G'Day guys, I'm hoping you can help me.
I've been working on a 1997 model K100 with a friend. He wanted to pretty the old girl up so we took off all the fairings and painted various bits, disturbing the wiring as little as possible.

It's all back together again now but when I hook up the main connector to the Motronics unit, all the electrics turn on - even when the ignition's turned off...!

We're going kinda crazy here trying to figure out what it is that we've done wrong, as everything looks as it should.

Any clues please?

Thank you
Mark Franks
Cairns, Australia

Does the engine turn over as well and if so it's the starter relay which gets its earth through the Motrinic ECU.

Hi Rick,
yes the engine turns over fine. It doesn't fire and I'm getting petrol in the exhaust. Something is very obviously wrong, but I can't figure out why connecting the Motronics unit would cause the ignition to turn on, even when it's fully turned off - the key's not even in!

I was thinking of the engine turning all the time but apparently not.
Have a look at the ign key switch or possibly in the right handlebar switch. If either has fallen apart then a short that turns the ign on is very likely.
There is a heap of info available here but you need 3 posts to access it, done that way to prevent bots getting at it.
Do you have an electrical circuit diagram for the bike as that will help.
You said a 97 K100 which cant be right as K100 finished in 92.
It has Motronic so it must be a 16 valve engine and if a K100 then 88-92.
The vin and engine NO will help or if the ID plate is on it that will tell you.

sorry, it's actually a K1100. An ex NSW police bike.

Here's the full scenario;

Turn on the ignition with the key and the electrical system activates normally i.e dash lights, headlamp, neutral indicator etc and the engine turns over on the starter button but does not fire up.

Turn the ignition off and the system shuts down

BUT if I connect the Motronics unit, the electrical system activates even when the ignition is fully turned OFF.

It's as if connecting the Motronics unit bypasses the ignition circuit somehow.

I've clearly either done something wrong connecting up the wiring (which I doubt, because all the connectors seem to be the 'plug and play' type that can only connect one way) or there's something simple that I've overlooked...?

Or maybe the Motronics unit has chosen this week to implode for no apparent reason???

Thanks again for your help.

The only plugs you can connect wrong and they are under the right side cover the fuel tank 4 pin and the ABS rear wheel sensor 4 pin. I cant remember what it was they do but on the K100 was really strange. Worth a look.

Welcome mfranks
those of us who own ex police bikes have found that when being decommissioned, the wiring for sirens, flashers etc is just chopped off and sometimes just taped together in a real jumble. Go to your R H switchgear and try to follow all the wires back under the tank and seat, they may have some earthing or shorting happening.
Good luck
RT

Thanks, I'll take another look at the wiring. It was all working perfectly before.... I was hoping that it might be a 'known' problem amongst Beemer Boys, but with luck it's just something simple!

Mark