iABS problem, appreciate suggestions

[PETDOC]

High resistance in the light bulb circuit could (and should) trigger the general warning light from iABS unit, but I seriously doubt that it would put the system (front or rear) in residual mode.
My main complaint about iABS is that it makes you think about brakes, which is really not a good thing to do while riding.
Keep us updated.

I agree with both sentiments you expressed. I understand how any rear light, original 1157 dual filament bulb or aftermarket LED, will trip the lower BRAKE WARNING light. I have experienced that phenomenon with both types of rear lights in my '04 1150 GS, and in both instances the lights were fully functional. One of the filaments blew in the 1157 bulb a couple of weeks after the warning light was tripped by the increased resistance of the failing filament, but the LED never demonstrated a malfunction. I do not, however, understand how an aftermarket LED that had or developed abnormal resistance can illuminate the ABS (upper triangle) warning light and record a specific failure as measured by the GS911. I have found both low pressure in circuits and defective rear ABS motor faults, but always listed as No Longer Present. The fact I have gone 150 miles with the original bulb (sans LED) and not seen any warning lights gives me the slimmest glimmer of hope, but as stated I will not exhale until at least 500 miles and then only partially exhale. Perhaps after several thousand miles I'll breath normally again.
Your comment regarding the distraction is absolutely correct. I've ridden several hundred thousand miles over nearly 5 decades and, although admittedly lucky in the formative years, have avoided any serious accidents because of a practiced focus on what's going on around me. Lately, however, I find myself frequently looking to see when the warning lights illuminate, this despite the fact that my brakes have never failed to function normally. Last statement excludes certainty the ABS is functional when upper ABS light is flashing.
I have asked Advrider.com poster, who lives in Norway, if he is aware specifically of an LED brake/running light triggering an ABS failure warning light and not just the lower brake failure light.

 

[PETDOC]

I stopped by local BMW shop and after hearing my lengthy story the parts manager, who himself owns an 1150 GS, said it didn't sound like a faulty ABS module, never heard of an LED triggering the ABS warning light or activating module fault codes, but was suspicious of a loose or faulty ground wire.

Does anyone know what color the ABS module ground wire is on the 1150 GS with servo brakes and where it might attach on the frame?

 

[codcutter]

Does anyone know what color the ABS module ground wire is on the 1150 GS with servo brakes and where it might attach on the frame?

According to my Clymer manual, it's a brown wire that earths on the gearbox

 

[AntonLargiader]

Nothing earths on the 1150 gearbox. There's ground point on the left side of the engine, though, just forward of the gearbox.

 

[PETDOC]

Nothing earths on the 1150 gearbox. There's ground point on the left side of the engine, though, just forward of the gearbox.

Is it hidden by the plastic cover over the starter motor?

 

[AntonLargiader]

No, on top... left side, toward the rear. Basically just in front of the negative side of the battery.

 

[PETDOC]

No, on top... left side, toward the rear. Basically just in front of the negative side of the battery.

Anton, thanks.
Now sans LED tail light I've covered 210 miles on 3 rides without illuminating warning lights. It is totally illogical to me that the tail light could have triggered ABS faults, so currently I still don't believe it did. My plan is to check the ground attachment and the continuity of the ground wire to the pin in the electrical attachment at the ABS module. I'll do this when the ABS warning light illuminates or at the time of my next brake fluid change, whichever comes first.

 

[happy wanderer]

Anton, thanks.
Now sans LED tail light I've covered 210 miles on 3 rides without illuminating warning lights. It is totally illogical to me that the tail light could have triggered ABS faults, so currently I still don't believe it did. My plan is to check the ground attachment and the continuity of the ground wire to the pin in the electrical attachment at the ABS module. I'll do this when the ABS warning light illuminates or at the time of my next brake fluid change, whichever comes first.

It actually makes sense. An LED and a light bulb have different impedance in the circuit which is monitored by the ABS. It "thinks" the reduced impedance is a blown or failing bulb so it throws a fault code. Light comes on...

 

[kioolt]

It actually makes sense. An LED and a light bulb have different impedance in the circuit which is monitored by the ABS. It "thinks" the reduced impedance is a blown or failing bulb so it throws a fault code. Light comes on...

I believe that you meant to say increased impedance. An LED has relatively high resistance when compared to a standard tungsten filament light bulb. I can see the LED causing a taillight or brake failure light fault but not an ABS fault as the OP said. What reason would the engineers at BMW have for disabling a otherwise working ABS brake system because of a bad bulb?

 

[bc1100s]

I believe that you meant to say increased impedance. An LED has relatively high resistance when compared to a standard tungsten filament light bulb. I can see the LED causing a taillight or brake failure light fault but not an ABS fault as the OP said. What reason would the engineers at BMW have for disabling a otherwise working ABS brake system because of a bad bulb?

I was always under the impression that an LED had less resistance than a standard filament bulb hence the quick flashing of an aftermarket LED turn signal without the addition of an in-line resistor. Further, not sure the ABS is actually disabled (I may be wrong here) but the warning light seems like an excellent way of telling you that you have an issue of some sort...like a burned out bulb.

 

[kioolt]

I was always under the impression that an LED had less resistance than a standard filament bulb hence the quick flashing of an aftermarket LED turn signal without the addition of an in-line resistor. Further, not sure the ABS is actually disabled (I may be wrong here) but the warning light seems like an excellent way of telling you that you have an issue of some sort...like a burned out bulb.

No, an LED definitely has increased resistance and also the resistor is not put in-line with the LED, it is put in parallel to the LED. Modern electronic flashers are designed to give the quick flash when a blown bulb (high resistance) is detected. That is why an LED without the parallel resistance will cause it the hyper flash.

The OP said he had residual braking in the rear brakes on some occasion. BMW engineers designed the ABS control board to monitor the taillight and brake bulb and to also give warning if one is bad. If the taillight bulb blows, the control board will give a fault light (can't recall the actually light pattern) AND light the brake bulb up at partial intensity to simulate a taillight. If the brake light bulb blows you just get the warning light.

 

[kioolt]

Let me add something about the resistance of an LED bulb. I'm referring to LED bulbs that are designed to be operated on 12v. These actually have resistors built into them. The reason for this is that an LED actually has a low resistance when lit and the resistor is there to limit the current through it so that it does not burn out. The total resistance of the built-in resistor and LED is higher then a standard bulb. That is why a parallel resistor is needed to get the resistance down to the level that the flasher will operate correctly.

 

[PETDOC]

As a point of clarification I had installed a 40 LED TAIL/ABS Brake light (http://www.motoelekt.com/lighting.htm) several years ago. The light was nothing short of fantastic, but eventually always triggered the lower Brake Warning light despite being fully functional. I purchased a new LED light. After a relatively short time, at random intervals and never at start up, my lower Brake Warning light illuminated steady and the upper ABS FAILURE light would illuminate at 4 Hz. The rare times I noticed the sequence of the illumination it was lower Brake Warning light followed very shortly by upper ABS Failure light. Brakes always worked fine (possible exception is ABS; never tested). When the engine was restarted the warning lights were always off for a few miles to >100 miles. Multiple ABS faults were recorded and reported by a GS911, but were always No Longer Present. The Defective Tail light fault was also recorded, despite a normally functioning LED. I have done numerous things to correct the presumed ABS problem and fear my ABS module is failing. Recently I removed the LED, replacing it with the original dual filament light bulb and have ridden 210 miles without the illumination of either warning light. There has never been a question in my mind regarding the reason for the 2 LED lights triggering the lower Brake Failure light. Obviously the measured impedance/resistance(?) drifted outside the allowable range set by BMW.
Whether the Second LED triggered the ABS Failure light is the question. It seems impossible. Even if I never see the ABS warning light again l'll be uncertain if the LED was the problem. The only way to verify the LED as causal will be to ride 1,000 miles without warning lights then recreate the problem by replacing the dual filament bulb with the LED. Having said that, I sincerely hope by some never to be known mechanism the LED did trigger the ABS warning light.

 

[cele0001]

The only way to verify the LED as causal will be to ride 1,000 miles without warning lights then recreate the problem by replacing the dual filament bulb with the LED. Having said that, I sincerely hope by some never to be known mechanism the LED did trigger the ABS warning light.

It wouldn't be verification, but probability would increase.
I still don't buy it. I would buy piece of trash stuck at the valve (and moved), as more likely cause. Time will tell..

 

[bc1100s]

No, an LED definitely has increased resistance and also the resistor is not put in-line with the LED, it is put in parallel to the LED. Modern electronic flashers are designed to give the quick flash when a blown bulb (high resistance) is detected. That is why an LED without the parallel resistance will cause it the hyper flash.

The OP said he had residual braking in the rear brakes on some occasion. BMW engineers designed the ABS control board to monitor the taillight and brake bulb and to also give warning if one is bad. If the taillight bulb blows, the control board will give a fault light (can't recall the actually light pattern) AND light the brake bulb up at partial intensity to simulate a taillight. If the brake light bulb blows you just get the warning light.

I now consider myself newly educated in the ways of LED light bulbs. Thanks for the clarifications!

 

[happy wanderer]

No, an LED definitely has increased resistance and also the resistor is not put in-line with the LED, it is put in parallel to the LED. Modern electronic flashers are designed to give the quick flash when a blown bulb (high resistance) is detected. That is why an LED without the parallel resistance will cause it the hyper flash.

The OP said he had residual braking in the rear brakes on some occasion. BMW engineers designed the ABS control board to monitor the taillight and brake bulb and to also give warning if one is bad. If the taillight bulb blows, the control board will give a fault light (can't recall the actually light pattern) AND light the brake bulb up at partial intensity to simulate a taillight. If the brake light bulb blows you just get the warning light.

A blown bulb is high resistance? An open (blown filament) bulb has NO (infinite) resitance last time I measured one.

 

[kioolt]

A blown bulb is high resistance? An open (blown filament) bulb has NO (infinite) resitance last time I measured one.

I will stand by my statement that a blown bulb is high resistance since infinite resistance is also high resistance to most people with technical training like me. But NO resistance = zero resistance ,not infinite resistance.

 

[cele0001]

A blown bulb is high resistance? An open (blown filament) bulb has NO (infinite) resitance last time I measured one.

Infinite is really, really high. Infinite is a relative term. Resistance of air is finite, so blown bulb has high resistance. Most multimeters don't show readings (or show 0, some show OF for overflow) when resistance is over a certain threshold.

 

[kioolt]

Infinite is really, really high. Infinite is a relative term. Resistance of air is finite, so blown bulb has high resistance. Most multimeters don't show readings (or show 0, some show OF for overflow) when resistance is over a certain threshold.

I've used many brands of meters in my career and at home. My main meter here at home now shows O.L. when the resistance is too high for it to read. When I see this I know that the resistance being measured is out of range (on the high side) of what the meter is capable of reading. It is not NO resistance. When the meter is turned on and the probes are not connected to anything, even each other, it shows O.L. Again this does not mean NO resistance. It doesn't really mean infinite resistance. It means the resistance is higher then the meter is capable of reading. I've used other meters that will show 1.999 when the reading is out of range.

 

[jeff488]

For my practical purposes, two ohmmeter leads touching is zero resistance and the resistance across a parsec of space is infinite.

With enough technical one-upsmanship perhaps the number of angels that could wheelie on the head of a pin could be determined.
That would be useful.

I believe a ride is in order.