Electrical, lights problem, K75RT 1994

[flingride]

Hi everyone, need help with this one.  K75RT 1994, 35800km

While riding, head lamp and rear light went off. When trying to use flasher, both left and right flashers go on at the same time if I presss either left or right flasher switch. If I stick on the switch, they blink together as if hazard were on. Same thing with the switch to turn flasher off. Horn does not work. When putting hazard, they work fine, when stopping them, right flasher goes on by itself.  No lights in speedomeeter or rpm un dashboard. These problems seemed to had happened at the same time. 

Any idea? all fuses are ok.

Thank you!

[johnny]

greetings flingride...

welcome to motobrick.com...

first thing i would do is this...

http://www.motobrick.com/index.php?topic=5678.0

j o

[K75RT Keith]

Had the same issue.  If you want the problem to cease do the following:  Clean the starter (instructions in the Liberry) and clean all the grounding points.

If you want a more convoluted fix, or want a reason to tear your ride apart, I'm sure someone on here can help you find it

[flingride]

greetings flingride...

welcome to motobrick.com...

first thing i would do is this...

http://www.motobrick.com/index.php?topic=5678.0

j o
[Thanks Johnny.  It is my first BMW K75RT.  I'v tried your advice and problems are remaining.  I will work on Keith's recommandations tonight and will get back with results]

[Inge K.]

Could be a idea to have a set of new carbon brushes for the starter at hand, too.
The positive brush normally wears out much faster than the negative.

[K75RT Keith]

+1 on Inge's suggestion.  Get the brushes. 

[Inge K.]

And, before dismantling....mark up the rear end cap relative to the stator.

[flingride]

Could be a idea to have a set of new carbon brushes for the starter at hand, too.
The positive brush normally wears out much faster than the negative.
[Is it easy to get them and where could I buy them? thx!]

[K75RT Keith]

Yes, it is easy to get the brushes.  Dealer will either have them in stock or can order them for you.  Other options might be aftermarket suppliers such as Motobins, Beemerboneyard, Moto-eletriks, 

[flingride]

Yes, it is easy to get the brushes.  Dealer will either have them in stock or can order them for you.  Other options might be aftermarket suppliers such as Motobins, Beemerboneyard, Moto-eletriks,
[Thanks for the info.  I did not do the work yet and I intend to do a test first by unplugging the starter and test de problems while only being on the battery without the motor running and after another test with the starter still unplugged and the motor running.  I believe that if the starter is unplugged, I should not get problems originating by the starter electrical problems and that if the problems are coming from the starter, then all the things (flashers, horn, head and tail lights) should be working properly.

Any toughts?]

[K75RT Keith]

Had the same issue. If you want the problem to cease do the following:  Clean the starter (instructions in the Liberry) and clean all the grounding points.

If you want a more convoluted fix, or want a reason to tear your ride apart, I'm sure someone on here can help you find it

I'm not sure what you want to hear.  It is a 25 year old machine and pretty much every problem that you may have has happened before and has been documented here and at most every site that discusses the K-bike.   If you want to take the long and expensive route, Replace the wiring harness, all the switches, relays, fuses and lamps.  Buy a new battery and reverse the k-newter valve.  End result will be you spend  a lot of money with no real improvement. Or If it were me (and it was) I wouldn't waste the time because it is a 99.9% chance the starter is the issue and the brushes are worn out either by use or age and the carbon build up is the culprit.   

[Motorhobo]

+1 what Keith said. If you're going to unplug it, might as well just remove the 2 bolts that hold it in place and pull it out. Once it's out, it's 2 screws to take the bousing off and look at the brushes. Don't forget what Inge said about marking the cap and housing. If you put the housing on backwards, the starter will turn in reverse and of course the bike won't start. Don't ask me how I know that.

[jamato]

Hey There,  I just went through this.  It was my starter motor.  The Starter Motor is the ground for the electrical system.  These are easily rebuilt or you can find a good one online for around $90. 

As soon as the starter motor was replaced all was good. 

Hope this helps

1987 K75s.

[Inge K.]

I intend to do a test first by unplugging the starter and test de problems while only being on the battery without the motor running and after another test with the starter still unplugged and the motor running.  I believe that if the starter is unplugged, I should not get problems originating by the starter electrical problems and that if the problems are coming from the starter, then all the things (flashers, horn, head and tail lights) should be working properly.

To verify that the starter is the problem (and if everyone replying to this thread just tell you jokes or not)........

Use a jumper cable or similar and ground the starter input terminal, turn on the ignition.
Do not touch the starter button, your flashers, horn and light should now function as normal.

[kioolt]

Hey There,  I just went through this.  It was my starter motor.  The Starter Motor is the ground for the electrical system.  These are easily rebuilt or you can find a good one online for around $90. 

That's not quite true about the starter being the ground for the ELECTRICAL SYSTEM.  The starter motor provides a ground path for the Load Shed Relay coil.  The LSR when not energizing will cause the lights and other non-essential for engine operation devices to not work.  This was done by the engineers to decrease the load on the battery when using the starter motor.

All of the essential devices on the motor, e.g. ignition module, fuel injection module, etc do not get their ground through the starter motor.  They get their ground through the chassis.  Even the lights that don't work when you have a starter motor problem actually get their ground through the chassis.  It's the LSR that has them turned off when there is a starter problem.  But it is the hot side of the lights that are turned off not the ground.

[K75RT Keith]

One other thought.  Clean All the grounds.  Battery cable and under the tank.  Use a Sotchbrite pad or sandpaper to clean the surfaces and when reassembled, cover with dielectric grease to keep out moisture.

[skidmore]

Your problem is identical to the one I was having but I had starting problems as well. I removed and cracked open my starter, cleaned the commutator with a brass bristle brush, installed new brushes (thought they weren't needed - my bike is mid 70,000 miles) and solved the problem. You may be surprised how bright your headlight is afterward. Mine used to burn yellow. After the cleaning, it burned a blazing white!

I scoured the web for how-tos and technical info on both diagnosis and repair. Our very own Motobrick lieberry is a good source. Another one I found beneficial is this one: http://www.k100-forum.com/t2342-starter-motor-cleaning-tutorial. As advised here and elsewhere, MARK YOUR END CAPS with permanent marker of some sort or a scratch awl etc.

Here is a before and after of my starter. Note the pile of carbon dust in the before pic; 75,000 miles and 22 years of duty!

[flingride]

Here what I did this morning,

I disconnected the starter and jump the wire to the negative poll.  I disconnected also the right big connector (white with 9 pins) under the gas tank. here is what I tried then:

-hazard flashers are working
-left flasher is working
-pressing the horn, I can hear the relay but no horn, I cannot hear the relay when the big white right connector is connected
-obviously, right flasher is not working  as the switch for turning off the left flasher
-front head light is not working
-tail light is not working
-tail light and small front white light are working as parking lights
-break light is not working , but is working when big white connector is connected

I Now suspect that there could be a short between the right white connector and one of the electrical features

[Scott_]

The circuit(ie fuse #1) for the running tail light and the brake light(via the bmu module) does go thru the right side kill switch, so if you have the multi-pin connector disconnected they won't work.
The headlight circuit also goes thru the right side wire harness as well. Euro market bikes have an on/off switch on the right side combo assy.
If you have a US market bike there is most likely a small jumper wire(on the male side) at the multi-pin plug as the basic frame wiring is the same for both markets. It jumpers pins 3(power in from load shed relay) to pin 7(out) and to pin 4(out to high/low switch on left combo switch)

The horn relay gets power from fuse #7, and the fuse power comes from the load shed relay. The horn relay coil is powered with +12 and the button on the left switch applies the ground to complete the circuit to activate the relay.

As far as the headlight, have you checked the socket at the back of the headlamp? I have had both sockets go bad on my bikes before I installed my EB relay kits.

[flingride]

Any chance the problem could originate from the Load Shed Relay?

I don't know which relay is the LSR and don't know how to test it,

Help for this one?

Thank you!

Picture of the control box:

[K75RT Keith]

OK, you opened the relay box and tested some circuits.  Have you cleaned the 3 grounding points (2 under the tank and the negative lead to the transmission/engine assembly) yet? What about pulling the starter and checking that?   

 

I have a couple extra relays  horn and LSR.  PM me if you need either or both

[flingride]

Hi,

Grounds are working, they were tested.
Removed starter and cleaned it.  Brush are in very good condition - see picture.
Reinstalled starter and the problems are remaining.

I inspected wires, did not see uncovered wires.


Any thoughts anybody?

thank you!

[flingride]

I just removed the 5 relays on the front side of the control box or top on the picture and I still get the problems.

I need a pill :dunno2:

... and help.

Thank you!

[flingride]

I found the problem   :clap: :clap: :clap:

I started to interchange the 3 relays that are similar on the top of the control box from the 5 on top.  The part number is identical for the 3 of them and is 61311459677.  So if I count them from 1 to 3 starting on top left (don't forget, there are only 3 balck identical relays, not the blue ones- look at the picture) going to right, it is the #3, i.e., the one on second row at right that is defect as I switched it with #1.

So I am asking for help to identify to which electrical components those 5 relays are associated. I understand that the one in defect has something to do with head and back lights, flashers and horn.  But what about the others.

Thank you all for your help!!!

[Inge K.]

Congrats! From the start it have been your load shedding relay that have been the suspected one.
But then the ground connection for the coil via the starter, which is the most common problem with the LSR.

In this case it's the LSR itself which is the reason to the problem.....change it with #2 which is for the horn
untill you get a new one.....#1 is for the fuel pump and other FI related, so you need it to be able to start.

Other relays: left middle, bulb monitor...left rear, flasher...right middle, fan+temp warning...right rear, starter.