iABS problem, appreciate suggestions

[PETDOC]

iABS problem, appreciate suggestions
I may be experiencing a failure of the iABS on my '04 1150 GS. I purchased the bike new and have done all maintenance and repairs during 48,000 miles of trips covering 44 of the States and Canada. Using funnel technique brakes were bled annually except for 2012 & 2013. Broke a few bones late 2011 and early 2012 so since November 2011 I've put less than 1,000 miles on the bike. It has always been stored in conditioned space, I changed out my brake lines for Speigler SS lines in 2010 and currently have a 2 1/2 year old Odyssey battery that is recharged using Odyssey charger every time voltmeter drops below 12.8V.

My problems began almost 1 year ago with the upper Brake Failure light (aka, ABS Warning light) coming on within 5 to 20 miles into a ride. The brakes worked fine and if I stopped the bike and restarted it the light never came on for the remainder of the trip. This happened on 3 separate rides. Less often during a ride the Brake Failure light began flashing at 4 Hz and the lower General Waning light (triangle) illuminated. When this happened the front brake worked fine but the rear brake had only residual braking. Stopping and restarting the bike has always solved the problem.

I checked the micro switches (both clicking) and front brake lever (not touching), pulled and cleaned the rear ABS sensor and changed the brake fluid in both the wheel and control circuits. Several days ago I went for a 70 mile ride. For the first 20 miles, which included several intentional sudden stops from both low and high speeds, everything worked fine. At the 20 mile mark the Brake Failure light came on, but brake function was normal; I could hear servo motor when I used either front or rear brake. After stopping the bike for about 30 seconds I turned on the ignition, the warning lights went through the proper sequence, I started the engine and as soon as I started rolling the Brake Failure light, which was flashing at 1 Hz went out. Rode 30 miles without incident then stopped for 45 minutes. Bike started fine, but within 5 miles the Brake Failure light was flashing at 4 Hz and the General Warning light was illuminated (no flashing). Again front brake was fine and rear had only residual function. I stopped and restarted. When I turned on the ignition the General Warning light went off, but the Brake Failure light never cycled to 1 Hz. When I started the engine the Brake Failure light continued to flash at 4 Hz, the General Warning light was not illuminated and I had only residual braking both front and rear. I assume this occurred because I started the engine with the Brake Failure light flashing at 4 Hz vs 1Hz. A short time later the General Warning light suddenly illuminated and once again the front brake worked fine, but rear was still only residual braking.
The following day the brake light sequence was normal on start-up

Looking at the codes:
1. Brake Failure (ABS warning) light ON, General Warning light OFF-- only residual braking in both circuits or ABS function has been deactivated.
Every time I had this situation both brakes worked fine and I could hear the servo pump when I activated either the front or rear brake. I assume my ABS was deactivated?? However, in each instance stopping and restarting the bike solved the issue.
2. Brake Failure (ABS warning) flashes at 4 Hz, General Warning light ON-- at least 1 brake circuit in residual braking function mode.
This would agree with what I experienced and it was my rear brake.
3. Brake Failure (ABS warning) flashes at 4 Hz, General Warning light OFF-- only residual braking available in both circuits. Self diagnosis not completed.
This happened when my Brake Failure light would not cycle down from 4Hz to 1Hz and I started the engine, but after a few minutes of riding the General Warning light came on and I once again had a normally functioning front brake.

I ran a GS911 using the most recent Beta version of software. It indicated 3 faults, but stated they were no longer present- low pressure in front and rear wheel circuits (17181 & 17433) and defective front brake switch (17918). I erased the codes and ran through all the other available tests for the ABS. Everything checked out. I then rechecked for faults and there were none recorded. I assume the recorded faults that were no longer present resulted when I had bled the brakes.

. I have a dash voltmeter which at rest is 12.81V, with ignition on it drops to 12.20V and when I hit the starter it momentarily drops to 10.96V. I spoke with a mechanic who told me if the voltage drops below 12.6 the ABS will not initiate; however, it doesn't seem like it could be a battery issue because the faults all develop several miles into a ride and the voltmeter is always in the mid 13V range when the engine is running.

Based on reading many posts regarding iABS failures my current plans are to:
1. Replace battery with Panasonic LCX 1220P. Had one for years and was very, very happy with it's performance.
2. Remove aftermarket rear LED brake/running light. Brake light test with GS911 was normal
3. Remove rear brake lever, clean micro switch and detach, clean and reattach electrical connector. GS911 test indicated switches were good.
4. Replace rear brake pads. Inner rear pad has 2.4 mm left, which is still considered good ( normal > 1 mm), but I'll try anything right now.
5. Re-torque the rear wheel lug nuts and check the rear ABS sensor gap.
6. Check the rear electrical brake wiring for a crimp. Again GS911 brake light test was normal.

Any other suggestions are appreciated. I don't know if I should take the normal readings from the GS911 as a sign that it's not likely to be the ABS module failing or as a sign that it is a module failure.

[MotEng]

Dear Petdoc,
which alternator is fitted on your bike Bosch or Denso?
You say while riding charging voltage is in the 13sh! Does it go over 13,90v or not?

I would run a load test on the battery, also would check if alternator is charging properly, plus  i would gave the alternator belt a good look!

[PETDOC]

MotEng,
 Interesting that you mention the alternator. It is the original Bosch alternator. I think, but am not certain that I used to see the dash mounted voltmeter on occasion hit 14v, especially when I had the accessories turned off (heated grips, PIAA lights). When I saw the voltage around 13.4v the thought occurred to me that it was lower than I had remembered, but it seemed 13+ volts would have been adequate for the ABS to function. I now wish when I was hitting the brakes to check them after the flush I had concentrated more on the voltmeter vs the warning lights.
 I have a nearly new Bosch alternator purchased from a wrecked 2004 1150 GS with only 2000 miles on the odometer. I'll swap out the alternators and take my original one over to an alternator shop to be tested.

[MotEng]

As i am concerned there are two types of alternators one produces 700 watts which is fitted on ABS bikes and one 400 watts for non abs bikes! I would be careful which alternator i should purchase.
Another issue, did you ever noticed the drop in voltage, on your volt meter, when you where hitting the brakes and the ABS would come on?
Anyway the minimum voltage you should see at neutral and engine at tickover of 1100rpm is 14,00 volts!
I also mentioned the alternator belt! I replace it at max of 40000km instead of 60000km which is a factory service limit.

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[PETDOC]

As I recall you are correct there were 2 alternators with significantly different output. My spare came from an identical 2004 1150 GS with servo iABS brakes, but I'll check the part number before swapping out alternators.

[PETDOC]

I've had some second thoughts on my early explanation for and dismissal of faults the GS 911 reported. They were reported as no longer present and I assumed they were caused by the recent brake bleed. I'm still convinced the low pressure in the front and rear wheel circuits were brake bleed associated, as the ignition is on as I bleed the wheel circuits. The front brake switch fault may have merit.
My logic is as follows:
1. Detectable malfunction has been in rear brake-residual braking only.
2. Fault appears well into ride and clears with restarting the bike.
3. My brakes are partially integrated; therefore, the front brake also activates the rear.
My conclusion being I need to really inspect the front brake switch and wiring from it to rear brake for defect.

[PETDOC]

I have:
1) replaced what I believe to be a perfectly good 2.5 yo Odyssey with a new Panasonic battery
2) re-torque rear wheel bolts, cleaned and checked gap on rear ABS sensor
3) cleaned and checked gap on front ABS sensor
4) replaced what I believe to be perfectly good front and rear microswitches with new switches and cleaned the connections with electrical contact cleaner. Continuity with old and new switches tested same with multimeter.
5) cleaned the connections of the ABS sensors with electrical contact cleaner
6) split the wiring harness for the ABS module from above to below the battery box and examined every wire with a magnifying glass-no observed abnormalities
7) topped up already full, recently flushed wheel circuits with DOT4
replaced the rear LED brake/running light with OEM dual filament bulb

The only possible abnormality I detected during my examination of various wires was the connection for the rear ABS sensor under the right side of the rear of the front seat wasn't completely seated; it moved about 1/8 to 1/4" when I pushed it together.
 I have ridden 275 miles during 3 trips. The brakes work fine and no warning lights are flashing. I plan to replace the OEM rear brake/running light dual filament bulb with the aftermarket LED. My guess is the issue was with a brief disconnection of the incompletely seated rear ABS sensor connection or a dirty connection of one of the microswitches.
My question now is if it was a random quick disconnection/reconnection of the rear ABS sensor that triggered the warning lights and failure of the rear brake why was no fault recorded?