of the brake fluid runs out the overflow hose behind the right hand foot peg.

 

While it doesn’t hurt to check the sensor wire routing or other things a cut sensor wire won’t give you ALTERNATING flashing lights. It will give a steady on general light and a flashing brake warning light.

 

 

 

 

[racer7]

And don't let that system sit forever with old fluid. The first thing that happens as it begins to discolor is that it throws some fine particulates and the anti-corrosion properties go off. There are some very expensive parts in those 05 systems you really don't want to buy.

The 2 yr timing is also recommended by a lot of car makers but most car systems have bigger internal passages (and cheaper parts) so are as sensitive to deteriorating fluid as a small passage bike system can be. Some folks get in the habit of being as lazy about this with their bikes as with their cars- that might turn out to be very expensive with the older style system.

[RichardSpag]

Dirtrider, et al.

 

Thanks for the various comments and suggestions. I eventually chose to install a new set of front pads and new discs (the old ones were showing wear after 87,000 miles). I am guessing that this has displaced fluid back through the system and brought the fluid level in the ABS reservoir back up to a "normal" level. No repeat of the warning lights showing in the last 120 miles - so I hope we can count this as a closed case!

 

The odd thing is that the old pads that I replaced were only about two-thirds worn and the front discs only had mild wear lips on their edges - but I guess this must have been enough to displace enough fluid to bring on the warning lights.

 

Cheers

 

Richard