Help, Lost almost all electrical 1995 R100gsPD

With the light switch on the rhs switch cluster. Has off,park,on options.

Park option in my 95gspd is a position on the ignition switch, and the controls for the head light on my bike islimited to hi, low, momentary high.

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Thanks for the diagram, yes yellow is starter relay, the rear black relay seems to controll lighting, turn signals and horn. (possibly more) While the forward black relay must be what you call the load shedder. What exactly does a load shedder do?

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Ah ok, maybe its a legal thing as newer bikes over here have no option to turn lights off while riding. Anyway, we seem to have the same problem, another thing mine does when it loses its electrics is flash the gen light when say the horn button is pushed or the indicators used. I still wonder why the relay is affected, and eventually destroyed.

When you try to use the starter motor lots and lots of energy goes from the battery to the starter motor. The battery is very stressed by this load, so to avoid placing yet more load on it some bikes use a relay to remove extra loads, like lights, from the battery while the starter motor is in use.

There are various legal requirements around the world .. in some parts headlights must be on all the time. Most European countries allow their riders to think for themselves. I am surprised that New Zealand has taken a different path ... or possibly it is a cost thing - less switches = less cost. A polly in Australia thought it was a good idea and introduced it there .. after some years the stats said it made no flaming difference and that stupidity was undone. His name is Brown and he lived in the Hunter region of NSW. Australia most of the time has bright sunlight ... highest rate of skin cancer in the world .. a skin cancer caused by sunlight! Brown would not listen to common sense.

Sorry for off topic, but I may be wrong about NZs law about no off switch, but it is a requirement to ride with lights on. Anyway, have you got any theories about mine and the ops relay issues? Just seems weird that mine just seem to eventually stop working after a while. Maybe the ops will do the same if he replaces them?

a few theories. poor contacts on relay and or receptacle? perhaps vibrations cause wear? (because a wiggling of the relay seems to remedy)

could it be possiblilty is that is is actually the load shedder relay that is bad? I mean could it engage out of the blue? and cause the symptoms of lost electrical lights, horn, signals etc....


I am not sure how relays fail, i know they can get sticky, but can they be activated when they are not supposed to, or deactivate when they are supposed to be activated. I wonder if either of those scenarios is even possible?

Replace the relay and see if the fault goes away ... relays being cheap, easy to replace and require little knowledge or fault finding skills.

Some of these load shedding systems rely on the starter motor resistance ... if the starter motor brushes get dirty that can cause problems..1988 to 1990 GSes being one system that suffers.

If you want to take out both the load shedding relay and starter motor as causes then .. remove the load shedding relay and jumper from pin 30 to pin 87 on the now vacant load shedding relay socket - your lights will now be on all the time, key out included. If any thing fails with this configuration then it is not the load shedding relay nor starter motor causing problems.

The fault is intermittent. When it does occur it seems it can be remedied by wiggling, tapping, or nudging the turn signal relay.

It would be easier if it was persistent.

I do appreciate all the suggestions, I may yet get a chance to jump the starter relay socket as you suggested.

The Load shedding relay!

The starter relay will make the starter motor operate ... if you jumper it then the starter motor will operate continuously .. even if the engine is running..

I'll add some more words to my post above so it is obvious what I am talking about?

thanks, it is very clear now, i am sure however I would have taken pause when not finding the pin numbers on the starter relay

Those pin numbers ... at least one if not both will be on the starter relay ... and many other relays if they follow the DIN standard for numbering there pins. The pin number describes what it is inside the relay.

If it goes away when you tap, wiggle the relay then it must be either the wires, connections or the relay.
Can you borrow a relay from somebody as a test? Else, just buy a new one. Piece of mind. I have had one in the past that was suspect
And check connectors are clean and tight.

babaji You have a PM, feel free to share around.

Provided that is all that is done.
If you restart the engine, the starter motor turns over. If the tapping is vigorous enough then the starter motor may well feel it. All too easy to assess the problem based on text ... but what happens in reality? Have to read between the lines and I, for one, am not good at it.

If we are talking about the micro relays you can just barrow one from your car
dont worry about the 87a terminal is it just not used in this ap and wont hurt any thing
But of course the starter relay is very special and is not a standard mini relay

well i have swapped, the light relay with the other one identical black relay (load shedder) or at least i hope i did, i had them both out at the same time and now have lost track, of which was which duh!)

If it recurs i will swap them one more time, after that, I will open the wallet and buy one or two of those relays. i will also be watching to see that the headlight shuts off (ie load is shed) when starting from now on. To see if I have just moved a bad relay from the lights to the load shedder. If it continues beyond that, I will investigate female terminals to see if they can be tightened / cleaned etc.

off topic, I hardwired my two 55 watt halogen fogs into my Eastern Beaver PC-8 fuse block, they are on a switched circuit, so they turn on with the key. Made sense to me at the time, weather was warm bike started well all the time. Well i got up one morning after it hit freezing cold overnight and had a real real hard time starting the cold bike with those lights one. I have ordered a switch, for my handlebars to control them from now on. On the plus side, i get to add another relay for that switch! Yay!

good to know, could be useful in a pinch

a also wondered about tapping the light relay, if that force was also being transmitted to the load shedder relay, will take care next time

Given that I cannot find a 'light relay' on a few BMW airhead wiring diagrams .. and I don't know what bike you have ... and I see you have non BMW accessories fitted .. then I cannot work out what your talking about. Good luck.

{edit} earlier diagrams have a 'light relay' .. same function as the 'load shedding relay'... that is where this confusion come from!!!

So ... what bike are you working on .. model + year. Then 'we' might get to the same ruddy page.

I do prefer the term 'load shedding relay' .. light relay not so much.