R100GS ELECTRICAL PROBLEM, drained battery

[paulc]

hi
got a problem with my 1991 GS. When I turn on the ignition the battery drains in a few seconds. I know the battery is good and it recovers when the ignition is turned off. obviously difficult to test as I don't want to damage the battery by repeatedly draining it. I am guessing I have a short to earth somewhere but where?. The indicator relay looks a bit suspect with a slightly melted plastic case and if i unplug it there is no drain but nothing works. I cant see how a flasher relay could be the problem so I suspect it could be a red herring. I am a bit stumped, grateful for any advice or hints on where to look for the problem.

[AliBaba]

Are you sure it is the indicator relay?

It's the big black box above the W. Between the regulator (black box wich is red on the top) and the ecu (black box with cooling-fins).



The bike should be able to run normally without the indicator-relay. Everything should work (except the indicators...)

[paulc]

yes it is definately the indicator relay. I would agree with you that everything except the indicators should work without it but they don't which is what puzzles me. It has a lot of connectors for a simple flasher unit so I wonder if it has some other fuction as well. I can't think of what though!

[mark manley]

I think the indicator relay is more sophistocated on this model because of the optional hazard warning lights and left hand right hand on off switching.

[Walkabout]

Originally Posted by paulc

hi
got a problem with my 1991 GS. When I turn on the ignition the battery drains in a few seconds. I know the battery is good and it recovers when the ignition is turned off. obviously difficult to test as I don't want to damage the battery by repeatedly draining it. I am guessing I have a short to earth somewhere but where?. The indicator relay looks a bit suspect with a slightly melted plastic case and if i unplug it there is no drain but nothing works. I cant see how a flasher relay could be the problem so I suspect it could be a red herring. I am a bit stumped, grateful for any advice or hints on where to look for the problem.

Interesting.
Are you describing things accurately in your post?
What I mean is:-
Do you really have a good battery? No indicator circuit should drain your battery, not for many hours anyway. Just switching on the ignition circuit should not drain the battery. I guess you realise this, so do you have more than one electrical fault which are leading to strange symptoms?

When pulling the indicator relay, are you disturbing some other electrical connection?

Just my thoughts, based on your information.

[Magnon]

The indicator relay may be a red herring but if the bike does have hazard lights these should work with the ignition off. If they are still working correctly and the indicator relay ticks away and you still have a problem with the short when you turn the ignition on I would look at the hazard switch and associated wiring. Does the parking/side light work?

[McCrankpin]

Hope this helps.....

The significant thing for me is that the battery drains in a few seconds.
For a good battery to drain in a few seconds, that's a LOT of current flowing and you'd expect something to burn out and melt with a bit of smoke, or a fuse to blow.

And normally, a drained battery won't recover just by turning the ignition off, specially one drained so quickly.
So are you really certain the battery is good?

Also to help to understand things - What is it that tells you the battery drains in a few seconds?
And what happens that tells you the battery recovers when the ignition is turned off?

Hopefully these answers will help to find the cause of this.

[paulc]

Just to say thanks. For those who are interested the indicator relay was indeed a red herring. With a healthy 12.75v across the battery and a complete discharge of the battery when anything was switched on I was suspecting a dead short to earth so I was looking for something with scorch marks on it and the battered looking relay looked a likely culprit. I didn't suspect the battery but after reading these posts i decided to eliminate the possibility by connecting up a spare battery from my other bike. To my surprise everything works fine!!

In 30 years of riding I have never had a battery fail suddenly without warning in this way and still show a voltage. It's easy to convince yourself you have got one type of problem and it sometimes takes someone else to state the obvious.

Still don't understand how the indicator relay makes a difference to the rate of discharge though, I can only guess that by disconnecting the relay i was taking a little bit of load off the battery making discharge a little slower. You live and learn!!