I have another question, but wanted to say thanks again for the help that the community has already provided in my short K100 life!

I bought an 1985 BMW K100 which was running, but had required hot wiring in order to run and a "permanent hot wire" was set up, I removed all the jury rigged wiring and reinstalled a newish right side hand controls and wired the bike per the online diagrams. However, when I turn the ignition on and depress the clutch, then press the start button - the fuel pump runs and you can hear fuel feeding - but absolutely nothing from the starter. Nothing turning over or anything. Battery is full and it RS prior to my supposed correct rearrangement of wiring. My question is, if the starter is not even making a peep - where should I start? Thanks in advance, I truly appreciate it!

It is normal for the fuel pump to run like that. Check you are getting 12volts at the starter when you press the start button and if you are then new starter brushes will be the order of the day, if no 12 volts then check at the starter relay to see if it operates.

Where is the positive test point for the starter, I'm only familiar with the negative? And what is the best way to check the starter relay? Thanks for the patience in working with me, I'm horrible with electronics!

you should get 12 volts at the starter connection, that is the nut where the black cable attaches.
To test the relay first there are 2 screw terminals if you short those the starter shouls turn the engine, if not then check for 12volts at the rear most terminal, should be a thick red wire direct from the battery. if there is no 12 v there then a jumper direct from positive of the battery to the starter terminal. if still no go the starter is no go and probably needs brushes, there are a few threads on here about that so a google search from the forum page will find them.
If the starter does work then the relay needs checking, push the button and listen for the click as it operates. if it does operate then the contacts are most likely the problem. open the relay by prising the cover off and you may be able to clean the contacts but a new relay is probably the best.
If the relar doesn't click then check that you get 12v on the black/yellow wire in the 2 pin plug, if you do get 12v then the relay is shagged, if not then you will need to check the start button, we shall go futher from there if needed
have fun and keep the fuel cap closed as there are no auto clubs on the planet that will do a recovery from the moon.

I hadn't used my my volttimeter for about a year until just now and I think it's broke, I replaced he battery and it won't register anything (new batteries) - so I tried to hot wire it direct from the battery to the starter and I'm getting sparks, but no turning over. Sounds like it could be the starter and needs the brushes but what I don't get would be why it worked with the hot wire prior to me replacing the right hand ignition switches and now (a couple days later) it wouldn't.

The kick stand is up but the center stand is down, that shouldn't affect it correct?

Will get a new volttimeter tomorrow and see where I am at with the rest of the recommendations, thanks!

So I am getting 12.5 from the battery, and the same from the two terminals on the starter relay posts. When I place the probes on the battery and the starter I don't get anything but I'm not sure if I am doing it correctly because I am not getting anything.

No. All you're doing there is measuring the voltage drop in the wire from the battery>relay contacts>starter terminal, which will be zero as there is little to no resistance. You need to attach the black probe to an earth or the Neg battery terminal and red probe to the starter terminal. That will tell you if you have power to the starter. Following Rick's instructions... if you have no power at the starter terminal there's likely a problem with the relay. If you do have power at the starter terminal, and the starter is not turning, you have a problem with the starter, likely to be the earthing or brushes. If the starter has not been out for a while there could be corrosion at the bed where it bolts down (2 bolts). This is the return earth for the starter and other components.

To complement Kaptain's advice, you should be probing the following terminals on the relay with the Red probe of your voltmeter.



While probing the starter terminal post indicated in the picture above, press the starter. The relay should engage and you should read +12V on your meter.

or ....

probe both those big terminals with the volt meter

there should be voltage across them until you press the starter

if no voltage ,,,suspect starter brushes or earth of the starter motor ,,,,if pressed to start and there is still higher than 3 volts voltage ...then the relay is stuffed .

I see, thanks for the support guys. Just got to work so it will have to wait until later in the day but I definitely appreciate it ... I really don't want to have to take this to the dealer for something I can work through with yall's help!

So I just tried the probes on the two main posts of the starter relay while pressing the ignition and there is NO drop in pressure (maintains 12.4ish) so judging off what you said the starter relay is likely the culprit correct? Thanks again y'all, I'm getting excited we may have figured it out!

If you can hear the starter relay "clicking" and have power on both posts:
Put the bike in 5th gear and push it forward/backward a couple of times.
Then put the bike on the center stand in neutral and try to start it.
If the bike doesn't start after that, do the following:
Disconnect the wire from the starter. take your ohmmeter and test the continuity between the starter connection (on the starter) and the ground on the battery.
Let us know what you find.

CF

did you here a click ? whilst pressing the start button ?

energyhutch wrote:So I just tried the probes on the two main posts of the starter relay while pressing the ignition and there is NO drop in pressure (maintains 12.4ish) so judging off what you said the starter relay is likely the culprit correct? Thanks again y'all, I'm getting excited we may have figured it out!

From your post I'm guessing you connected the black and red probe to either terminal?? Sorry Mate but that's not the test Robmack's directions assumed you would connect the black probe an earth connection first and then 'probe' the starter terminal with the red probe (the one at the top in the pic).

However it does confirm that your relay contacts are 'open' (that's good) because you have a 12V drop between the battery side and the starter side of the contact terminals. No voltage change when you press the starter button means your contacts aren't closing. This indicates something amiss in the control coil circuit (the other smaller contacts on the relay. Disconnect the relay for ease of access and there are 2 things you can test...
1. Apply 9-12V directly to the control coil terminals. You should hear the contacts click. If not the coil is most probably fried (unlikely). If you hear a click go to test 2.
2. Connect the black probe and the red probe to the control coil wires and test for 12V when you press the starter button. No voltage will mean problem with switch, connectors, fuse??

Cheers

No, unfortunately there is no clicking regardless of what I do.

I must be honest, in that I am getting confused when you say probe the "starter terminal" ... Are we talking the nut on the starter which has a black wire running to it from the starter relay? Or are you meaning something else ... And is there a specific ground I need to be using?

Also, I am not familiar with a "control coil circuit" ... Sorry guys I am sorry it's a drag trying to convey your message to a total moron with electrics, but regardless I appreciate your inputs!

First off, most voltage measurements on a vehicle are referenced to "ground".  Ground is normally the negative terminal of the battery and on most vehicles (including the K-bike) is directly connected with a wire to the chassis. That makes the frame of the vehicle the same potential as the negative terminal of the battery.  Normally, you attach the Black probe of the voltmeter to either the negative terminal of the battery or to a part of the frame with bare metal - it's the same thing.  

Yes, the starter terminal is the nut on the starter which has a black wire running to it from the starter relay.  The outside case of the starter is electrically connected to the frame through its mounting bolts and is therefore at "ground" potential.

The "control coil circuit" is all the components and wires and such that connects to the relay through a white plastic two-pronged connector.  You can see it in the photo I posted.  That circuit includes the clutch switch, the start switch, the transmission gear indicator switch, the instrument cluster, the keyed ignition switch, the fuses and the battery.  With the ignition turned on and the gearbox in neutral and/or the clutch pulled in, +12V will be presented to the start switch.  Pushing the start switch will present that +12V potential to the starter relay, causing the relay to engage and thus sending current from the battery to the starter motor and causing the motor to rotate.

There are several things that can get in the way of that successful outcome:
- the battery may be dead
- one or more fuses may be blown or defective
- the start switch could be corroded or broken
- the TGPI switch may not be working
- the circuit on the instrument cluster may not be working
- the clutch switch may not be working
- the start relay may be broken
- the starter motor may be in need of service (like a cleaning or changing brushes)

As you see, we're all trying to lead you through a diagnosis to identify the failing component.  Each hint that someone is giving is leading towards collecting evidence to point to the failure.

You need to have a strategy to the diagnosis and that strategy is to eliminate working components until you discover the one component that is failing.  
1. First, determine if the start motor is working.  This is very important because it is part of the ground circuit of the motorcycle and causes havoc if dirty.
2. if it is working, determine if the starter relay is working.  These relays are famous for failing but they usually fail closed, not open (as yours indicates)
3.  If it is working, then determine why it is not engaging when you press the start button.

@robmack and Kaptain Holister - thank you for taking the time to explain that, there is a lot I dont understant but that definitely clears up a bit. I went back out and tried to follow correctly what you intended - I placed the voltimeter negative on from ground and the positive on the starter terminal of the starter relay, when pressing the start button I had a reading of zero ... I cant help but feel that I am still doing things incorrectly.

When I press the start button the only click I hear is coming from the fuel injection relay - if there is a click from the starter relay its not loud enough to be heard over the click from the fuel injection relay.

Again, thanks guys for your help - wish I was able to reciprocate further.

Can the guage of wiring affect this process? When I attempted to correct the wiring from the previous owner I used some pretty thick wiring to run to ground from the battery etc?

+1 Robert. A good explanation and excellent strategy to follow.

Ok, so I opened the starter relay, the thin metal flap is currently held off of the opposing piece and both edges appear to be charred. I can manually depress the thin (appears to be) copper to touch the other side, however when I apply 12v from the battery direct to the terminals there is no movement of the thin metal tab ... I believe above is what called stuck in the open position (Kaptain Holister)?

This evidence is beginning to pointing to a failing start enable circuit actually.  The relay click is quite audible. Here is a recording of the sound that the starter relay makes.  So you should be able to hear it.

What this means is you have to find out what's causing the relay not to engage. Short answer: it's not getting +12V from the start switch output. So, next step is to see if there is +12V at the input to the start switch.

- Locate the right hand controls connector under the tank on the right side. It's a big white 9-pin connector covered by a plastic shroud
- Measure the voltage on pin 6 (Black with Green tracer) while simultaneously pulling in the clutch.

Answer: with the clutch pulled in, you should read +12V; with the clutch released, you should read 0V.

Report back what you observe.

energyhutch wrote:Ok, so I opened the starter relay, the thin metal flap is currently held off of the opposing piece and both edges appear to be charred. I can manually depress the thin (appears to be) copper to touch the other side, however when I apply 12v from the battery direct to the terminals there is no movement of the thin metal tab ... I believe above is what called stuck in the open position (Kaptain Holister)?

It's supposed to be "stuck in the open position" normally.

Try this since you have the relay removed and on the bench.

Take a 12v battery with two wire leads - one on +ve the other on -ve.  Touch the wires to the 1/4" wide metal tabs on the relay.  Does the relay make the noise as recored in my post above??

Definitely no start relay sound above under any circumstance. No clicking heard when battery cables applied directly and no action of the relay when cables applied directly.

When I disconnect the right hand controls, ground out the volitmeter negative lead, and place positive on spot six with the black with green tracer there is a 0.0 read out whole depressing the clutch. ...

Correction on the right hand controls, when I apply the positive lead from multimeter the reading is 10.26, when I engage the clutch the reading is 11.71 ...?

energyhutch wrote:Definitely no start relay sound above under any circumstance. No clicking heard when battery cables applied directly and no action of the relay when cables applied directly.

So, it appears that the starter relay is broken.  To verify the diagnosis, switch your multimeter to Ohms range, somewhere around 200 ohms full scale. Verify that the ohmmeter is working by touching both probes together; the reading should be zero ohms.   Then using the two probes, place one on one 1/4" tab, the other on the other tab.  I predict that you will not measure any resistance at all.  It will be infinite ohms, indicating an open coil.

Can you try and report back?

Just to make sure, you apply 12V to the smaller connections #85 and #86 (control coil)

I'd have to agree tho, its looking like the coil is fried.

Glad you mentioned that, I went back and rechecked, the relay is clicking when I apply the leads directly from the 12v battery ... Also, the ohms was measuring 19 when taken from the aforementioned (by both of y'all) 1/4 leads 85 and 86

Well, that's all normal.  Good to hear it's not the relay which is failing.

Based on Post #24 and #27, I'd say the start enable circuit and starter relay are functioning.  Now you need to confirm or eliminate the start switch as the problem (sounds like CSI).  With the relay still removed, take the voltmeter and measure the voltage on the white connector in the relay box that connects up to the starter relay.  Probe between the Black with Yellow tracer and ground.  Turn on the ignition, pull in the clutch AND press the start button.  You should get the same readings as you observed in Post #24.  That will prove the start switch is working.  If you read zero volts with this test, you need to service the start switch.

Ideally, you should remove the starter itself from the engine, recondition it and test it for proper function, I think.  There is a How-to on this site for performing that service.  Once you've finished this service, and before installing it back into the motorcycle, do the following:
1. clamp the mounting tabs of the motor securely in a vice.
2. take a motorcycle battery, some wire leads and secure the -ve of the battery to the case of the motor.
3. touch the +ve of the battery to the screw sticking up from the back of the motor. CAREFUL! DON"T SHORT TO THE CASE.  The motor should run.

If it does, you've now proven the motor is functioning.

Ok, sounds like a weekend adventure. I just can't thank y'all enough ...

Just to be fully clear on the history of I wasn't before ... The previous owner had a hot wired setup. If you had the ignition on, and shorted from the positive terminal of the battery to the screw sticking up on the starter, it would turn over and start .... I pulled all his make shift wiring and replaced the right hand controls and wiring.

I just don't get why the starter motor would have given out if I was able to use his shorting from the battery to the starter motor to get it running just a couple days ago.

Am I correct in that there is no positive lead going to the starter motor of any kind?

Thanks again, I am sure this is as frustrating for you guys as it is for me but I am learning a ton and grateful for this community!

It's very useful to learn how to read a schematic diagram so you can trace wires.  You'll be surprised that it's not really that difficult.  The difficult part is devising the strategy for diagnosing problems, understanding the expected results and deducing what's going wrong.

The starter motor is robust and should not have given out.  Bench testing as I described above will demonstrate that fact for you.

There is a +ve lead going to the starter:



The diagram above shows the starter relay. Pin 86 comes from the start switch. Pin 85 goes to ground. When you turn on the ignition, pull in the clutch and press the start switch, power flows in Pin 86 and out pin 85, turning on the relay.

Battery +ve is connected to pin 30, one of the main relay contacts, the ones which are burnt on your relay. The other main relay contact, pin 87, goes to one side of the rotor on the starter motor. The other side of the motor is grounded. When the relay engages (remember the description above), power from the battery flows through the main relay contacts, through the rotor windings to ground. The starter motor turns!

Yes I believe you are entirely correct, also unjust read your post on cleaning the starter motor - an excellent post. Does gauge of wire come into trouble shooting this type of problem? I know for a fact that I used some thicker wiring than was standard on the battery and grounding leads from the battery - just want to make sure that couldn't be part of the issue. Thanks again!

No, thicker wire will not be a problem.

What concerns me now is that you said you ripped out the PO's wiring mods. I'm wondering, have you restored the wiring harness back to the same state it was when it left the factory? In other words, did the PO clip OEM wires in the harness to make his mods and have you made appropriate repairs? We've seen pictures of some very creative wiring changes that were put in place because the original owner didn't understand fuel-injected motorcycle electronics.

I don't think the starter motor has "given out".
The fact that the starter motor has been recently working when hot-wired, and that a voltage drop was measured across the relay contact terminals (see post #12) meaning the starter motor is earthing, I think its highly probable its working ok. But would certainly be worth pulling the end off and checking the condition of the brushes.

@robmack - that was my biggest concern as well. Points where he entered any wiring was A) done in the right hand controls wire connector - which was replaced with an intact wiring connector with the right hand controls unit. And B) to the battery/starter relay. My focus has been on trying to ensure my understanding of the wiring diagram from the Clymers book is correct.

From the negative terminal of the battery I have one cable which runs to the frame ground below the fuel tank.

From the positive lead I have two wires, one goes to the starter relay I believe tab 30 (the rear most tab), and the other which joins a light blue wire en route to the alternator ....

That is the only wiring I have from the battery, and I believe the only wires which were altered by the PO. Does is sound that my connections from the battery are correct and not lacking?

energyhutch wrote:From the positive lead I have two wires, one goes to the starter relay I believe tab 30 (the rear most tab), and the other which joins a light blue wire en route to the alternator ....

That is the only wiring I have from the battery, and I believe the only wires which were altered by the PO. Does is sound that my connections from the battery are correct and not lacking?

That's not OEM. The Blue exciter wire from the alternator should go to Pin 9 on the OEM cluster. That setup you have could potentially blow the stator windings on the alternator.

As for schematics, download this one; it's easier to trace for a beginner since it is in colour.

Will ensure the blue wire correctly placed when I get home. Wow that is an excellent diagram - when I look at that diagram, from the positive battery terminal, I see three individual wires:
1- to the alternator
2- to the starter relay
3- to the fuel injection relay

However, on my bike, there is:
1- to the alternator
2- to the starter relay

***then there is a red from terminal 30 on the starter relay which goes to the fuel injection relay, but nothing direct from the battery to the fuel injection relay as depicted in the image. Is this important or does the current just flow through the relay terminal?

The exciter blue wire is properly on the 9 spot of the cluster.

So just an update. I replaced all the ignition wiring with new connections and grounds. I pulled the starter and bench tested it - which it passed - I cleaned it according to Robmacks well written tutorial, then re bench tested it to be sure all was still well and it was. Ensured fully charged battery and put her all back together, still no ignition - not even turning over. So I went ahead and reevaluated the starter relay which I am leaning on as being the faulty link in the ignition setup. I concluded this after reperforming the above reccommended evaluations (especially remeasuring the ohm fun). I have ordered a new one which should be here Thursday/forever.

I just wanted to say a big thanks again for everyone helping out and really working with someone who has a very small (but growing) education of these great bikes.

The starter relay being replaced did not solve the problem. I called the dealership and mentioned I would likely be bringing it in to get evaluated ... He said before I do that I should verify the hall sensors are working correctly, can anyone comment on the possibility of a ruined hall sensor or hall sensor wiring could produce a NO CRANK no start situation?

I think the most likely cause of your problem is a bad ignition switch.

duck wrote:I think the most likely cause of your problem is a bad ignition switch.

Easy way to prove it: find the plug'n'socket that connects the ignition switch to the rest of the loom, disconnect, then on the loom side jump red to green and slate (grey) to slate/blue.

energyhutch wrote:The starter relay being replaced did not solve the problem. I called the dealership and mentioned I would likely be bringing it in to get evaluated ... He said before I do that I should verify the hall sensors are working correctly, can anyone comment on the possibility of a ruined hall sensor or hall sensor wiring could produce a NO CRANK no start situation?

I thought that your previous findings proved that the starter relay was working OK and that the problem, as robmack suggested, was in the switches/wiring to the relay. This could be starter switch, connectors, ignition switch or corrosion on any number of connections.
imho I think you'll waste your money sending it to a dealer for assessment.  I doubt its the HES. There's some basic maintenance you could do that will most probably remedy the problem.

I fully agree, which - while tracing all my wiring connections I ran across messed up wiring associated with the HES - hence my questions regarding if there is a "possibility" of that could cause a no crank. If I could post a picture I would but aren't sure I'm able to do so yet ...

I totally agree with KH don't take it to a dealer. Most of the dealers know very little about the early K series because they see very little of any of the bikes after warranty expires.
Possibly a workshop that specializes in BMW as they have often been in the game for years and used to work on the early Ks.
One thing to consider is getting a complete good harness but if the switches have been messed with then that will only solve part of the problem.
One of the problems is that those of us who do understand this electricky stuff tend to use the buzz words and forget just how little novices know. I have tried to stay out of it because as we all know too many brothels spoil the cook or that might be too many cooks spoil the broth. We all have different ways of explaining things
Be patient there has not been a problem yet that has left here unsolved.

In answer to your question. Bad Hall Effect Sensors wont stop the engine cranking over but unless the ECU (Engine Control Unit) is getting pulses from the sensors then the injectors wont fire.
I would first try what Dai and Duck have suggested it is a very common problem.
From Post #7 So I am getting 12.5 from the battery, and the same from the two terminals on the starter relay posts. When I place the probes on the battery and the starter I don't get anything but I'm not sure if I am doing it correctly because I am not getting anything.

Was this when you pressed the start button or just doing nothing.
I am presuming here that the red probe was on the positive of the battery and the black probe on the starter terminal. Is that right?

Rick G, I appreciate the reply - as I do everyone above. I don't plan on taking her in just yet - I really want to work through this and everyone on here and other forums has been such a great help - if anyone is in or near Miami I'd be more than happy to pitch in a bottle of bourbon or whatever their fancy to help me get this figured out loll. It will come, thanks again for talks patience!

*** Dai and Duck, will attempt this in the AM and report my findings.