BMW K bikes (Bricks)

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51Back to top Go down   Electrical gremlin - Page 2 Empty Gremlins Mon Apr 19, 2021 6:55 am

daveyson


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I don't think so cause my test bike doesn't have electrical issues. For a long time I thought Dave had a power problem, I was surprised by the results from removing pin 13 from the circuit. By the way, removing pin 23 (another earth) had the same results, so that maybe wants a look see too.

The tacho remained at 0 for about six seconds. Now it then goes from there to 6,000rpm then settles down to about 3,000. Since Dave's problem often doesn't last that long, I guess the tacho symptom only happens sometimes.

With my brick I got the following lights on the cluster:

Pin 13 removed, Key on, light switch off; low fuel, neutral, high beam, oil, battery, drunk tacho. 

Pin 13 removed, key on, light switch on; high beam, oil, battery, top back lights (so no low fuel light even if the fuel is low) 

The choke light worked in both cases, but not with pin 6 (power) removed, which is to be expected.

    

52Back to top Go down   Electrical gremlin - Page 2 Empty Re: Electrical gremlin Mon Apr 19, 2021 11:03 am

Holister

Holister
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Some of these symptoms sound a little like what happens when the battery runs low and the starter relay fries itself.
You could have some low voltages due to a poor battery or maybe your alternator is not outputting the 14v the system needs. Check the charge voltage across the battery terminals with the motor running at 2k rpm. Sometimes the voltage regulator/brushes just needs a clean but if the voltage is low then it's an easy replacement.
The battery voltage after a good charge and a 12hr rest should be reading close to 13v.


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1989 K100RT     VIN  0097367 (naked)  
1996 K1100RS   VIN  0451808
  Electrical gremlin - Page 2 Austra12    Fuel:  95 Octane
Engine Oil: Nulon Full Synthetic 15W50
Gear Box Oil:  Nulon Synthetic 75W90
    

53Back to top Go down   Electrical gremlin - Page 2 Empty Gremlins Wed Apr 21, 2021 9:59 am

daveyson

daveyson
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Maybe this is better than my earlier idea. Next time it cuts out, turn on the choke switch. If the choke light comes on, points to bad earth. If it remains off, then comes on with the neutral light, points to a power fail.


__________________________________________________
11/1985 bmw k100rt (late model)  Vin. 0090567
 ~120,000 km
    

54Back to top Go down   Electrical gremlin - Page 2 Empty Re: Electrical gremlin Wed Apr 21, 2021 11:17 pm

davemadsen

davemadsen
Silver member
Silver member
@daveyson wrote:I don't think so cause my test bike doesn't have electrical issues. For a long time I thought Dave had a power problem, I was surprised by the results from removing pin 13 from the circuit. By the way, removing pin 23 (another earth) had the same results, so that maybe wants a look see too.

The tacho remained at 0 for about six seconds. Now it then goes from there to 6,000rpm then settles down to about 3,000. Since Dave's problem often doesn't last that long, I guess the tacho symptom only happens sometimes.

With my brick I got the following lights on the cluster:

Pin 13 removed, Key on, light switch off; low fuel, neutral, high beam, oil, battery, drunk tacho. 

Pin 13 removed, key on, light switch on; high beam, oil, battery, top back lights (so no low fuel light even if the fuel is low) 

The choke light worked in both cases, but not with pin 6 (power) removed, which is to be expected.
How do I “remove Pin 13”....or any pin from the instrument cluster?


__________________________________________________
Dave
    

55Back to top Go down   Electrical gremlin - Page 2 Empty Re: Electrical gremlin Wed Apr 21, 2021 11:41 pm

davemadsen

davemadsen
Silver member
Silver member
Re instrument cluster: I cleaned and DeoxIT’d the male pins (unaware of how I can clean the female terminals so just DeoxIT’d them)

After reinstalling the cluster, I turned the the key and I got the failing instrument lights and drunken tach for about 2 seconds and then - without any intervention on my part - the lights came back on, all became right in the world, and the bike promptly started.

Then I pulled apart the ignition switch and found it in near pristine condition: contacts glowed like gold. In any case I sanded the contact surfaces and reinstalled the switch.

At this point the bike is behaving perfectly. Of course the bike behaved perfectly for the past five months - until it didn’t.

I am carrying around a list of what lights and conditions should exist (or not) so the next time the bike quits, I will have a checklist and will be able to report back (and maybe even work toward resolving the issue).

Thanks to each of you for your input.
Dave


__________________________________________________
Dave
    

56Back to top Go down   Electrical gremlin - Page 2 Empty Re: Electrical gremlin Thu Apr 22, 2021 9:44 am

Point-Seven-five

Point-Seven-five
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Life time member
cheers Here's hoping you finally found your problem.

The ignition switch needs clean contacts and a bit of pressure between them to function properly. In my opinion, the pressure applied by those little springs leaves much to be desired. Giving the switch a clean reduces the pressure needed and frees up the springs to work a little better.

Clean looking contacts can still be a problem. They don't need to be black and heavily burned to cause problems. Because of the low force pushing them together, the slightest bit of corrosion will mess up the operation.


__________________________________________________
Present:
1994 K75RT
1991 K100RS
1988 K100RS SE

Past:
1994 BMW K75S
1992 BMW K100RS
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

57Back to top Go down   Electrical gremlin - Page 2 Empty Re: Electrical gremlin Thu Apr 22, 2021 12:14 pm

davemadsen

davemadsen
Silver member
Silver member
I polished the ignition contacts.

Two additional pieces of information (this is like a puzzle, huh?) are as follow:

When bike died, the 4-way flashers would not work.

When the bike died, I was on a slight downhill. I thought I would bump start the beast and coasting along about 5 mph I attempted a bump start. Engine just turned over as if the ignition was off.

Dave


__________________________________________________
Dave
    

58Back to top Go down   Electrical gremlin - Page 2 Empty Gremlins Thu Apr 22, 2021 10:38 pm

daveyson

daveyson
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Life time member
I removed pin 13 from the circuit by cutting a piece of thin glossy cardboard the width of the pin, and a little more than twice its length. Electrical gremlin - Page 2 Img_2035


And pushed it in its socket. Electrical gremlin - Page 2 Img_2036
 
 Yeah it's the lazy way. 

I only did it to see if it would reproduce your symptoms but the drunk tacho seems to have more to do with the light switch on, than earth. 

So the lights (plural)  cut out, so that points to a power fail, as does the hazards fail. 

So if all the fuses and sockets are clean and tight, I'd also look that the wires are all pushed in the same length,behind the fuses and sockets.

Your hazard problem is probably related to your previous turn signal problem thread, which I guess you still have. The flasher unit gets power from fuse three, and also from the load shed relay through fuse seven.


__________________________________________________
11/1985 bmw k100rt (late model)  Vin. 0090567
 ~120,000 km
    

59Back to top Go down   Electrical gremlin - Page 2 Empty Re: Electrical gremlin Fri May 07, 2021 9:43 pm

davemadsen

davemadsen
Silver member
Silver member
Based on previous comments, the following additional information was gathered when the bike quit yesterday:


Choke light did not come on.

4-way flashers were inoperable 
Three dummy lights - oil pressure, temp, and voltage all lit. 


As bike started to return to normal (maybe 20 seconds),
gear indicator went from blank to on - but flickered in rhythm with the 4-way flashers which began to function.


__________________________________________________
Dave
    

60Back to top Go down   Electrical gremlin - Page 2 Empty Gremlins Fri May 07, 2021 10:01 pm

daveyson

daveyson
Life time member
Life time member
The choke light was also off, so points to a power fail, probably from the ignition switch or kill switch.

If the kill switch is failing, the horn, indicators, hazards and head light will still work (but the brake light won't) 

Since the flashers don't work, it's probably the ignition switch.

Having too many keys on the key ring might be a problem. If wiggling the key makes the power cut in and out, that pretty much wraps up the cause.


__________________________________________________
11/1985 bmw k100rt (late model)  Vin. 0090567
 ~120,000 km
    

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