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[Rattlebattle]

Not had a good morning. First off the metal speedo drive I bought to replace the plastic one doesn't work; too much slop in the drive square methinks. Much worse is that the engine runs very poorly above tickover, to the extent that I just about managed to get home. Plugged a wire into the MIL diagnostic socket and grounded it. Lo and behold I get 6 short and 6 long flashes. Would appear therefore to be the crankshaft position sensor. Great. Dealer closed today so not a lot I can do. Symptoms are similar to those on my oilhead BMW when the Hall effect sensor went bad ie will start ok but pop and bang when the throttle is opened. I suppose it could be a connector not making proper contact. We'll see. Not even run in yet....

[jefrs]

Have you tried cutting power to the ECU to effect a reset? The ECU is practically 'always-on'. In theory throwing the kill switch should do it but not sure it does. Pulling the ECU Fuse is a sure way of disconnecting it, simpler than pulling the battery.



The ECU can be reset and will recover from faults, been there; if you over-rev it (hit wrong gear when cut up on rdb) it will go into a similar fault state: it cut out and would not restart, I switched off, kill switch, waited and restarted all back to normal. Off for "20 seconds" min (go make a cuppa).



Yes do check for dodgy connectors because it does have dodgy connectors, especially check the chocolate box on the crank sensor in the frame 'hole' because the wiring loom is a bit short and tight.



Best of luck, Jeff.

[papasmurf]

BMW electrical connectors are in my experience the source of most electrical problems. I have now learned at any sign of electrical problems to clean all related connectors before I even think about it being a component failure.
Usually cleaning a connector(s) works.

[jefrs]

Rule 1 - don't look for complicated, look for simple, stuff that moves, what happened just before it assumed rotund pearosity. The sensor is well protected, the wiring is a known problem area.

[Rattlebattle]

Thanks. I'll see what disconnecting ECU does and check the wiring. BMW HES failure is a known problem. As they age the wiring gets brittle and crumbles causing rogue signals. Replaced two in my time, both successfully, but sensor on RE should be ok at three months....

[Scalyback]

ECU reset - clear logs and things.



I don't Have Thunderbolt to check on anymore, but apparently, the RE ECU can be reset if it has made a hash of things.





ECU RESET:



Check for all the sensor connections plugged in properly and then reset the system by the following procedure.


Switch on both the ignition key and kill switch wait, for 10 sec then completely open the throttle for 10 sec, then release the throttle, after 5 sec mil will blink continuously twice, reset completes.

Then switch off the ignition and switch the ignition key on again. wait for 3 sec then start the engine.

(note during reset procedure the engine should not be running, only the ign. Key and kill switch is to be turned on.)

[Rattlebattle]

Thanks Scalyback. I tried that but I guess it only works when a fault is no longer present. When I leave the ignition and kill switch on the MIL comes on, which is what happened before ie switch ignition and kill switch on MIL is on as normal, then goes out. After maybe 5 seconds MIL comes back on and stays on. Engine will start but runs very badly except that it will tick over. Earthing the ECU diagnostic plug gives 6 short and 6 long flashes. This is the opposite of what the manual says but crank sensor fault is the only one with 6 of each. I have tried pulling the ECU fuse and waiting. This has had no effect. I've tried checking the plugs as best I can but found nothing obvious. Some blame a poor negative battery terminal for a lot of ills but as far as I can see it's ok. Must either be wiring or bad sensor. Warranty job methinks but I had hoped I could fix it.

[Rattlebattle]

BTW I did disconnect the side stand switch because I prefer to leave it running on the side stand to warm up. It has run ok like this. I can't see that the two things are connected but maybe they are?

[jefrs]

The sidestand only breaks the ground connection to the starter relay (without which it won't turn the starter), it's not connected to the ecu, this is not the problem.

The battery connectors are flimsy and there are two wires on one terminal if not both, this could cause a poor ground. Double-check the black lead connections and the in-line connector on the thinner black wire from there. Level 2 Test Pin Long 6 Short 6 and Level 3 DOL P0335 are Crankshaft position circuit malfunction = "Crank sensor loose connections faulty" = "Check crank sensor and connections" (workshop manual). Which I guess is best done as a warranty job, it looks like the rhs crankcase has to come off.

[Rattlebattle]

My thoughts exactly on the sidestand, which is why I thought it straightforward to disconnect. I have proved that this is how it works anyway by connecting the two pins in the wiring loom socket with a bit of wire and then checking that the fuel pump doesn't prime etc. I agree therefore that it won't be the sidestand switch. I have a feeling it's the wiring. I did try connecting a separate main earth from the battery to ground, but no dice. I know that the negative terminal/leads especially are prone to internal breakages etc.As far as I can tell the thinner black ECU ground wire from the negative terminal is ok. I did wire in an Optimate lead to allow me to charge the battery in situ. I do therefore wonder if, although tight, there is a wiring fault somewhere. Yes, I know what the 6 + 6 means; I do hope it's not the sensor. Either way, it's time to test the warranty. I'll report back if it gets sorted. Might help others with the same symptoms. Oh, a final thought: I did remove and check the spark plug, an Iridium one I put in from virtually new. I suppose it could be a loose connection there or at the coil, but I would have though the fault codes would have been different. Who knows? Thanks for your help.