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Old Red One_Two
Joined: 04 Nov 2007 Posts: 7
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Posted: Mon Nov 05, 2007 6:41 am Post subject: Alternator Light won't go out!! 93 K1100RS |
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| Alternator light came on one Sunday morning after the bike had been ridden for 20 minutes and rested for one hour. During the twenty minute ride home the light went out. The bike was stopped, restarted after five minutes light came on then went out then came back on and stayed on. I removed the brush carrier from the back of the alternator and replaced with a secondhand but much healthier looking brush set. I attempted a restart but forgot that the battery was sick and cooked the starter relay and almost the battery and bike#**!!!. Gee it takes a while to get to the battery to disconnect it when you are in a hurry. NEW STARTER RELAY and overnight battery charge fired up and light went out and stayed out. Hooray, success. Two weeks later light came on on again and won't go out??!!* Any suggestions??[/b] |
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Euripides Brick Rider
Joined: 10 Aug 2007 Posts: 45 Location: Central Virginia, USA
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Posted: Tue Nov 06, 2007 10:44 am Post subject: Alternator problem |
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| Old Red: It sounds like your alternator slip rings and brushes are oxidized, dirty or worn. I suggest to remove the alternator and take it to a shop that specializes in rebuilding alternators and starters. Also, check all of your alternator terminals and all ground and all other electrical connections for corrosion. If you find oxidation or corrosion, spray the terminals with electrical contact cleaner and add dielectric silicone grease to the connections to help prevent oxidation of the contacts. If you need a shop that is good on rebuilding alternators or starters, I suggest to contact Automotive Manufacturers, 2400 N. Lombardy St, Richmond, VA 23220 (804-321-6861). They do good work at reasonable prices and have rebuilt the alternator and starter on my 1987 K100LT with good results. (I am in no way associated with them.) Also, check carefully all of your battery connections and especially the battery negative terminal main ground lead where it bolts to the transmission or engine case. This should be at least a number 8 wire size, Number 6 would be better. (On really dirty and oxidized connectors, I have had good success by spraying them with PB Blaster several times over several days and let them soak to disolve heavy corrosion.) - Euripides |
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Old Red One_Two
Joined: 04 Nov 2007 Posts: 7
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Posted: Tue Nov 06, 2007 10:56 pm Post subject: |
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Euripedes. Thanks for the suggestions. I did have one go at getting the alternator off but you guessed it the patent bolt in the inaccessible location (one of three) that holds the alternator onto the engine refuses to budge. I am trying to explore all the crazy options before having to disassemble the whole bike just to get the alternator off!!##**/.
I'm sure the electrical guys you mention are great but as I am in Australia I'll try someone local first. If I need to get it off. The fault probably is in the alternator as the bike has done nearly 180,000kms but I was thrown by the fact that just replacing the bushes initially seemed to solve the problem. Why two weeks later does it throw a tanty and suddenly not want to work. Does any of the circuit pass through the ignition key? Could that be at fault?
Old Red One_Two |
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Euripides Brick Rider
Joined: 10 Aug 2007 Posts: 45 Location: Central Virginia, USA
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Posted: Wed Nov 07, 2007 1:43 pm Post subject: |
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| Old Red: You are forgetting that the brushes you replaced in the alternator are only one-half of the problem. The brushes press and ride on the slip rings on the armiture. Both the brushs and slip rings wear when the armiture turns inside the alternator. The reason the light came back on is the wear and oxidation on the slip ring is causing the new brushes to lose electrical contact. I doubt the problem is in the ignition switch, unless the bike was left outside in the rain uncovered and water entered the switches. That will cause the contacts to oxidize and problems will result. Simply installing new brushes on a worn slip ring will quickly damage the new brushes. Also, if you have your alternator rebuilt, be sure to have new front and rear bearings pressed-in. However, with that many miles, I am not sure your slip rings can be machined or polished to like new condition and the armiture shaft is also likely worn and new bearings will not help. If that is the case, replace the alternator with a good rebuilt or new one. I also had a real problem removing my alternator because of a seized Allen type socket head cap screw. BMW uses three Allen head screws to mount the alternator. They really overtightened the screws! I had to resort to a small propane torch with a pensil tip to heat the screw and then used an Allen socket with a 18" leaver and it finally broke loose. There is also a plastic cover over the front of the alternator that must be removed to gain access to the mounting screws.- Euripides |
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Old Red One_Two
Joined: 04 Nov 2007 Posts: 7
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Posted: Wed Nov 07, 2007 5:00 pm Post subject: |
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Thanks. Yes I take all that on board and you are probably right. I guess the same guy that put your alternator on put mine on because the reason I am looking for an answer outside the obvious is that I don't really want to be bothered standing on my head for a day to get this blasted bolt out. My troubles did start on the day the bike did get a little too wet so that is why I wondered about the ignition switch.
Old Red One_Two. |
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Geoff Flying Brick Rider

Joined: 08 Feb 2007 Posts: 551 Location: Illinois
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Posted: Thu Nov 08, 2007 10:36 am Post subject: |
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This might be a stretch, but I'll throw it out... Someone at the factory likes to gorilla tighten plastic tie wraps. Over the years, this will destroy wiring insulation, leading to shorts and opens. I experienced this problem with an R1100 boxer. The motor would cut out when the steering was turned full lock. An over-tightened tie wrap severed a wire leading to the ignition switch. I have also read about this problem on many message boards.
Since your alternator light illuminates intermittently, there might be a damaged wire. Trace the wiring from the alternator and check the ones secured by tie wraps. _________________ 2000 R1100RT
2008 H-D Electra Glide Ultra Classic |
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Old Red One_Two
Joined: 04 Nov 2007 Posts: 7
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Posted: Thu Nov 08, 2007 3:55 pm Post subject: |
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Thanks old mate. This sounds crazy enough to fit the symptoms. Weekend coming up should be out riding but another day tinkering looks like. I am starting to get desperate. Even went looking at Honda Blackbirds the other day.
Old Red One_Two |
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Euripides Brick Rider
Joined: 10 Aug 2007 Posts: 45 Location: Central Virginia, USA
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Posted: Thu Nov 08, 2007 6:21 pm Post subject: |
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| Geoff: Thank you very much for the information about the overtightened cable tie straps! I was not aware of that as being a common problem. I have had problems with my '87K100LT cutting-off when the handle bars were turned to the stops. I thought a switch or connecctor was the culprit, never suspecting about cable ties breaking wires inside the harness! Good grief, what next? I would guess the only check for that would be to use an ohmmeter while flexing the wiring harness??? Thanks again! - Euripides. |
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Frank Flying Brick Rider

Joined: 30 Jan 2006 Posts: 170 Location: Gold Coast Australia
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Posted: Sat Nov 10, 2007 3:47 pm Post subject: |
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G'day Old Red
Where abouts in Oz are you?
Any good auto electrican should be able to rebuild the alternator for you.
Did my starter and alternator on my K100 and it cost only $100 to do (mates rates).
Also the suggestions about overtightened zip ties is a good place to check. never know.
Welcome and enjoy the rides. _________________ Ride safe
Frank
Gold Coast Australia
BMW 1997 K1100LT - White
Ulysses Member 33144
StruggleTown Tourers |
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Flying Duck PsyKotic Waterfowl

Joined: 27 Jan 2005 Posts: 10102 Location: Bumf***, WA
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Posted: Sat Nov 10, 2007 4:05 pm Post subject: |
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If your bike is a 93 then it has the old 32A alternator. Instead of putzing with that, now would be a good time to find a 50A alternator from a 94 or later bike. It should bolt right up and will give you lots of extra amps which is handy for adding running or driving lights.
(Note that you if you're getting one from a breaker then one from an R850, R1100, R1150 of mid-90s vintage would also fit as they used the same unit.) _________________ 93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
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Old Red One_Two
Joined: 04 Nov 2007 Posts: 7
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Posted: Sun Nov 11, 2007 12:09 am Post subject: |
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I'm in Brisvegas! I have just checked the voltage on the little wire coming from the ignition switch.
Key off: volts = Zero
Key on: volts = 00.7 volts
This seems to suggest high resistance or a short. Shouldn't it be 12 or so? Or am I missing something? Seems to me I need to lift the tank up and trace the wire back until I can get 12 volts.
Old Red One_Two |
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Tim (Midland Section) Flying Brick Rider

Joined: 08 Apr 2005 Posts: 960 Location: Pinxton, Nottingham, England.
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Posted: Sun Nov 11, 2007 7:25 pm Post subject: |
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My last K developed a similar fault. Due to a tight wire around the headstock to the ignition switch. Aparrently it is more common than one would expect.
Wires tend to snap inside the insulation, in my case 1" from the switch. _________________ Regards Tim,
Grey haired riders don't get that way by pure luck
1996 Guzzi Cali3 LAPD
1972 750 Commando
G6HRN
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Euripides Brick Rider
Joined: 10 Aug 2007 Posts: 45 Location: Central Virginia, USA
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Posted: Tue Nov 13, 2007 10:24 am Post subject: |
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| Tim: Thank you for that information as it will help me to diagnose my problems. Question: What year and model K bike was the previous one you refer? Mine is a 1987 K100LT. How many wire breaks did you discover? Were the breaks in the cables near the control head/ignition switch and contained in the respective switch wiring harness; or further back in the main wiring harness? Thank you very much. -Euripides |
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Geoff Flying Brick Rider

Joined: 08 Feb 2007 Posts: 551 Location: Illinois
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Posted: Tue Nov 13, 2007 11:05 am Post subject: |
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Euripides, I would begin by checking wires near the steering head. Wires pivot in this area during steering, and tie wraps are used to secure wires to the frame. Check the wires near the ignition switch, too. _________________ 2000 R1100RT
2008 H-D Electra Glide Ultra Classic |
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Tim (Midland Section) Flying Brick Rider

Joined: 08 Apr 2005 Posts: 960 Location: Pinxton, Nottingham, England.
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Posted: Thu Nov 15, 2007 8:41 pm Post subject: |
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| Quote: | | Question: What year and model K bike was the previous one you refer? |
It was a K1100LTSE, I expected yours 2 B a k11. However they are so similar. I concur with Geoff, that checking around the headstock is where one finds a common fracture area. _________________ Regards Tim,
Grey haired riders don't get that way by pure luck
1996 Guzzi Cali3 LAPD
1972 750 Commando
G6HRN
#485 |
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Old Red One_Two
Joined: 04 Nov 2007 Posts: 7
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Posted: Sat Nov 17, 2007 4:23 am Post subject: |
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Well I am creeping up on the problem. Traced the blue wire back from the alternator and found 12volts when key was on back where it comes out of the instrument panel. Cut the wire spliced in a replacement and got 12volts to the alternator. Fired up okay and presto alternator light went out. Went for a short ride and eventually the abs light went out but couldn't get the general warning light to go out. ??**##!! Thought it was too simple.
Old Red One_Two |
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Tim (Midland Section) Flying Brick Rider

Joined: 08 Apr 2005 Posts: 960 Location: Pinxton, Nottingham, England.
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Posted: Sat Nov 17, 2007 5:04 pm Post subject: |
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general warning light is satisfied when both brakes have been operated once & the rear lamps have continuity. _________________ Regards Tim,
Grey haired riders don't get that way by pure luck
1996 Guzzi Cali3 LAPD
1972 750 Commando
G6HRN
#485 |
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Old Red One_Two
Joined: 04 Nov 2007 Posts: 7
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Posted: Sat Nov 17, 2007 6:09 pm Post subject: |
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Yes thanks for that. I actually read myself to sleep last night with the Clymer Manual/ Wiring Diagrams!! Came to the same conclusion so am thinking of checking both brake lamps and whether each brake switch operates.
OLd Red One_Two |
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