ABS Fault

[JimmR75]

My recently new to me (month or so, < 1K miles seat time) 97 RT with 79K miles on it has developed an ABS fault under conditions peculiar to me.  I commute 60 miles round trip to work and it has recently gone into ABS fault (alternating flashing ABS lights on the instrument panel) at 12 ~ 15 miles into the commute.  Coincidentally (or not), lower temperatures seem to make it more likely to do this.  

 

If I pull over, shut down and restart, I can continue the ride without any further issues.  The ABS behaves otherwise with the ABS lights on with the key and go out as I pull away.  

 

I have also owned a 95 RSL that has a temperature related ABS issue.  On cold mornings (<35F) the ABS lights will not extinguish when I first pull away.  If I stop, shut down, and restart they will behave normally for the remainder of the ride.

 

So, I have two questions in my mind:

 

1. What can trigger an ABS fault on the RT this consistently (12~15 miles into the ride with possible temperature correlation)?

2. What can keep the ABS on the RSL from setting properly on a cold morning only to set properly so quickly after a restart?

[RK Ryder]

In my case, it has been a weak battery that caused the ABS fault.  

[Michaelr11]

It's important to take note of when an ABS fault occurs.  Most ABS faults won't clear with a key OFF and those require a reset.  I think that the only fault that clears with a key-off-on is the low voltage fault.  Cold temperatures typically make your battery voltage drop and it works harder to start the bike.  The fault 12-15 miles into the ride is odd.  When does it happen?  While riding, pulling away from a red light or stop, after turning off the motor?  How old is the battery?

[JimmR75]

The fault occurs while riding, not stopping or pulling away.  The distance / time of the occurrence is nearly identical each time.

 

Battery is nearly new and is on tender while parked.

 

I run a voltmeter in the powerlet outlet on the fairing and it indicates 13+ volts while running including during these events. 

[Jim Moore]

My Y2K R1100RS has done the same thing to me a few times. On the way to work on a cool morning, within 500 yards of the same spot each time (2-3 times). It always resets so I've never troubleshot further.

[dirtrider]

2 hours ago, JimmR75 said:

My recently new to me (month or so, < 1K miles seat time) 97 RT with 79K miles on it has developed an ABS fault under conditions peculiar to me.  I commute 60 miles round trip to work and it has recently gone into ABS fault (alternating flashing ABS lights on the instrument panel) at 12 ~ 15 miles into the commute.  Coincidentally (or not), lower temperatures seem to make it more likely to do this.  

 

If I pull over, shut down and restart, I can continue the ride without any further issues.  The ABS behaves otherwise with the ABS lights on with the key and go out as I pull away.  

 

I have also owned a 95 RSL that has a temperature related ABS issue.  On cold mornings (<35F) the ABS lights will not extinguish when I first pull away.  If I stop, shut down, and restart they will behave normally for the remainder of the ride.

 

So, I have two questions in my mind:

 

1. What can trigger an ABS fault on the RT this consistently (12~15 miles into the ride with possible temperature correlation)?

2. What can keep the ABS on the RSL from setting properly on a cold morning only to set properly so quickly after a restart?

 

Afternoon  JimmR75

 

Could be one or more of many things, a wheel speed sensor air-gap being real close to max specs is one, or an intermittent wheel speed sensor is another. 

 

Whatever it is it is a self-resetting fault as it goes away at next cold-start ride-away (so that limits the possible faults)

 

If the problem occurs while just riding along not using the brakes, or not using a lot of battery voltage, then that usually (but not always)  points to wheel speed sensors. 

 

If the problem occurs while riding but right after riding off from a stop then it is usually (but not always) the ABS system finding something amiss during a piston position check (that rrrruuuupppp that you hear right after a ride-away)  

 

 

My suggestion is to get  a voltmeter (old analog needle type) then grab the stored ABS failure codes.

 

If you don't know how to do this then post back & we can write up the procedure. 

[JimmR75]

DR, thanks very much.  Let me check the gaps first and I'll respond here.

 

As always, this forum an amazing resource.

[dirtrider]

1 minute ago, JimmR75 said:

DR, thanks very much.  Let me check the gaps first and I'll respond here.

 

As always, this forum an amazing resource.

 

Afternoon  JimmR75

 

When checking the gaps try to move the wheel sideways as a loose bearing (wheel bearing or crown bearing)  can cause the gaps to get wide when the wheel deflects. 

[Paul De]

My '99RT presented similar intermittent symptoms to yours. I verified the air gaps were in spec and battery tested good. It finally went full fault and turned out to be a bad front wheel sensor. The fact that it doesn't fault on startup and the possibility of temperature relationship would point suspicion to a wheel sensor going bad. For me the good news was that bike at the time was still under warranty as the OEM sensors are pricey.

[JimmR75]

Thanks Paul, is there any way to test the wheel sensors?

 

My manuals have the procedures for installation, removal and adjustment, but I don't see any testing or specifications.

 

Thanks in advance for any assistance.

[Paul De]

Hi JimmR75,

 

I don't see anything in my documentation that show testing of the pulse sensor.  My guess is that the pulse sensor would have some nominal resistance.  Also, it could test fine until you either catch it in the intermittent failure mode or when the pulse sensor goes full time failure. I suspect if the pulse sensor is bad, the resistance would go to infinity (open circuit), or maybe almost zero resistance (short).   What I am uncertain of is what is the nominal resistance value?

[The Fabricator]

I don't have any specs either.  You can measure the resistance of one against the other.  If both are the same or close, then they are ok. 

Measure voltage output with a peak reading voltmeter.  A common voltmeter with an adapter for reading peak voltages will do.  Again, compare front sensor voltage with rear.  Probably on the order of 5v.  

If the failure is intermittent, it would have to be in a failed state to be a low or no voltage reading.  To generate a voltage, spin the wheel.  Try heating up with a heat gun while testing.  Probably 100 to 150 degree area would be enough.    A  broken internal with will sometimes open circuit with increase in temperature.

[dirtrider]

2 hours ago, JimmR75 said:

Thanks Paul, is there any way to test the wheel sensors?

 

My manuals have the procedures for installation, removal and adjustment, but I don't see any testing or specifications.

 

Thanks in advance for any assistance.

 

Afternoon JimmR75

 

At room temperature (temperature effects resistance)  both front & rear sensor resistance  should be in the 130 ohm to 150 ohm area, but that is just a nominal not an absolute. Seeing as they only act up after riding for a ways then you probably won't find a smoking  gun  when testing the sensors  statically. The front & rear resistance  can also vary a little from each other  & still be fine as long as they are within, or close to, the room temperature resistance window.  If you compare front to rear don't assume one or the other is bad just because they don't test the same.

 

 You can also do a wheel spin test-- a good wheel speed sensor will generally produce an alternating current (AC) voltage reading of 50 to 700 MV when the wheel is spun at a speed of about one revolution per second. Because it is a pulsed signal you need to be on the voltmeter's A/C setting (DC won't work correctly).

 

By far your best way to test the speed sensors "at time of failure"  is to let your ABS system do the testing for you-- So just use an analog  voltmeter  (old meter with a swinging needle). Then see  what failure code or codes the ABS system has trapped while riding. If you have an intermittent wheel speed sensor then your code read out should show a failed front or rear sensor. 

 

_  front sensor = code 3

_  rear sensor = code 4

_ excess sensor gap (either front or rear) = code 8

 

I probably won't be back to this thread until I find another place with a WiFi signal (who knows when). 

[JimmR75]

DR, sorry if I sound ignorant, but where do I test for the retained codes in the ABS system?  I am familiar with the plug near the air filter that is shorted to clear a persistent fault, but have no experience beyond that with the ABS system.

 

Thanks in advance.  

 

- Jim 

[dirtrider]

44 minutes ago, JimmR75 said:

DR, sorry if I sound ignorant, but where do I test for the retained codes in the ABS system?  I am familiar with the plug near the air filter that is shorted to clear a persistent fault, but have no experience beyond that with the ABS system.

 

Thanks in advance.  

 

- Jim 

 

Morning Jim

 

I am very far away from my shop computer so sent you a PM with the info (check your messages on this site).

 

I can only check this site & reply to PM's when I can get a WiFi signal so I'm not ignoring you if I don't answer your questions quickly.   

[Michaelr11]

2 hours ago, JimmR75 said:

DR, sorry if I sound ignorant, but where do I test for the retained codes in the ABS system?  I am familiar with the plug near the air filter that is shorted to clear a persistent fault, but have no experience beyond that with the ABS system.

 

Thanks in advance.  

 

- Jim 

  http://www.largiader.com/abs/absfault.html

 

Jim, go to this page on Anton’s site. He explains the fault codes and has a link in the article to a code reader. The article covers the ABS2 and earlier systems. I don’t think it covers I-ABS.