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1999 R1100RT alternator


rxcrider

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This is a copy and paste from an ibmwr tech list email that I sent out this morning and I'll be posting on the MOA forums as well. Apologies if you are seeing it for a second or third time.

 

I've spent a few hours this spring resurrecting a basket case R1100RT for a local club member. This includes a new clutch , a better condition used wiring harness, rewired HES. Spiegler lines... I thought I had everything buttoned up and took it for an incident free 10 mile run on Friday night. I gave it a once over and topped off the oil on Saturday morning, then took it out again. I had a nice 20 mile ride on back roads and got it well into the revs and highway speeds with no issues. As I pulled back into my driveway, I heard an unusual buzzing / clicking noise and then the charging light popped on. When I revved the engine a bit, the light dimmed but never went out. The nearly new belt was tensioned properly and still in place. The wires to the alternator were still securely in place and showed no signs of damage. I have not checked voltage with the bike running yet, nor have I checked for a draw through the starter solenoid. My guess is that something in the alternator randomly took a dump (possibly the brushes or regulator) and I've ordered a Enduralast alternator preemptively since The bike needs to be running on Thursday for a trip on Friday. If you've dealt with this or have any other suggestions for things to look at, please let me know. Next up, voltage check and ohms through the starter solenoid cable lug to ground (hopefully open). After that it will probably be the fun of removing the alternator from the front because there are crank seal and front cover leaks to deal with as well. Thanks for any input - Jonathan

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Afternoon Jonathan

 

It does sort if sound like the alternator is giving issues.

 

If the large red wire going to the back of the alternator is tight & has good continuity to the battery B+ post then your problem is probably either inside the alternator or the ABS power relay is stuck & causing the ABS motor to continually draw lots of power.

 

ABS power relay is under a slide up cover on the side of the ABS unit.

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Thanks - If it were the ABS relay, would I hear / feel it while braking like the ABS was constantly kicking in?

 

If not, is it safe to start the bike with the leads under the slide up cover disconnected and insulated or is there a better way to diagnose this?

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Afternoon Jonathan

 

If it were the ABS relay, would I hear / feel it while braking like the ABS was constantly kicking in?-- Maybe yes maybe no. If motor is staying powered but the clutches are not engaged then you might not feel anything.

If not, is it safe to start the bike with the leads under the slide up cover disconnected and insulated or is there a better way to diagnose this? -- Yes, you can disconnect it there or at the rear of the alternator (ABS gets it's motor power from rear of alternator)

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On both harnesses, the wires at the alternator are crimped together in a single ring terminal. I'll opt for playing with the small hardware on the ABS unit rather than cutting wires. Thanks for the assistance.

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Afternoon Jonathan

 

If you can't hear the ABS motor running with the bike sitting still then try starting the engine & see if your charge light goes out.

 

 

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Key on and off with the tank removed, the bike was pretty much dead quiet. If the ABS relay / motor failure should have been easily audible at that point, it wasn't. I'll throw the tank on when I get home and verify that I still have the charging idiot light on after startup. I'll also loosen the belt and spin tha alternator by hand to see if I feel anything wrong in a mechanical sense. I'll also check voltage at rest and running.

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Alternator turns freely

 

Voltage at rest 12.6

Key on 12.3

Cranking. 9.5 - 11.5

Idle. 12.0

4000 RPM. 12.3

 

As checked at battery & solenoid lug

 

Only noises I hear when I turn the key on and off are the fuel pump and ABS flasher relay as they should be.

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Afternoon Jonathan

 

If the voltage measurement is the same at the rear lug of the alternator then you definitely have alternator issues.

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Michaelr11

Those numbers indicate your alternator is NOT charging. Your idle and 4k rpm voltage numbers are just the battery running the bike. You should see about 13.6-13.8 volts from the alternator.

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Rest & key on #s match, need to add a test lead to check creaking and running voltage, but only seeing 0.2 ohms from the alternator to the battery on both positive lead and ground.

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Afternoon Jonathan

 

That isn't very much resistance so you are probably good but it wouldn't hurt to check the running voltage at rear of alternator just to be sure.

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I've had the battery on the tender while I worked so all my numbers jumped Slightly 0.1 - 0.3 V, but that is it; essentially the same. Thank you for the reassurance that I wasn't overlooking something stupid that will bite me in the butt come Wednesday.

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I pulled the front cover off the motor to reseal and change the front crank seal which allowed the alternator to come out. I checked it against a 1996 spare from my parts bike and everything came out pretty similar with the ohm meter. I then ran it to AutoZone and had them test it as a 1979 320i alternator. (I Originally opted for 1974 2002 but they didn't have settings for that) The one I removed from the RT failed, but their printout wouldn't say exactly what failed. The spare passed so I'm running with the theory that the issue is strictly in the alternator. I installed an Enduralast alternator from Euromotoelectrics last night along with their upgraded regulator to boost voltage up toward 14.5 for better charging of the AGM battery.

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Fresh alternator w/ upgraded regulator and she is a quite happy 14.6V this morning... at least for the 18 mile ride to work.

 

Thanks for the input.

 

IMG_6442.JPG

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