power loss on R100GS
 

I'm really inexperienced at this stuff, particulary in regard to electrical/ignition issues. I'm desperate for help.

Initially I was riding my 92 R100GS about 10 miles, when the bike just died as I was riding it. When I tried to re-start it, the engine turned over, but it wouldn't fire up. It turned out that the there was no spark at the plugs.

In trying to troubleshoot why the plugs were not sparking, I made a very stupid and rash decision. The plugs in the bike are Bosch Super RO 668's. This morning, suspecting that something might have been wrong with it, I removed the right cylinder plug and replaced it with an older one, a Bosch RO 948. I left the 668 in the left cylinder and fired the bike up. It turned … and then I lost all power a second later, and still don't have any.

Now when the key is turned on and the kill switch is also on, I get an intermittent electric buzzing sound from one of the relays. But with the kill switch off, no buzzing.

My question: Can anyone please tell me what I might have screwed up by doing this? How I might be able to restore power?

Please help.

Thank you.

Sounds like you need to replace the relay but I am no mechanic. I found this article that might be of some use.

BMW Airhead Motorcycle Electrical Hints

One of the two black relays is making the buzzing sound. So I removed it and replaced it with a new one.

Still no power.

hmmm....That's a head scratch-er. It should run with just one spark plug firing albeit very badly but it should still run. The only other suggestion I have is to try replacing the other spark plug. Check all electrical connections on the battery terminals. Make sure there is no corrosion. Other than that you may have to take it to the shop.

I wasn't getting any sparks at the plugs before the power failure; that was the problem I was troubleshooting when I fu..ed up and turned the bike over with the two different plugs, causing the power failure.

After the power failure, I replaced both plugs with new ones. Same problem. And yes, I learned from my costly mistake in that I put two identical plugs in.

The last thing I want to do is bring it to the shop. I ain't fond of bending over.:censored:

Basics



Is there battery voltage at the ignition coil? (No.. then fault find that.)

Is the battery voltage above 12.5 volts? (If the battery is flat you won't get spark.)

Flick the kill switch back and forth between 'on' and 'off' - get spark? (Spark indicated ICU and battery connection ok.)

Is there spark when the HES (bean can) connectors central pin is shorted (and then opened) to earth? (connector under front engine cover, disconnect battery negative to avoid shorting out the diode board - then reconnect the battery negative for testing. Disconnect the HES and short/open the central pin of the connector that runs upwards to the ICU.)

================================ Caution =============== Applies to any electronic ignition ===
You can blow up the ICU if you operate the bike without the spark plugs attached (and their bodies connected to the bike - providing an electrical contact back to the battery negative)

Is the battery voltage above 12.5 volts? (If the battery is flat you won't get spark.)

Yes. 13 volts.


Is there battery voltage at the ignition coil? (No.. then fault find that.)

NO. (some, but in millivolts.)

How do I fault find that?

By the way, the ignition coil is brand spanking new. Also, when I initially only had the problem of no spark at the plugs, I WAS getting voltage to the coils. Now, after fu..ing up by putting two different plugs in the bike and turning it over which resulted in the power failure, there is NO voltage to the coils.

There are 4 terminals on the ignition coil;
2 are the HT leads to the spark plugs.
1 goes to the battery through the engine kill switch then on to the ignition key switch and probably a fuse
the remaining one has 2 small black wires on to, one wire goes off to the tachometer, the other wires goes off to the ICU.

Both of the smaller wires should have battery voltage. The ICU wire will pull the battery voltage down towards 0 for some time .. say 30 seconds while it waits for the motor to start up. If the motor does not start up then it should release the voltage back up towards battery voltage. Test the other terminal for battery voltage .. if it is not there then you probably don't have the warning lights either (alternator and oil pressure)? If not then look at the engine kill switch, ignition key switch fuse... If you have the lights and not battery voltage on the coil then the wires/connections between the two need to be looked at.

Warning:
The coil terminal with the two small black wires .. when the bike is running there is a large AC voltage here .. some 300 volts ... best to keep fingers away from this. Only meaure here when the engine is not running .. and after say 30 seconds of it being stopped.

Thank you very much for your help with this, Warin.

I am going to proceed, very slowly and deliberately, to try to digest what you've said and then go about testing what you mentioned.

This will take me a while. I will update throughout the day as I find out material information.

I really appreciate your help.

I have no telltale lights, nor headlights ... no lights whatsoever.

I began with the ignition switch. Trying to follow Clymer's instructions, I disconnected the ignition switch electrical connector from the wiring harness. Then Clymer says to test "the indicated wires in the switch side of the electrical connector and check for continuity in all switch positions."

I have attached a picture of the switch-side connector to make sure I have the right part.

Two things:

1) There are no "wires in the switch-side" of the connector, just 4 receptacles for the pins coming from the wiring harness.

2) I have no idea what I'm doing, of course, but here's what I did anyway. I set my multi-meter to Ohms and placed the two probes in all 6 combinations possible. I got 0 Ohms in every instance. I also repeated this where the wires of the switch are soldered underneath the key ignition mechanism at the dash, and got 0 ohms as well.

Did I do the right thing? And if so, does that mean the ignition switch needs to be replaced?

Or did I not test for continuity correctly? If not, please tell me how to test the disconnected switch-side with the multi-meter.

Thank you.

When you say 'power loss' ... I think you have lost engine power ... not electrical power ... remember I cannot see what you see so have to rely on what you type. :oops2:


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Check your fuses. Do this by looking for battery voltage on each side of the fuses. Ignition key switch on - this should power up the fuses.

If only one of the 3 fuses has power then the key switch is suspect, or the wires to/from it.

If a fuse has power on one side and not the other then that fuse may need replacing.

----------------------------
Looking at your wiring diagram ... if the starter motor is turning over you must have power to the ignition coil ...? And that should power the warning lights! Something does not make sense here. Finding the common link to the other lights (brake light, headlight etc) is the challenge.

================= Edit ====
Errr while I'm concentrating on the battery supply .. should also consider the battery negative!

There should be a lug with a few brown wires connecting to earth .. usually on a bolt for the ignition coil mounting. Check that it there and tight.

Then I misspoke.

What I have is complete and utter electrical failure.

At first, my problem was not being able to get the bike started. At that point, there was voltage to the coils, all lights were working, and the engine was turning over. The problem was there was no spark at the plugs, so the bike wouldn't start, and that was the problem I was initially troubleshooting.

Then, after I turned the bike over with two different plugs (while I was troubleshooting the initial problem), that is when I experienced complete electrical failure. I thought "loss of power" conveyed that. I was wrong. I apologize.

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Please forgive me Warin, but I am even more lost than usual here. As far as I know, there are 4 fuses on my bike. They are of the spade variety, 15A, located on the side of the battery.

Are there other fuses on my bike (i.e. 1992 R100GS) I'm unaware of? I've looked at Clymer and Haynes for additional fuses, but can find no others.:(

No need .. just explaining my confusion :(


Me again... must be the cool mornings :oops2:

Was using a different year ... Ok 4 fuses spaded

Measure the voltages .. on the spades there is a bit of metal showing on both ends .. measure on both ends - should be the same on both ends .. if not = blown fuse.

------------------
One fuse will have battery voltage at any time,
two with the ignition key switch on
the remainder with the ignition key switch on and the headlight switch on

So turn on the ignition key switch on and the headlight switch and test those fuse voltages.

I already suspected that I blew a fuse, so I removed all 4 and looked at them. They looked fine. But just to be sure I replaced all 4 with brand new ones. (I guess I should have mentioned that already. Sorry again.) Of course, the new fuses didn't help. Still got nothing.

And just to be clear, as I stated above I replaced the spark-plugs with brand new, identical ones (after the botch with the different plugs which preceded the electrical failure). No help here either, of course, again.

Now, I am again thinking of the ignition switch. When I turn the ignition on and the kill switch off, I get absolutely nothing. But with the ignition on and the kill switch also on, I get an intermittent buzzing/clicking at one of the black relays.

(By the way, I already removed both black relays and replaced them with two brand new ones I had lying around. Didn't help.)

So, now do I focus on the ignition switch, like I started to before? Or the kill switch? Something else?

Thank you, Warin. You're a lifeline.

The spade fuses .. do they have a small area on top at each side where there is a bit of metal showing? This is with the fuses in the holder .. just look at the exposed tops. Use that area to measure the voltages on each fuse - ignition key switch on, headlight switch on.

This will tell you if there is battery voltage;
before the ignition key switch
after the ignition key switch
after the headlight switch

The spark plugs have nothing to do with the lack of headlights.

Before looking at the fuses, and I decided to test the ignition switch to see what I could find.

I disconnected it from the wiring harness and started testing with a multi-meter. Then, after re-connecting the switch and turning on the ignition, BOOM ... I've got lights, telltales, everything ... and the bike is once again turning over.:clap:

Any ideas why?

Now I'm going to once again test at the coils to resume troubleshooting why I'm getting no spark at the plugs.

Thanks Warin.

This kind of fault is called an 'intermittent' .. it will come back .. then disappear .. only to reappear. Of course it will reappear at most inconvenient times.

It could be a loose connection .. the earth lug for the wiring harness not being tight for instance. It could be lot of things.

Ok. I think I have posted what to do about that above.

When an intermittent occurs your best off trying to isolate where the fault is.

If you test something and find it OK .. you still don't know if the fault is within the thing you tested, particularity if the fault disappears after the test as the fault may have disappeared just before you started the test.

What I think should be done is trying to find where the voltage disappears with minimal disturbance to things. By testing at the fuses you find out if the voltage is getting to the fuses, getting past the ignition key switch and getting past the headlight switch. That is 3 things for one group of tests in one location, minimum work and disturbance for a fair amount of information.

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Same for the ignition system.

Check for sparks as you flick the engine kill switch on and off (the warning lights should come on and off .. if they don't you have a problem that does not involve the ignition system itself but the supply to the ignition system.

If no sparks and warning lights working above then

Check that the central pin short/open of the HES connector causes spark (as detailed in another post). If you get sparks here it would suggest the HES is faulty. No sparks suggest the ICU/coil or supply problem.

Glad to hear you got it going. Hope you isolate the problem and get it permanently fixed. Best of luck.

Today, Tuesday, I have a full day devoted to other tasks which have been neglected since I've been at this. I will be back at this Wednesday morning.

Thanks Warin.

I tested the fuses. You said "one fuse will have battery voltage at any time, two with the ignition key switch on the remainder with the ignition key switch on and the headlight switch on." You were right in that one did have voltage at any time, all 4 with both the ignition and headlight switches on, but only one fuse had voltage with just the ignition on, which was the same one that has voltage all the time.

I also troubleshooted the coil like you said. I disconnected the black lead to the primary coil, laid the base of both spark plugs on the cylinder heads with the HT leads connected, then jumpered the disconnected primary-coil terminal intermittently to ground with the ignition on and kill switch off, and got no spark at the plugs.

I also did as you said and jumpered the middle receptacle of the beancan-plug connector to earth intermittently with the ignition on and kill switch off, no spark.

Anyway, I will confess right here what else I did. Frustrated to no end, I bought a used beancan and a used ICU and installed them. Remember that I also have a new coil too. Add to that new HT leads, new plugs and new fuses.

All lights work, the engine turns, but I STILL CAN'T GET THE BIKE STARTED!

What the hell, Warren. What else can I do?

?
If the kill switch is off ... you won't get spark.

For testing (and running) you have to have
the ignition key switch ON
AND
the engine kill switch ON

Take a break and relax ... I think your stressing out .. I do that too. :(
----------------------
Just because something is "new" that does not mean it works.

----------------------------
Ok fuse voltage readings indicate the key switch is working.

Do you have battery voltage at the coil? - the smaller leads not the large HT leads that go to the spark plugs. That would confirm the the switches are ok and that the leads to this point are ok.

Then test the coil by shorting the negative terminal - the one with the two small black wires going to it.
No spark means fault in the coil or the HT leads or the spark plug caps or the spark plug.

Warren,

when I said the kill switch is on, I meant that it is set to one of the two positions that make starting the bike impossible.

When I said it's off, I meant that it's in the middle position, where it needs to be to start the engine. I apologize, again, for another instance of this flustered newbie not speaking correctly, though I believe I did do this test correctly.

Do you have battery voltage at the coil?

Yes.


Then test the coil by shorting the negative terminal - the one with the two small black wires going to it.

I did that twice.


No spark means fault in the coil or the HT leads or the spark plug caps or the spark plug.

Like I said, all of these things are brand new. Maybe I fu..ed up the new coil somehow. I'll throw the old one back in tomorrow and see if that changes anything. It won't, though. The resistances of the two units are identical.

And I've already tried two sets of plugs -- the ones that were in the bike when it went down and then two new ones.

You said that just because something is new doesn't mean it works. So, how do I test the HT leads? The caps?

And please disregard the attached picture. I answered my own question about it.

Thank you.

Test the HT leads ..

you can test for continuity

From the coil connections to the spark plug connections .. should be about 5,000 (or 5k) ohms. That is 5000 for each lead + cap , disconnected from anything else. They can be more if someone has used resistive lead - that could add another 5000. As long as it is less than say 15,000 and more than 4,300 ohms each that would be ok.

How old are they? If more than 10 years I'd replace them.
You cannot test for insulation .. well not with your normal DMM. This is the resistance from the inside to the outside and must be OK at a very large voltage .. say 20,000 volts .. your DMM only has around 9 volts. Testing at 9 volts will not reveal what happens at 20,000!
I prefer the solid copper leads rather than the resistive ones myself. Then I use NGK 5k resistive caps.

======================== Logic?

Yes, we have no bananas ... means? Are you French = no bananas, English = yes we have bananas.
Nay? Dutch = No. Greek = Yes.

Warren,

your help here should prove to be invaluable.

I tested my new leads as you described. I got 1K ohms.

I bought the wrong leads.:clap:

When I bought them, I merely asked a man at Euro MotoElectrics if they fit the new coil I was also buying from him. He asked me for the make and model of my bike, I told him, and after some hemming-and-hawing he said they would work.

They don't.

My fault, though. My temper is the bane of my existence, and if I didn't get as flustered as I do at times like these it would have dawned on me to get the part# I needed and verify it was the same as the leads I bought.

So I am over-nighting the correct leads. Tomorrow, Friday, I will install them. Whether or not the bike starts afterward, you'll be the second person to know.

Sincerely,

Shithead:stupid:

Got the new leads.

Both tested at 5K ohms.

Put 'em in.

Guess what?

NOT A FU..ING THING!!!!!!!!!!!!!!!!!!!!

Driving it to the mechanic today. 250 mile round trip, and I ain't looking forward to it.

God hates us all.

The problem is solved.

A bad diode in the wiring harness.

Thanks again for all of your help, Warren. I really appreciate it.

Until next time ...