I just bought a K100RT. I got it for a song because it has been blowing the #1 fuse. I figured it would be easy to find what was obviously a dead short - but it turns out it isn't so simple.

Fuse #1 powers:

rear brake switch
front brake switch
clutch switch
heated grips
optional accessories
optional gauges
the dash

I installed my ohm meter on the neutral side of the fuse block and had continuity with the frame. I then unplugged each connector in turn (there are no optional accessories or gauges) and the dead short remained until I unplugged the dash.

Only it didn't go away right away...it would come and go when I pulled on the harness going to the dash.

So I stripped off the insulating tape - all the way back to the relay box - but damned if I could not find any burned wire or cracked insulation. One things for sure though - once I stripped off the insulating tape to the Y where the main harness forks to the right and left the dead short disappeared and stayed gone.

So I replaced the suspect stretch of wire - and I re-soldered the green/blk wire node. In fact I split it into two wires with connectors on the end to aid in troubleshooting. Long story - difficult and pointless in describing it in detail.

Cut to the chase - the wiring is sorted - the harness taped back up. Nice job if I do say so myself and the dead short is gone. :cyclops:


THEN - I plugged the dash back in and wouldn't you know it the dead short is back . Unplug the dash and the short goes away. Plug it back in and the short returns. Unplug it and the short goes away. Huh.

Pull out the ohm meter again and sure enough I have continuity between pin #6 (power in) and pin #13 (ground).

It looks like I had two problems - one of which may have caused the other and one of which I think I fixed. I'm riding the bike now without gauges and so far so good.

So question one for you lads is whether this is something that happens a lot or if this is relatively rare. I think I know the answer because I can't find a lot written about it. I should point out that the bike came to me this way so I can not tell you what the dash was doing prior to the fault. I've never ridden this bike with a dash installed.

Question 2 is whether there is a good writeup anywhere for troubleshooting this dash. I have had it apart already - and I don't see anything obviously wrong. All of the writeups I've seen talk about moisture getting in and I don't even see any evidence of that.

So...suggestions?

thanks

jasper

Just looking through the circuit diagram I would be unpluging the gear indicator switch from the harness . The plug is a 4 pin with 3 yellow/colour and a brown earth, it's behind the right side cover. The switch does give trouble and is connected into the #1 fuse. Next remove the circuit board associated with the gear indicator from inside the instrument cluster. Its a likely place to look but no guarantees as with something like this it is more a series of eliminations till the culprit rears it ugly head.

RicK G wrote:Just looking through the circuit diagram I would be unpluging the gear indicator switch from the harness . The plug is a 4 pin with 3 yellow/colour and a brown earth, it's behind the right side cover. The switch does give trouble and is connected into the #1 fuse. Next remove the circuit board associated with the gear indicator from inside the instrument cluster.  Its a likely place to look but no guarantees as with something like this it is more a series of eliminations till the culprit rears it ugly head.

Thanks Rick - it's a good a start point as any.

cheers

All right Rick!

Nailed it.

Check out the photos of my gear indicator board. crispy is the word I'd use. Note especially the burned up circuit from terminal 31 to capacitor 22. The rest of the board doesn't look much better, including the circuits that run to the display itself.






I suspect the short that was in the wiring loom overloaded this piece. That's why the two problems at once.


So the question now is whether I can run this dash without that board in place. Most importantly whether the signal and neutral indicator lights will work. Those are important to me at the moment because I'm commuting.

I'll post back and let y'all know.

I could also ask if these boards are available still....or more importantly where I'd find one.

OK - well after all that I think I just spent the night chasing a ghost.

Even with that gear indicator board out of the way I still showed continuity between pin 6 (hot wire in) and pin 13 (ground).

I started looking at the turn signals - and noticed that the ribbon feeding the left side indicator was badly kinked. Then I convinced myself it was shorting out even though it didn't look burned. I thought it was the bulb - and changed that but realized that yes of course it would be a circuit through the bulb - that's how they work duh

But the ribbon was badly kinked so I cut it out and soldered in a fine wire instead - once again a pretty tidy job....but pointless as it turned out - read on.

I didn't see any continuity between pin 6 and 13 anymore so I figured I had it beat and screwed the whole thing back together. Then I checked one last time and damn it - there was the short again. So I take it all apart again - take out the gear indicator board - find that there's continuity between the positive and ground on the tachometer....this is getting weird.

So FINALLY - I go over to the K75S which is sitting there watching and snickering away. It's running fine thank you very much - and I pull out the number 1 fuse and check the resistance between the neutral side of the fuse holder and the frame - and sure enough...it's absolutely normal to have no resistance - or very little - between this fuse and ground. The instrument cluster is a conductor. That's ow it works.

SO...I screw it all back together again - mount it up to the K100 and turn on the ignition.

The dash lights up, gear indicator says I'm in first - which I am. I shift to neutral - it shows 0 and the neutral light comes on. I start the bike - it runs. I shut it off, I set the clock....all is normal and as it should be.

Still a fun way to spend the evening I guess...and that ribbon was kinked which I fixed....

Oh Vell - hopefully it doesn't blow a fuse anytime soon. That would be nerve wracking.


Thanks for the support guys.

Pin #6 is the ground (earth) for the coolant temperature warning lamp. It is not "Power in"

Coolant temp warning lamp is connected via pin #10.
Switched power in at #6 is correct.

Ok....I know better than to doubt Inge.
Show me how I'm reading the picture wrong where it says #6 is the earth to the Coolant lamp W/L????

Inge K. wrote:Coolant temp warning lamp is connected via pin #10.
Switched power in at #6 is correct.

Pin 6. Is absolutely switched power in. It's agreen/black wire I physically traced to the fuse block.

The note on your drawing is wrong. It should say pin6 is power to....not earth to.

Thank you for the correction & I'm truly sorry for posting "mis-information". I hate it when that happens! No I'm wondering where the heck I got that image o start with! couldn't have come from our forum.
Again, Thanks for straightening me out on this (had I looked at my elec. diagram I should have known better!
Thanks to Inge too.
Regards, Ibj...

ibjman wrote:Thank you for the correction & I'm truly sorry for posting "mis-information". I hate it when that happens! No I'm wondering where the heck I got that image o start with! couldn't have come from our forum.
Again, Thanks for straightening me out on this (had I looked at my elec. diagram I should have known better!
Thanks to Inge too.
Regards, Ibj...

No worries. It happens. I think tht drawing was included in the BIG paper written by Bertram on electrical troubleshooting the K1100RS, but I may be worng. Its an excellent resource that paper, and it is somewhere here on the board.

As an aside, I rode the bike to work this morning and the gear indicator works fine for gears 1 thru 3. Gear four shows as an H and gear five shows up as 6. Amusing but harmless, and still very usable.

So far no blown fuse either.

ibjman wrote:Ok....I know better than to doubt Inge.
Show me how I'm reading the picture wrong where it says #6 is the earth to the Coolant lamp W/L????

Don't know where that pic came from but the #5 says Black Neutral light which is also wrong.
There are differences in the pins as models change but that does not fit any model I know of.
I recall a discussion on the Motobrick site some years ago and also the K11OG site.

Try this......I traced these myself.
If you see an error, please tell me what and supply the correct info

Here's a new pic I just finished.....modeled after a 1985 k.
Getting kind of sleepy so you all can critique it to see if it's correct?

I'm not sure about the wire color for pin #8 (used only on early bikes, since I didn't have an 85 wire harness handy to check, but I can check one tomorrow.
Check it out....let me know how it flies???

Pin #8 isn't used on later models, exept ABS models (ABS W/L, green/yellow).

Pin #5, would more correct be: output from GPI PCB.

That is fairly much what I was looking at when I said it wasn't right maybe Neutral start may be more correct but it definately isnt the neutral light itself.

Notation is included to announce pin #8 is 83 - 85 only + re did #5

Changed the wire color on Pin #7 from white to Brown/white

jwetering wrote:

ibjman wrote:Thank you for the correction & I'm truly sorry for posting "mis-information". I hate it when that happens! No I'm wondering where the heck I got that image o start with! couldn't have come from our forum.
Again, Thanks for straightening me out on this (had I looked at my elec. diagram I should have known better!
Thanks to Inge too.
Regards, Ibj...

No worries. It happens. I think tht drawing was included in the BIG paper written by Bertram on electrical troubleshooting the K1100RS, but I may be worng. Its an excellent resource that paper, and it is somewhere here on the board.

As an aside, I rode the bike to work this morning and the gear indicator works fine for gears 1 thru 3. Gear four shows as an H and gear five shows up as 6. Amusing but harmless, and still very usable.

So far no blown fuse either.

I went out for a decent run on my 84 K100RT for the first time since getting her at the weekend. After 6 miles I lost all power to the clocks apart from the Battery warning light. Got to the first brew stop and stopped the bike. Had the brew and went back to start it no power to the clocks and ignition switch. Got the manual out and I changed the 7.5amp fuse and never had a problem for the rest of the ride. I am not sure whether this is a common fault but when I looked under the seat my Brother in Law had a myriad of fuses under there. That's telling me he has had problems at some time. I'll see how it goes as she has been stood for a while. I am going to bookmark your post as I may have to revisit this

Thanks

John

It may help to inspect the old fuse to see if it was "blown", just became defective (IE: element across the center of the view window may have developed a tiny crack), or if by changing it you could have just managed to get the blades of the fuse reconnected with a partially corroded fuse slot connector.

Usually if the fuse is blown you'll see a small burned mark in the plastic window where the fusing wire burned through.

If it was indeed blown, you have an intermittent short (to ground)somewhere in that circuit.....it will occur again if not found & corrected.

Regards, Ibjman

ibjman wrote:It may help to inspect the old fuse to see if it was "blown", just became defective (IE: element across the center of the view window may have developed a tiny crack), or if by changing it you could have just managed to get the blades of the fuse reconnected with a partially corroded fuse slot connector.

Usually if the fuse is blown you'll see a small burned mark in the plastic window where the fusing wire burned through.

If it was indeed blown, you have an intermittent short (to ground)somewhere in that circuit.....it will occur again if not found & corrected.

Regards, Ibjman

 It was indeed blown. I have spares under the seat but as its been stood I am going to see how long this fuse lasts. I'm sure it will blow again but I am going to see how long it lasts before it does. If it blows every time I go out then I will do something about it but if not I can live with changing a fuse every now and again. It only takes a minute to change. Thanks for the advice though

John

I am the culprit posting the original wiring for the cluster instrument.
Thanks to all to correct it. I will post it in the download.

CF

I am having wiring problem with my bike too, I wish I am as talented as you guys to figure out the electrical on our beloved bike. My bike had the overheat light turned on after riding in the rain even though the temp from the thermostat is only above half. I got caught in the rain again this weekend and now my gear indicator is all messed up, the gears are not showing on the neutral light is on every time you change the gear. The bike still runs ok but..... I will try to check the connections on my day off. Thank you guys for sharing your knowledge.

commanderdrako wrote:I got caught in the rain again this weekend and now my gear indicator is all messed up, the gears are not showing on the neutral light is on every time you change the gear. 

The connector to the GPI switch you find under the RHS battery cover.
You will see three yellow wires w/ tracers and a brown wire.

When the different gears is selected, one or more of the yellow wires is connected
to the brown one (ground),
As you got constant neutral, all three of the yellow wires is connected to the brown.

if your lucky it's just a water ingress and short in the connector.