Hi,

I am new here but have searched this site for solution but in vain.
My 2002 (03MY) HSE has optional FBH. It's RR original from the same manufacturing date as car. Now the things i have done so far:

1. Got myself Reslers I/K-bus adapter. (works like a charm)
2. Checked the webasto with WTT. (via k-bus from my absent rain sensor connection)
3. Checked the auxiliary coolant pump (worn but works)
4. Checked the HEVAC ECU output to coolant pump. (does engage when engine running)

Trouble is that webasto starts OK. But as HEVAC ECU does not start the auxiliary coolant pump the temperature skyrockets quickly and webasto shuts down. This condition happens if i start webasto from MID menu with car not running.

If I start the engine and THEN webasto the auxiliary coolant pump runs and webasto works fine.
At first i thought maybe HEVAC ECU does not communicate on K-bus but when i look at navcoder log i see that when i turn on or off AC it tells about it on the k-bus.

Has anyone any ideas what to check?

is the AUX water pump you mention the one that is part of the FBH or the one fixed to the inner wing

http://www.the75andztclub.co.uk/forum/showthread.php?t=100297

the above link will help you check and test the outputs to the waterpump

Hi,

thanx for replay. Of course i meant the pump mounted on engine bay. Feel a bit stupid right now, totally forgot that FBH has pump of its own.