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Alternately flashing ABS lights (1100); If you had to guess...


DougMcK

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There's an otherwise interesting '96 R1100RT for sale locally with alternately flashing ABS lights. The seller says he's cleaned the wheel sensors but looked no further...

 

What are the most likely probabilities for this failure (and costs) for me to fix this myself? (Assume, I'm competent).

 

For instance if there's a 50% chance it's the worst case scenario, and that would cost, say, $400, to get the ABS rebuilt, then that would be very useful information to add to my thinking.

Thanks very much,

Doug

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Afternoon Doug

 

It could be as expensive/involved as needing a new/used ABS controller (check E-Bay for current prices)

 

Or as simple as an ABS re-set (not complicated or difficult)

 

Or anything in between.

 

Or-- a low dead battery.

 

OR-- just remove the ABS system & re-plumb the brake lines & have nice stopping good modulating standard braking system

 

Use the below as a somewhat guide to what might be happening (also try re-setting the ABS)

 

--the below might help point to the where to start looking--

 

 

At key-on, the two ABS lights should flash together and should continue to do so until the ABS self-test is complete (doesn't happen until you start to ride the bike away), at that time they should go out.

 

If the self-test fails, they will begin to flash alternately. The exact moment when they start to flash alternately is usually when the problem appears.

 

If_ it happens before you start the engine it is usually a system that is tested at first power-up.

 

If_ it faults when you start the engine it is usually a low battery voltage problem.

 

If_ it faults when you ride away it could be the ABS controller or possibly a wheel speed sensor.

 

Added: ABS re-set--

 

Find the diagnostic connector (located under the seat).

 

Insert one end of a wire into the middle socket of this connector.

 

Ground the other end of that wire to a (clean) metal part of frame or good ground area (make sure it stays grounded).

 

Turn on ignition. You should now see the warning lights flash alternately.

 

Hold ABS button down for about 8 seconds. The bottom ABS light will stay on, and the top one off.

 

Release the ABS button. If you have successfully reset the ABS, both ABS lights will come on. If you have failed to count to 8, or your ground is not good, the top ABS light will stay off.

Edited by dirtrider
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Module Master does a rebuild of the ABS-2 module for $350. That is possibly your worst-case outcome.

 

It could be as simple as a weak battery causing a low-voltage condition at start up. Sensor gap could be off, sensor wire could have been worn through or frayed.

 

If it hasn't been done, plan on replacing the OEM rubber brake hoses with a stainless steel kit - about $220.

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I was getting the alternating ABS lights recently on a 2 year old battery. (96 R1100RT) I've learned the ABS system is quite particular about having nice voltage. I cleaned up the battery terminals and main wires (and large wire going to the starter). Now my ABS lights flash together as they should and ABS system arms itself properly. Go for the easy fix to begin with. Dave

 

ps- negotiate $500 off the price for an expensive ABS rebuild

Edited by Dave P
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The low-voltage issue is well known. It doesn't happen a lot with my 1999 RT, but often enough that I fitted a switch inside the fuse box. If the alternating lights blink, I pop the seat, pull the cover off the fuse box, flip the switch, and go through the drill to clear it. Much more convenient than carrying a jumper wire and finding a good ground connection.

Edited by Selden
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The low-voltage issue is well known. It doesn't happen a lot with my 1999 RT, but often enough that I fitted a switch inside the fuse box. If the alternating lights blink, I pop the seat, pull the cover off the fuse box, flip the switch, and go through the drill to clear it. Much more convenient than carrying a jumper wire and finding a good ground connection.

 

The low-voltage fault on the R1100RT (and all other ABS-2) is a self clearing fault. As soon as you turn off the key, the low-voltage fault is gone - no jumper wire, ground the maintenance wire required. That switch is convenient if you are having other ABS faults that don't clear on their own.

 

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Morning Dave

 

If I start up and ride right off my abs lights go out.--- this is normal as the ABS system does it's final (ride-off) check upon ride-away. At ride off - at appx. 3-4mph you should hear a kerrr-chinkkk sound, at that time both ABS lights should go out if all is well with the ABS system.

 

If I start up and put my gloves on, they continue to blink.---Do they go out after ride off or just stay on? If they stay on do they flash together or flash alternately? If they go off after ride-away then all is normal. (what is your bike doing????)

 

What does the ABS switch do?---Not much on the R (on the GS that switch turns the ABS off until next ign cycle). For full operation of that ABS switch look in your riders manual as that info should be in there. The switch (plus a ground wire) can be used to re-set the ABS system if it locks out.

 

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Good Morning DR,

No riders manual. Hence the dumb questions. Can't find an online version at BMW.com either. Anyway:

 

When the ABS lights stay on, they blink alternately. Left then right, continuously. If I pull over, cut engine, restart, ride off.... they go out.

 

What are my actions (other than delay ride off) that are causing the lights to stay flash?

 

When I hit the ABS button if/when lights are flashing, one stays on, then after a time they blink alternately again. I imagine that's normal? And THANK YOU for explaining that noise, another puzzler. What is that? Pads on discs as a test by the ABS?

Thanks/Dave

 

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Morning Dave

 

First off you really should find a riders manual (maybe E-Bay)-- I don't have a 1999 1100R manual either.

 

When the ABS lights stay on, they blink alternately. Left then right, continuously. If I pull over, cut engine, restart, ride off.... they go out.--- That restart being needed to clear the flashing lights kind of points to low system voltage.

 

What are my actions (other than delay ride off) that are causing the lights to stay flash?---You might try some different things right after engine start-up to see if something helps you identify where the problem is coming from. Maybe try revving the engine a couple of times right after start-up to see that forces the charging system to come on line earlier. Also try more fast idle (choke) for little longer after start-up to see if that raises the system voltage enough to stop the light flashing.

If revving the engine right after start-up helps then you might try replacing the dash generator (charging) light with a lower resistance bulb as that will bring the alternator on-line earlier after start up.

 

When I hit the ABS button if/when lights are flashing, one stays on, then after a time they blink alternately again. I imagine that's normal? ---Yes, normal.

 

And THANK YOU for explaining that noise, another puzzler. What is that? Pads on discs as a test by the ABS?---that is the ABS controller internal motor & shaft/chains exercising to set the travel limits (perfectly normal)

 

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Load test the battery, (replace if necessary) and clean up the battery connections and tighten everything up. I bet thats all you need.

 

The 2 ABS lights should flash together (as long as the bike is running and hasn't moved more than 10 feet or so). Then the "click clunk" sound DR described after 10 feet. Dave

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The low-voltage fault on the R1100RT (and all other ABS-2) is a self clearing fault. As soon as you turn off the key, the low-voltage fault is gone - no jumper wire, ground the maintenance wire required. That switch is convenient if you are having other ABS faults that don't clear on their own.

I have never seen it clear on its own, including after a 300-mile day with several stops. It's never occurred during warm weather, always in cold weather, when the battery is not putting out as much current.

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On cars I have seen the following, which may be relevant, I'm not sure... The sensor is magnetic, and it sends a pulsing electrical signal as the teeth go by. I've pulled sensors to find a small pile of metal debris on the tip of the sensor, like a magnetic drain plug. This makes the sensor put out an erroneous signal. Clean off the debris, reinstall the sensor and it starts working again.

 

I understand our bikes have shims to space the sensor, make sure to reinstall the shims, or maybe try removing a couple which would create a stronger signal? Just a hunch.

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"I have never seen it clear on its own, including after a 300-mile day with several stops. It's never occurred during warm weather, always in cold weather, when the battery is not putting out as much current."

 

Selden - When you turn off the ignition and then on again, if the two ABS lights are flashing together, then the ABS has reset. If they are flashing alternately then the fault code is not a low-voltage fault.

 

There is a specification for the ABS sensor gap to the toothed ABS ring. Instead of guessing here, the OP should read the code to determine what fault the ABS system is sending.

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I have never seen it clear on its own, including after a 300-mile day with several stops. It's never occurred during warm weather, always in cold weather, when the battery is not putting out as much current.

 

Morning Selden

 

If you have to do an ABS re-set before your ABS failure goes way then you aren't clearing a low voltage failure. The low voltage code is non latching so never needs an ABS controller re-set to go way. A simple key-off then key-on will clear it as long as the battery has sufficient voltage to properly power the ABS controller at next key-on. ( a real low battery might not allow it to re-set at next key-on but then neither would an ABS controller re-set)

 

So having to remove your seat & use that switch for an ABS re-set is either clearing a different ABS failure, OR just the fact of turning the engine off then removing the seat is allowing the low voltage failure to re-set at next key-on & the underseat switch + re-set wasn't actually required. (using it just forces you to turn the key off)

 

Next time you get an ABS failure that won't clear with just a simple key-off then key-on then you might take a bit of time & retrieve the failure code(s) just to see what is really going on with your ABS.

 

 

-(Reading ABS 2 controller stored fault codes)-

 

“Make sure battery voltage is at or above 12 volts, with key on”

 

1)- First- place analog voltmeter between pin #2 of ABS diagnostic connector & ground.. (don’t use a digital voltmeter as most won’t respond quick enough to show stored codes correctly)., Another way is to use an LED & resistor in place of the voltmeter.

2)- Then- turn ignition switch on.

3)- Voltmeter should indicate (close to) a steady 11volts, (IF) no fault codes are stored.

4)- If it has stored fault code(s) in the ABS controller it should show as voltage swings or drops. To find ABS code or codes just count the voltmeter needle swings towards zero volts.

 

If you have multiple stored codes it will show them in order with a short pause between each code then start over & go through them again.

 

-(Here are the ABS 2 fault codes)-

 

1)- front pressure modulator.

2)- rear pressure modulator.

3)- front sensor.

4)- rear sensor.

5)- battery voltage low.

6)- ABS relay.

7)- ABS control unit.

8)- sensor gap front or rear.

 

Note: not all ABS failures are trapped & stored as a failure code.

  • Like 1
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Valuable info, DR. Thanks. 12V circuit tester from Harbor Freight is less than $5, but has incandescent 3W bulb. Think that would work? *Link*

 

Background: helping a friend with R1100RT. His solution: black electrical tape over the blinking lights.

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Valuable info, DR. Thanks. 12V circuit tester from Harbor Freight is less than $5, but has incandescent 3W bulb. Think that would work? *Link*

 

Background: helping a friend with R1100RT. His solution: black electrical tape over the blinking lights.

 

Afternoon TheOtherLee

 

I don't know, a 3w bulb might draw too much current & not respond fast enough. I guess you could try it. (seems like it might work more as a ground connection than a reference indicator though)

 

I just use an old (re cheap) analog voltmeter that cost almost nothing. The needle swings are easy to see & it has always worked.

 

I have a friend that uses an LED that is resisted to operate at 12v (polarity is important when using an LED), also a 12v LED (without resistor) will work, but again polarity is important. (try the LED both directions & if no usable reading then try hooking the LED between 12v B+ & the underseat diagnostic connector (that has worked for some).

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  • 4 weeks later...

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