[suffolk boy]

Originally Posted by BigRuss

When the heater has been running it will still operate after the ignition is turned off this is normal as it goes through a shutdown proceedure where ignition is cut, the internal fan then continues to cool down the burner, when cool enough the FBH will shutdown completely.

Please don't go cutting the K-bus wire with no good reason, if weird stuff is happening to other electric systems then unplug the FBH, your PCB is faulty.

There for a very good reason for the K-bus, it's there for diagnostic purposes, the cars ZCS coding includes the heater, when on T4 and running a diagnostic it will look for the heater via the K-bus if this is cut then it doesn't find it and you won't be able to run a full vehicle diagnostic.
Makes the time diagnosing faults an awful lot longer because then each ECU then needs to be accessed seperately. (the same goes for anything connected to the K-bus, CAN-bus or Nav-bus.)

Russ

looks like i have a little job to do on monday then