96 R1100RS electrical gremlins

Afternoon,

I am trying to help a friend of mine diagnose a strange electrical issue on his bike.

Symptoms are:
Alternator light flickers while idling or decelerating.
While this is happening the tachometer will also flutter or just drop to zero.

as soon as the engine RPM's increase the alternator light goes out and the tach works just fine.

Battery connections are clean and tight.

Bike starts and runs smoothly but I have not ruled out a weak cell in the battery. Didn't have a volt meter to check voltage either. It was at home in my garage..

Not sure if this is related but the top ABS light also stays on full time and the brake light does not work.

tail light and turn signals all work fine.

Any suggestions on what to test next?

TIA

Roy

How old is the battery?

When was the alternator belt last changed? Have you examined the belt?

Put a voltmeter on the battery and record the voltage when the alternator lamp flickers at idle, and also when the lamp goes off above idle.

Absolutely check the belt, but tach flutter is a symptom of a failing ignition trigger (the Hall pickup assembly). Typically it's the wiring inside the local harness that falls apart; the factory allowed poor insulation on these wires from their supplier. GSAddict can save you dollars here.

A low battery/alternator output (possibly caused by a loose or worn belt) will inhibit the ABS from working properly; they require a pretty full charge. Old brake lines will also fall apart internally (often with NO external symptoms until it's too late!), not just degrading the brakes but actually clogging the little holes, including those inside the ABS module. Flush that fluid thoroughly. And if he still has the factory brake hoses, junk 'em and get a set of Spieglers.

Also, scrutinize very closely the action of your tail & brake lights - one may be dead while the other works, and the computer will sense this and light up one of the indicators on the dash. Typically, if the GEN light is On and the ABS light is Off, that's a "rear light" fault indication; but if the GEN light is Off and the ABS light is On, that means you only "residual" (not assisted) braking, which can be pretty scary if you need to make a quick stop.

Pauls1150 said:

...but if the GEN light is Off and the ABS light is On, that means you only "residual" (not assisted) braking, which can be pretty scary if you need to make a quick stop.

Click to expand...

Just ignore that little bit since it is an 1100, not an 1150 so you don't have whizzy servo assist brakes to deal with.

Start with voltage and verifying good grounds with little resistance between B- and points on the frame and engine. I just had a bizarre mix of symptoms which came back to an intermittent failure of a fuse. I'm not sure if any of the fuses could cause the issue you are having, but it is quick and easy to go through them. My issue was an original fuse with the exposed wire cracked at one end such that it intermittently lost contact and regained it. Visually, the fuse appeared fine. I just stumbled on the cause by wiggling the fuses noticing that I could cause the issue to come and go. As soon as I pulled on the wore with a pick, I could see the break. Start with the basics and easy stuff. Also go back to when the failure occurred and review the details. Did all the symptoms come on at once? Did anything else happen at the same time? (pothole, strange noise, just added and accessory...)

Good catch, no whizzies on the 1100 series... Might you have the ABS codes for those?

thanks Guys,
When it warms back up and drys out a little we are going to start trouble shooting again. Mid 30's and rain make working in an unheated area miserable.

Alternator belt and hall sensor were replaced last year. Approximately 5,000 miles on these items.


Will let you know if and we get this resolved.

Roy

Issue resolved

Morning all,
Checked the battery and connections and everything was clean and tight with good voltage readings so decided to pull and reseat all the fuses. Not sure which fuse or fuses were corroded but now everything works as it should.

Now if would just warm up a little we could go for a ride.

Roy

Pauls1150 said:

Good catch, no whizzies on the 1100 series... Might you have the ABS codes for those?

Click to expand...

No, but Anton does

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

roy said:

Morning all,
Checked the battery and connections and everything was clean and tight with good voltage readings so decided to pull and reseat all the fuses. Not sure which fuse or fuses were corroded but now everything works as it should.

Now if would just warm up a little we could go for a ride.

Roy

Click to expand...

If it stays good, thank dieselyoda. He is like a broken record that keeps repeating, "grounds and fuses - go back and check them again." If it fails, go back and check them again. You could find an intermittent fuse like I had.