I've had a search around and can't find anything referring to what i'm trying to achieve, essentially there is a K-BUS network (single wire) between the FFBH, IPK and climate control. I've extended this to pin 7 of the OBDII connector, using a USB-KKL adapter, previously working fine with W-BUS on the same pin.
I've had no luck getting the FFBH to respond to the Thermotest software using the correct TTC/Z BMW comms configuration option, I can connect to the FFBH using Autologic, which uses the IPK as the gateway, but this approach is limited.

I've tried with ignition on & off, no difference, there is K-BUS voltage at pin 7 on the adaptor, I've not 'scoped it yet to check the frames but as it's communicating with the IPK, I'm making the assumption that the data is usable.
Short of connecting to the leg going directly to the FFBH and putting a changeover switch in to isolate from the rest of the bus, I can't see why it's not working.

Has anyone else tried this?
Did you get it to connect?
Thanks.

All that is way above my pay grade but I do know the Gap Diagnostics IID tool solves your problems, others have tried various different approaches but few have succeeded.

Good luck, I hope someone comes along who can help but don't hold your breath...!! Pete
I now have permission from the boss to use Y.O.L.O. Enjoy life
__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand Sold
2002 L322 Vogue 4.4 V8 Epson Green (Fatty Offroader) Sold
-Click for Project Fatty off roader-

Thanks, I don't think that the Gap tool does any more or less than the Autologic I already have in terms of FFBH functions. It's not really a 'problem' as such, more of an annoyance - something that should work, doesn't... I suspect it's to do with Bus ID numbers, the IPK being the gateway will always be ID0, maybe this is somehow blocking the KKL interface as it won't know how to redirect traffic...
I'm going to remove the FFBH to refurb soon, I'll put a bypass on the coolant lines so I can properly clean the combustion chamber & heat exchanger in slow time, if I have no luck finding a solution by then, I'll run a separate line in to the OBDII with an isolation switch to disconnect the IPK & climate control. It's a bit of extra work but should be useful for future diagnostics / pre-winter test runs etc.

ETA - apologies for the rough sketch, here's the workaround, I can fit a low profile rocker switch next to the OBDII port which should be both easily accessible and not prone to inadvertent activation. K-BUS is a relatively slow voltage pulse based protocol so a switch shouldn't cause any transmission issues.

I don't know if the Gap tool does more or less than the one you have, apparently it can do more than the JLR tool... I think it's success is that they have sorted out the connectivity and it is just plug and play.

With your knowledge and experience to work around the problem you'll have it sorted a lot cheaper...

Having said that the IID tool is worth £350 minimum second hand so the overall cost of ownership is competitive Pete
I now have permission from the boss to use Y.O.L.O. Enjoy life
__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand Sold
2002 L322 Vogue 4.4 V8 Epson Green (Fatty Offroader) Sold
-Click for Project Fatty off roader-

have you read through the info in the Disco4 forum https://www.disco4.com/wiki/Webasto_Thermo_Test_Setup
I started but ran out of enthusiasm after finding the circuit board in the heater burnt out under some to22 packages (which I think are diodes)
A common fault is the gunk used to hold down the capacitors east some of the smt resistors, which I had to change on the secondhand one I bought to replace the burnt out one.

Ian Do I really have time to tinker with one of these

Thanks, Yes - I'm aware of that potential issue, I don't think it's applicable as I have reliable comms to the FFBH with my Autologic unit which uses the IPK as a gateway (as will all diagnostics through the OBDII socket, regardless of whether it's SDD or aftermarket - that's just how it is set up). As far as I remember, the issue with the 'resistor rot' is ghost errors relating to the fan, burner or water pump, the comms area of the PCB is in a different part to that affected by the adhesive.

I have Thermo Test set up on a couple of devices and have connected to W-BUS and K-BUS heaters out of the vehicle so I know the KKL adapter and the configuration of my devices is correct.

Well I removed the FFBH today, connected a 25mm hose elbow in it's place as I planned to refurb it in slow time - needn't have bothered! I took the burner out (which had a hard fault for the glow pin) and it looks barely used, so I cleaned it up in the parts washer with a blast of brake cleaner to get rid of any oily residue, stuck in a new burner & glow pin assembly from Webastoo Parts, which came complete with new gaskets, bolts, etc. for a reasonable £80 inc postage, re-assembled, refitted, bled the coolant through and fired it up (ambient was 14deg. C. so just in the window!), at first I didn't think it was working as there was no smoke, it ran for 30 mins with no drama's and shut down gracefully, refitted the wheel arch liner and ticked another job off the list - oh, connected to K-BUS fine with the KKL adaptor once the IPK & climate control was isolated so I think I'm going to find the SJ or somewhere FFBH-side of it and run a twisted pair to a switch, as the sketch above.

I also took the opportunity to remove the adhesive on the control PCB, came off easily enough, the tropicalisation of the PCB leaves a lot to be desired, I can't help thinking that if they applied the adhesive over the top of the varnish, there wouldn't have been an issue.... Anyway, I use the technicians go-to when the correct alternative isn't available - 'black sealer' to hold the caps in place, I applied it where there were no SMT components so there shouldn't be any issues.

New burner & service kit

Click image to enlarge

Click image to enlarge