Haynes manual doesnt include twin plug??

My haynes manual which ive just bought doesn't include a wiring diagran for the twin spark ebgine, only the single spark. What gives!? Im trying to test the wiring for the stick coils as they arent recieving a signal or have lost power (the stick coils are brand new because I thought they were at fault) but the haynes manual doesnt have a diagram, only one for the single coil/plug wiring harness??

Or have I missed the obvious! !?

What makes you think that the stick coils are not getting power?

What are your symptoms?

The green wire on pin 3 has power from the ignition switch.
The black/tracer on pin 1 is the signal from the motronic.
The brown wire on pin 2 is earth.

Your bike should run on the secondary plugs, but obviously rougher then normal. So if your bike is not running. I would suggest something else is wrong.

There are wiring diagrams available for the twin spark, but as far as I am aware, they are only available from BMW. The wiring diagrams off the net are for pre twin spark.

Ian

The bikes running but only on the secondary plugs, the stick coils arent firing the plugs on either side, tested with a spare spark plug earthed out of engine. Of the stick coil plug wiring I can find an earth (the short wire onto the head) and continuity from a one pin on each stick coil to a single pin on the ecu plug connector. But nothing on the other pin. Maybe that's the 12v ignition feed? None of the three stick coil plug connectors have power when the ignition is on or even cranking. Any idea?

Ok it sounds like you have lost the 12v feed which comes off the ignition switch.

The trouble is this same 12v also feeds to the secondary ignition coil and other services as well.

The wiring diagram shows it as going thus:-

Ignition switch to crimp connector X9450 (12v)
X9450 to secondary coil
X9450 to left stick coil
X9450 to right stick coil
X9450 to fuse 1
X9450 to horn relay
X9450 to load relief relay
X9450 to right combination switch (kill switch)
X9450 to abs warning relay.
X9450 to abs control unit.

So there are a lot of wires crimped together at X9450. It might be that corrosion has got to that crimp connector and has unusually attacked just the two stick coil wires. But I'm not convinced of that.

It is unusual for the power to be lost to both stick coils. It might be worth your while tracing the wiring back from the stick coil connectors to see where it goes. You will be tracing the path of the green wire.

I suspect that the secondary coil 12v from X9450 has a another crimp connector with the two 12v for the stick coils. Though I might be wrong. Either way following the wiring back from the stick coils will help.

The crimp connector X9450 is located along with most of the other crimps on the left hand side of the frame near the alternator. There is a black stub about 6 inches long and about 1 inch diameter which is folded back onto the loom. Once the tape is unravelled you will find all the crimps. You will be looking for the green wire crimp which should have about 11 wires of varying thickness all crimped into one big crimp. But I would leave this alone unless you are convinced the break is nowhere else.

Good luck

Ian

I should add that working back from the stick coil is the most logical way to go.

You can use a dress makers pin to push through the wire insulation and check for the correct voltage long the length of a piece of wire. This helps to try and find a break point without the need to strip or cut the wire.

Once the pin is removed, the insulation will move back to close the hole created by the pin. So the risk of corrosion is minimal.

Be careful with the green wire, as it is unprotected and if you short out your pin, you may well melt the wiring loom

Proceed with caution

Ian

Morning, thanks for the lengthly reply! Fixed the problem last night! ! It was the load relief relay, the coil windings inside had cone away from the terminal, 5mins with a soldering iron and its got 12v back to the stick coil plug and its firing the plug beautifuly

Lesson learned.