Post by: Zfoster8 on November 02, 2019, 06:55:15 PM
I mentioned a bit in my intro post but figured i would dig into more detail about my problems with not being able to use my starter on my 87 K75S.
Picked the bike up about two weeks ago "not running". Previous owner said he thinks it was the starter relay, so thats where i started looking. Bike starts and runs very well with rolling bump start.
Basically, when i press my ignition button i can hear the fuel pumps running and nothing else. Starter does not engage, lights do not turn off, nothing else happens.
Things i have done and checked so far:
Replaced starter relay (more details in a bit)
Verified starter motor works (hot wire from positive battery terminal to starter, motor spins over and starts the bike)
Checked load cell (swapped with horn, both work fine)
Ripped apart handlebar controls, cleaned connections and checked working order, reassembled
Battery is good, healthy, and fully charged.
Starter relay: the one in the bike is beat, someone obviously already tried to tinker with it. The case was a bit busted. Replaced it with a new OEM bosch unit. After installing, realized previous owner had swapped the power and starter wires. Changed them to the right terminals, gave it a couple good whacks for good measure, no change.
For kicks i took apart the old one, and the terminals were not fused together, it actually looked pretty good inside.
I guess my next steps are to start checking everything else, but does anyone have any recommendations on where to start?
A quick note, the previous owner (or whomever) has done a lot of "custom wiring" to accommodate LED lighting i am guessing, and the wiring harness is pretty raggedy and hard to trace. This obviously makes it a bit more difficult.
Thanks in advance!
Post by: johnny on November 02, 2019, 07:26:42 PM
if you are serious... you better start poasting up photos here so we can see what you see...
and in this thread list everything that you think was done to the moto before you gotts it... and list everything that has been done after you gotts it... in chronological order of course...
be specific... no willy nilly... cause we dont deal in hearsay opinion mind reading hypotheticals here at motobrick.com... this is a fact based community based in reality...
j o
Post by: daveson on November 02, 2019, 07:35:58 PM
Post by: Zfoster8 on November 02, 2019, 07:47:48 PM
Johnny - Pictures incoming.
I have been able to trace almost all of the wiring and it does look like nearly all of the modified wiring is for lights and some accessories that were never finished being installed - There is an oil pressure gauge, voltage gauge, two toggle switches and a couple little notification lights. None of them work except the one indicating whether the turn signal is on.
I have done almost nothing to this bike so far aside from clean it up a bit and put in the new relay.
Added a "nude" of the old starter relay for your viewing pleasure
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Post by: johnny on November 02, 2019, 07:59:51 PM
battery is good healthy fully charged...
whats your battery voltage... getts it on a tender now...
j o
Post by: Zfoster8 on November 02, 2019, 08:05:01 PM
Post by: Zfoster8 on November 02, 2019, 11:32:47 PM
Post by: volador on November 03, 2019, 12:05:02 AM
Two interlocks interact: It should start if it is in neutral; or if the clutch lever is pulled if in gear. The clutch switch mounted on the clutch lever perch.
There is a transmission gear position indicator switch on the transmission rear.
So, if in gear pulling the clutch should allow it to crank. If not, the clutch switch is suspect.
If the neutral light fails to come on the TGPI switch seems faulty. If both get bad it won't start.
The "load shed relay" which has the headlight and some other stuff connected grounds to the hot brush of the starter. If the starter is not energized this provides a path to ground for the relay coil, thus providing current to the headlight, etc.
However, when the starter button is depressed 12v+ is applied to the hot brush. And the load shed relay coil now has 12v+ applied to both ends of the coil - thus no ground. So the relay turns the headlight and stuff off until the starter button is released.
https://forums.bmwmoa.org/showthread.php?94841-1990-K75RT-Electrical-problem
Starter motor cleaning / rebuild tutorial (http://www.k100-forum.com/t2342-starter-motor-cleaning-tutorial)
Main harness connectors under the tank
Choke switch: Violet/White and Brown
Clutch switch: Green/Black and Black/Green
Post by: Zfoster8 on November 03, 2019, 12:15:25 AM
In gear with clutch not pulled in does nothing at all, which confirms the switch works i suppose. Just went and checked.
Post by: Laitch on November 03, 2019, 01:34:07 AM
I guess my next steps are to start checking everything else, but does anyone have any recommendations on where to start?Consider checking the wiring junction marked by the magenta box on the left side of the attached diagram and the condition of the wiring marked by the magenta arrows in the diagram at the load shed relay.
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Post by: volador on November 03, 2019, 01:47:43 AM
Consider checking the wiring junction marked by the magenta box on the left side of the attached diagram and the condition of the wiring marked by the magenta arrows in the diagram at the load shed relay.Magenta such a pretty color. Where is my magnifying glass?Load shed:starter circuit.png (44.75 kB . 768x218 - viewed 683 times)
When you turn the key to on, you should hear (and feel) a click from the starter relay.You hear a click from the LSR
Post by: volador on November 03, 2019, 01:48:29 AM
Check your ground points 1- frame ground wire connection on the left side of the center frame tube under the gas tank
2- left foot peg plate area
Check for +12v power on the blk/grn wire at the starter button
The 9 pin plug for the right hand combo switch terminal #6(black/green) of that connector is the feed to the starter switch. the output of the starter switch (that goes to the starter relay coil connection) is terminal #1(black/yellow wire)
Next step would be to check starter relay coil +12v and ground, +12v wire is black/yellow and ground side is brown/blue.
Post by: daveson on November 03, 2019, 05:17:11 AM
But the lights don't cut out so the symptoms match what the PO told you, a failure at the starter relay. So check for constant power to 30, power to 86 with the start button pushed and earth to 85.
Does the starter relay click with the start button pushed?
Post by: The Mighty Gryphon on November 03, 2019, 01:02:10 PM
The condition of the starter brushes is critical. If I had starting issues with an unfamiliar brick a starter service would be the first thing on my agenda. You say the lights don't dim, which tells me the LSR isn't being pulled in, and that depends on current flow through the brushes, commutator, and the starter motor windings.
Post by: daveson on November 03, 2019, 03:53:05 PM
If, with the LSR removed, a click isn't heard or felt from the starter relay with a quick jab of the start button, that's a problem.
Post by: Laitch on November 03, 2019, 04:06:00 PM
Magenta such a pretty color. Where is my magnifying glass?Don't concern yourself with finding it. The response wasn't meant for you.
Post by: Zfoster8 on November 04, 2019, 08:49:05 PM
I will refer to the terminals of the starter relay by the listed numbers on the unit. Power in is 30, wire to starter motor is 87, wire to ignition module (?) is 85, two wires to other things are 86.
No load, key off
Battery - 12.9 volts
terminal 30 - 12.85
terminal 86 - 0
terminal 85 - 0
terminal 87 - 0
Key on, load shed clicked, starter relay did not click
battery - 12.32
30 - 12.26
86 - 1.0
85 - 1.05
87 - 0
ignition button pressed - lights still on, don't dim and fuel pumps running
30 - 12.16
86 - 10.0
85 - 9.85
87 - 0
I guess this determines that power is coming through everywhere it needs to, but the starter relay is not closing and transferring that power to the motor.
Post by: The Mighty Gryphon on November 04, 2019, 09:25:09 PM
Your readings make it look to me like there is a bad ground connection on the red/brown wire that goes from the starter relay to the ignition control module. It could be a broken wire, loose connection or a problem in the module.
A quick test to see if the problem is in the red/brown would be to run a wire from that terminal on the starter relay to ground. Then push the start button. If I'm right about the red/brown wire, the starter motor will spin.
Post by: Zfoster8 on November 04, 2019, 09:37:16 PM
The ground wire to the brown/red wire terminal worked, and i am so giddy excited. This is the first time the motor has spun over from the ignition switch the whole time i have had the bike.
Now i need to pull the tank off somehow and get a good look at that ignition module.
Post by: The Mighty Gryphon on November 04, 2019, 10:21:35 PM
Post by: The Mighty Gryphon on November 04, 2019, 10:30:57 PM
Post by: Zfoster8 on November 04, 2019, 10:33:37 PM
With the 85 terminal grounded, it seems i welded the connections closed on the relay and the starter motor kept running after the bike fired up. Had to disconnect the battery to get it to stop. Battery lead kept arcing to the terminal until i gave the relay a couple whacks.
The connector to the ignition module looks pretty good aside from being very dusty. The rubber boot was not on, and there was a good amount of gunk in there. I gave it a blow out and hit it with a cotton swab but I don't have any deoxit on hand, i will have to pick some up. after the brief cleanup, the problem is persisting, still not starting and now i am worried i might need yet another starter relay if it keeps welding itself closed.
As a layman who has never actually used a multimeter before this... what is the best way to check continuity on a single wire?
i will clean up that ground point on the frame, i did notice the brown ground wire coming out of the ignition module has some tape on it which makes me think it broke and was taped together. I will investigate this right now.
Post by: Zfoster8 on November 04, 2019, 10:51:49 PM
Post by: daveson on November 05, 2019, 02:36:30 AM
The starter relay jamming is a classic hallmark of a poor battery, maybe get it tested.
Post by: Laitch on November 05, 2019, 03:01:21 AM
As a layman who has never actually used a multimeter before this... what is the best way to check continuity on a single wire?Does that mean you've hypothetically used a multimeter? :-)
A Google or DuckDuckGo search will reveal plenty of videos explaining the process. Probes or clips are placed at either end of a wire. How continuity is expressed depends upon the multimeter's features—beeps, digit values, symbols, snippets of death metal, etc.. Spend fifteen to thirty dollars, follow the instructions.
Post by: The Mighty Gryphon on November 05, 2019, 08:25:03 AM
Put your multimeter on the lowest ohms scale(usually 200 ohms) and touch each end of the wire with one of the probes, then look at the reading. If there is good continuity the reading will be very low, near zero. Generally, with the cheap multimeters I use, a good reading is going to be less than 10 ohms, depending on how much resistance there is between the probe and what it's touching. It's a judgement call. Having said that, a bad wire will usually read thousands of ohms, or will have a blinking display.
Post by: Chaos on November 05, 2019, 09:49:51 AM
Post by: Zfoster8 on November 05, 2019, 09:54:44 AM
@Laitch - i actually had to watch a youtube video just to see what terminals to plug the wires into, because i had never touched one of these before i bought one. The internet is an amazing tool though, thats for sure.
You guys (and/or gals) really kick ass, thanks for all the help.
Post by: daveson on November 05, 2019, 05:31:35 PM
Post by: stokester on November 05, 2019, 07:36:59 PM
While an ohm measurement works for many quick checks it will read continuity even if only one strand of a multi-strand wire is remaining. If this is the case it will be unable to handle the load when energized. A better check for many circuits is to do a voltage drop measurement.
An internet search will bring up a number of pages on the how and why.
Post by: Zfoster8 on November 05, 2019, 08:09:01 PM
Post by: The Mighty Gryphon on November 05, 2019, 08:25:11 PM
Post by: Zfoster8 on November 05, 2019, 08:33:43 PM
Pardon my ignorance, but if it worked by grounding the terminal going to the ignition module, could i just run a permanent ground wire there? I want to tell myself no, because that seems like a bad idea but I am curious.
It seems like a bad idea because the starter relay (edited) keeps fusing shut and I have to whack it every time i push the ignition button to get the engine and starter motor to shut off.
My basic understanding is that the ignition module is providing a temporary ground to close the circuit and once the ignition button is depressed it stops grounding that terminal, is that too far off?
Post by: daveson on November 05, 2019, 10:59:13 PM
Post by: Zfoster8 on November 05, 2019, 11:00:56 PM
I do have a manual. Several actually. They are helpful, but not to the level that this website is.
Post by: daveson on November 05, 2019, 11:08:39 PM
The ICU allows earth through the brown/red wire to 85. Pressing the start button provides power through the black/yellow wire to 86 (and the fuel injection unit) This closes the contact in the starter relay from 30 (constant power from the battery) to 87 (power to the starter motor) so the starter motor turns. When you let go of the start button, power to the starter relay coil is lost, so the contact is broken, and the starter motor stops.
Post by: Zfoster8 on November 06, 2019, 11:37:57 AM
Post by: Laitch on November 06, 2019, 11:46:08 AM
I will work on trying to find some deoxit today. Doesn't look like any local stores carry it . . .Call a music store that sells amplifiers.
Post by: johnny on November 06, 2019, 12:04:28 PM
https://www.guitarcenter.com/search?fromRecentHistory=false&Ntt=deoxit
i uses the d5... cause its moar than a contact cleaner... that and the flushing action... better than plunging action...
Screenshot_20191106-111312.jpg (33.47 kB . 293x576 - viewed 595 times)j o
Post by: The Mighty Gryphon on November 06, 2019, 01:31:12 PM
That would tell me that the module is working as far as sending the spark signal to the coils. The question now is why there is no ground connection for the starter relay. I have been searching the internet for a circuit diagram of the module to see what may be affecting this ground but can't find any information about what is inside the module.
I suspect, but can't prove, that the module has some logic circuitry to turn off the starter relay once the engine is running even if the start button is held down. Now that you know how to check continuity, you might want to see if there is a connection between pins #11 and #15 on the module. I can't tell you where the pins are without the harness connector because they aren't marked on my module. You'll need to get the locations off the connector. It would be useful to know if and where there is continuity with pin #11.
I further suspect, but again, I can't prove, that wiring a hard ground from the starter relay won't hurt anything as long as you let go of the start button when the engine fires and starts running. That might be your 'plan b' if cleaning the connector doesn't fix the problem.
Post by: Laitch on November 06, 2019, 02:04:28 PM
Post by: The Mighty Gryphon on November 06, 2019, 05:49:48 PM
When the start button is pushed the starter spins and the load shed relay shuts off the headlight, the engine fires and runs. I keep holding the start button down as the engine runs. As the rpm's increase to idle speed, the headlight comes back on, indicating that the load shed relay is turning the lights back on. That means the starter has been shut off even though I'm still pressing the start button.
This tells me that the ignition module is sensing that the engine is running and shutting off the starter relay and the starter because it's not needed.
Going forward, I would try cleaning the connector and making sure it's tight. If the starter still doesn't work, you have the choice of purchasing an ignition control unit, or just running the starter relay red/brown ground wire to a frame ground and remembering to let the start button go when the engine starts. The sticky contacts you are experiencing in the starter relay may be the result of a weak battery or possibly a funky start button. I would also get in there and clean the relay contacts well to remove any burnt metal where they meet.
Post by: Zfoster8 on November 06, 2019, 05:59:21 PM
I appreciate you checking into that for me. That confirms my understanding of the ignition module's workings.
I am picking up some deoxit after work and I will see if that makes a difference. if not, for now I will run the hard ground wire and clean up that relay and give 'er hell for a while until i pick up an ignition module. We are heading into winter here anyway, so realistically I am getting the bike running so that it can sit for four months so I have all kinds of time to get this resolved. I was digging around on some other posts on here and I think i will end up buying an Odyssey Extreme PC680 battery. I suppose shooting some deoxit into my ignition button wouldn't hurt anything either.
Post by: The Mighty Gryphon on November 06, 2019, 06:05:40 PM
Post by: Laitch on November 06, 2019, 06:11:38 PM
Post by: Zfoster8 on November 06, 2019, 08:46:23 PM
To update everyone, I picked up some deoxit and blasted the connector and all the pins for the ignition module to no avail. No change. I ran a straight ground wire from the 85 terminal to the engine case ground above the shifter. picture attached.
I inspected the old starter relay and aside from the case being a bit busted up it is in fantastic shape so i swapped it in, and later on i will inspect the new bosch unit i had in there that was fusing shut.
I just rode the bike completely under it's own power for the first time!
Thanks everyone, and I will keep working on it because I would like to have the safety feature of the starter not running because i have been known to do something stupid like push the starter.
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Post by: The Mighty Gryphon on November 07, 2019, 08:05:48 AM
I'm sure there are hundreds of posters here who will disagree, but personally, I think that start interlock in the ignition module is another case of Teutonic overthinking that leads to more problems than it cures.
The sprag won't engage unless the engine is turning less than 300rpm, a situation that is virtually impossible. While the engine is running the sprag ring is already spinning at half the rpm of the crank shaft. Pushing the start button just reduces the speed difference between the inner and outer rings by 300 rpm. Not really significant when the one of them is spinning at 3 grand.
The only thing that might happen from riding around holding the start button is that you'll heat up the starter motor. I wouldn't hesitate to use the external ground wire while I looked for a good deal on an ignition module.
Post by: Laitch on November 07, 2019, 08:15:20 AM
. . . aside from the case being a bit busted up it is in fantastic shape . . .That is a description that begs for elaboration. Could describe how good shape would differ from fantastic shape? :-)
Post by: Zfoster8 on November 07, 2019, 10:00:03 AM
Or maybe like a disney princess would say, it's what is inside that makes it beautiful.
Either way, i am just happy it works!
Post by: daveson on November 07, 2019, 05:14:25 PM
What does that after market switch on your dash pad do.
Try the deoxit again. Since the cover was off, this deserves extra attention. Deoxit, scrub it, clean it, deoxit it again. Push it in and out the ICU a few times so the socket gets a spray as well as the pins. Then clean it, then make sure it's dry before plugging it back in. Don't know if the brown wire was rested for continuity.
If the new wire was earthed at the ICU pin for the brown/red, instead of the gear box, could that fix it? I realise I spose the Amps would be tiny, so unlikely, but still.
I'm wondering how the multimeter was used on the bike for the third test at pin 85 (with the result of 9.85V)
Hopefully not much fuel got past the rings, into the oil, while these tests were run with the fuel pump on.
Post by: Zfoster8 on November 07, 2019, 07:26:37 PM
Currently the switch does nothing but take up space. it was one of the "upgrades" the previous owner started and never followed through with, there are not even any wires connected to it.
I will keep messing with that connection and keep an eye out for a decent priced ignition module, i would like to have the bike as factory-functional as possible for the sake of being able to know what is going on with it at any given time.
your suggestion of grounding through the ICU instead of gear box, do you mean cutting the new wire into the old one? it is a possibility but I got good continuity through that wire so i didn't see any reason to think there was a broken connection there.
The multimeter was used with the following method; meter set to Ohms (200), black terminal touched to ground (same engine ground the wire is connected to now), with the red terminal touched to the 85 terminal, and the 9.85V reading came when the ignition button on the handlebars was pressed.
The bike is going in for an oil change, fuel injector cleaning, and drive shaft oil change in the next week or two anyway, so hopefully there will be no ill effects between then and now.
Let me know if i can elaborate on anything else, i was definitely flying by the seat of my pants through most of this.
Post by: daveson on November 07, 2019, 09:51:36 PM
Post by: Zfoster8 on November 08, 2019, 11:35:28 AM
I would seriously doubt my multimeter's abilities if i got a voltage reading in the ohms setting.
Post by: Laitch on November 08, 2019, 12:14:44 PM
The bike is going in for an oil change, fuel injector cleaning, and drive shaft oil change in the next week or two anyway, so hopefully there will be no ill effects between then and now.Are you performing the oil change and sending the injectors out for cleaning? What is meant by drive shaft oil change—changing the oil in the final drive, removing the final drive to lubricate the pinion gear shaft splines, or what?
Post by: Zfoster8 on November 08, 2019, 02:55:06 PM
I was under the impression that the final drive shaft had it's own oil reserve for lubrication and I am going to venture a guess that it has never been changed.
I am not sure if i will have them go so far as to pull the final drive apart, but it would be a good idea. I will see how much they will charge to do that and weigh it against how difficult it is for me to do by myself in my garage.
Post by: daveson on November 08, 2019, 03:51:46 PM
Post by: johnny on November 08, 2019, 03:52:17 PM
i would not take it to a bmw factory dealer...
if you dont wanna f with it you oughtta think about an independant wrencher...
if you just gotta take it to a oe dealer... id take ot to craig hansen (https://www.hansensmc.com/)down the superslabb aways from yous...
j o
Post by: The Mighty Gryphon on November 08, 2019, 04:00:29 PM
greetings...
i would not take it to a bmw factory dealer...
if you just gotta take it to a oe dealer... id take ot to craig hansen (https://www.hansensmc.com/)down the superslabb aways from yous...
j o
+1 Dealer techs aren't trained on Classic bricks, and don't have the time to figure them out. You are better off doing routine maintenance yourself. You'll save a bucket of cash, and you'll know the job was done right. It's not really that hard.
Post by: Martin on November 08, 2019, 04:04:44 PM
Regards Martin.
Post by: Laitch on November 08, 2019, 04:34:04 PM
I am not sure if i will have them go so far as to pull the final drive apart, but it would be a good idea.It would be a bad idea. The only time a final drive is "pulled apart" is if a bearing or other part within it needs to be replaced. Maybe by "pulled apart" you mean detached from the swing arm.
The final drive is lubricated by its own oil supply—drain old fluid from the bottom, refill from the top with a measured amount; check with a dipstick. To lubricate the final drive input shaft splines, the drive is detached from the swing arm that houses the driveshaft. That's a four-bolt operation. The final drive input shaft splines are cleaned then a lubricating paste is applied by hand. The input shaft splines are connected to the driveshaft output socket splines; the lubrication is shared.
These are the most basic of maintenance operations. They can be performed with the moto on its centerstand.
Post by: Zfoster8 on November 08, 2019, 04:43:32 PM
For some reason this bike is intimidating to me from a mechanical standpoint, but after reading around in the service manuals and from these replies I think i would be just fine to do probably all of the work myself.
Something about a small car engine being shoe-horned into a streetbike frame is super exciting but makes me think it will be really hard to work on. Time to put on my big boy pants and start putting in the work.
Post by: Martin on November 08, 2019, 07:03:13 PM
Regards Martin.
Post by: Past-my-Prime on November 08, 2019, 10:34:11 PM
I don't have a dipstick for that. I'm pretty sure it's just fill to the bottom of the fill-hole on the final drive.
The final drive is lubricated by its own oil supply—drain old fluid from the bottom, refill from the top with a measured amount; check with a dipstick.
To lubricate the final drive input shaft splines, the drive is detached from the swing arm that houses the driveshaft. That's a four-bolt operation.
It was more like a 12 bolt operation for me or maybe 13. Only the very last part was four-bolts!!
Remove wheel, remove brake calipers, detach ABS sensor, take out speedometer speed sensor, detach rear spring, remove final drive from swingarm . . . maybe I was doing it wrong?
Anyway it was lots of fun if you manage to forget what I found when I looked in there :shudder
Post by: Laitch on November 09, 2019, 06:46:38 AM
I don't have a dipstick for that. I'm pretty sure it's just fill to the bottom of the fill-hole on the final drive.As long as you're pretty sure; that's what counts. To me, it's just bolt-and-unbolt—a degree of difficulty next to zero, thankfully. :-) I'm still working on arithmetic skills. :-)
It was more like a 12 bolt operation for me or maybe 13. Only the very last part was four-bolts!!
Post by: The Mighty Gryphon on November 09, 2019, 08:13:30 AM
I've said it before and I'll say it again, maintenance is is like foreplay, take your time, pay attention, and enjoy doing it. The ride is your reward.
Post by: stokester on November 09, 2019, 12:29:55 PM
Don't be intimidated by the mechanicals. A major reason I have three in the garage right now is that they ere really pretty easy and satisfying to work on. Just relax and take your time.I only have two bricks but also have two airheads for the same reason.
I've said it before and I'll say it again, maintenance is is like foreplay, take your time, pay attention, and enjoy doing it. The ride is your reward.
I've found both models easy to work on with an avid following that willingly share expertise and assistance.