Solved! Webasto FBH Diags

[Keith]

A bit of info on the Freelander FBH I bought.

The firmware on the unit reports itself as 'Rover' not 'BMW' as is the norm which I found rather interesting as I had never come across one with Rover firmware till now.

The unit requires +12v on pin three to makes it work as a parking heater. The earlier 75 units also worked like this but later models switched to grounding pin 3, I would be interested to see what some of the last 75s produced require, perhaps it varies a lot more than originally thought!

The firmware on the unit properly triggers the relay for the cars heater blower fan only when it is up to temperature i.e pin 4 on the FBH goes to 12v only once the FBH has got up to about 30 degrees, the firmware in the standard Rover FBH (in my car at least) switches pin 4 on immediately which I always thought was probably not what was intended!

One advantage to that is faster engine warm up (FBH primary function) and less drain on the battery as the heater blower is only switched on when there is enough heat in the water to make it worthwhile

The Freelander FBH also operates in a summer cooling mode i.e grounding pin 5 stops the FBH firing but instead just operates the output on pin 4 to allow the car to be ventilated.
I have not checked to see if my own FBH in my car does this as well but as my Telestarts support this as an option I will have to look into it in the coming weeks

Also the diags properly show the correct water temp unlike the bonkers readings above from the 2001 model in my car

Why the above waffle?
Simple if you need a new PCB for your FBH the Freelander one looks like it is worth considering rather than one from a BMW unit

[Gryphon]

[QUOTE=Keith;123085]Gents I recently bought a job lot, a T100HTM Telestart which came with a brand new (but faulty) FBH a fuel pump and full wiring loom etc. I was really only after the Telestart to upgrade my T80QUOTE]


Keith does this mean you have your old remote start for sale? if so i would be interested in buying it off you.

Regards

Garry

[Jules]

Keith, great work so far!
As we are now proud owners of a Remote FBH and a Tourer to go with it!!!
Would it be possible for you to stop the in car fan coming on straight away and in fact make it a summer venting system too?

Also quick question,
If the Remote is used to turn FBH on, I have not found a way of turning it off manually yet, from the timer key pad (say if Mrs Jules went off to work without the remote, we only have one)

[Keith]

Originally Posted by julesbass

Keith, great work so far!
As we are now proud owners of a Remote FBH and a Tourer to go with it!!!
Would it be possible for you to stop the in car fan coming on straight away and in fact make it a summer venting system too?

Also quick question,
If the Remote is used to turn FBH on, I have not found a way of turning it off manually yet, from the timer key pad (say if Mrs Jules went off to work without the remote, we only have one)

THe standard BMW firmware on our version of the FBH does not seem to use the onboard temp sensor or perhaps it does but as it is designed to turn on the heater fan at 30 degrees and on the basis mine says stupid temperatures when the burner is running (several thousand degrees) I think the firmware is just wrong or my FBH is doing odd things

So all I can suggest you can do is stick a thermostatic switch somewhere on the FBH body and put that in seiries with the wire from pin 4 of the FBH.

My Timer works fine with or without Telestart but obviously it does not know the telestart has turned the heater on so I just firstly have to turn the heater on and then off with the timer

Summer winter is available via earthing pin 5 on the FBH either with a switch or is the telestart is wired up and supports it via a combination of buttons on the remote

If you look at the Telestart receiver see if it has a purple wire in pin 5 that goes to pin 5 on the FBH and provides summer winter control of the FBH

A Telestart is wired:

1, red +12v
2, yellow input from interior temp sensor (T100 HTM only)
3, black output +12v parking heater on signal
4, grey input from timer
5, purple output summer winter control
6, brown ground

[Keith]

Today I got my hands on one of the earlier FBH variants to repair for a member.

A model 66232C, as stated in my Howto these are wired slightly differently
what I had not be able to check until today is what else is different

This model has pin 3 wired to the ambient temp sensor so that the FBH will act as an auxiliary heater, the later model 98570B uses pin 1.

The 66232C uses pin 1 as the parking heater control, the later model (98570B) uses pin 3

So effectively the function of the two pins is reversed

There is one other major difference the 66232C requires +12v on either pin to operate it, the 98570B uses a grounded connection to pin 3 for the parking heater function.

The firmware on the 66232C is actually better than on the 98570B as it correctly powers up the ATC panel control relay only once the FBH is up to temperature unlike the 98570B (well mine anyway) which turns on the ATC relay immeadiately. I also noticed it only operates the ATC relay in parking heater mode not auxiliary heating mode.

What does this mean to an owner?

Basically if you replace a pcb from a 98570B with one from a 66232C (as they are perfectly interchangeable) and you have a timer or Telestart fitted you need to do some alterations

Firstly the wires to pin 1 and 3 need to be swapped over secondly the relay from the Telestart if fitted needs to be modified or bypassed (by simply using the direct +12V output from the Telestart or timer) so that +12v is applied to pin 1

cross posted to my Howto

[pondweed]

Originally Posted by Keith

*The 66232C uses pin 1 as the parking heater control, the later model (98570B) uses pin 3
**The firmware on the 66232C is actually better than on the 98570B [/I]

*Actually the official Webasto 75 CDT parking heater kit still recommended using pin 1 for power up using a spliced, diode-protected feed! We have all just conveniently found that pin 3 earthing seems to work...

** you also get a summer cooling function which cant be operated on the later K-BUS units.

There is coverage of this in the pdf.

[Keith]

Not quite Jon

There is a difference depending on which pins are used to operate the unit, nothing happens on pin 4 if power is only applied to the relevant "auxhillary" heating input i.e pin 3 on the 66232C.

I need to check if that also applies to the pins on the 98570B as that may help people if they get into a situation of swapping one type of board for another.

[sigor]

Hi,
I have one pdf in German about upgrade kit from Webasto. Is this good kit?
Are PCB's for our Webasto heaters available (for 66232C or 98570B)?
Thanks to Keith for all information.

[Keith]

Yes I have that doc as well thanks

The PCBs (either type) are only available new as part of a complete heat exchanger unit afaik, according to the Webasto parts list. And at a ridiculous price although I am going to investigate that in a bit more detail one day.

I have not found anywhere that offers component level repairs
I suspect some of the odd K bus behaviour we experience on these may be corrupted firmware so it would be nice to find out if the boards can be reflashed

Cheapest way is to get a pcb is from a breakers as there are plenty of identical units in BMWs etc, but you are taking a risk as you can not easily test them.

[pondweed]

Originally Posted by Keith

Not quite Jon

There is a difference depending on which pins are used to operate the unit, nothing happens on pin 4 if power is only applied to the relevant "auxhillary" heating input i.e pin 3 on the 66232C.

I need to check if that also applies to the pins on the 98570B as that may help people if they get into a situation of swapping one type of board for another.

Keith -this is ambiguous! but then perhaps my statements were too...! So:

Webasto originally intended 98570 to be powered up for parking heater control by pin 1 too.

Summer cooling function exists only on the 66232 and, of course, this only functions when parking heater function would be activated, in this case to cool the interior.