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9 Posts
Discussion Starter #1
Hi Guys,

L322 Diesel (Ford)( V8 fitted with OE Remote Control FBH.
The cabin fails to get warm when the FBH is manually set using the remote.

The Remote manual signal is received and initiates activity within the vehicle (cabin air movement fans I guess) but the heater fails to ignite and consequently fails to warm the interior. In addition one or two warning lights on the ATC start flashing. The main dealer has had the car in more than once and and are now talking about changing the ATC!

Maybe there is somebody on the forum who could assist me with answers to some basic facts about the Webasto system as fitted to Range Rover. I understand that there are differences between the L322 installation and that fitted to X5.

Since the FBH is digitally controlled via its own WBUS, and interfaces with the vehicle CAN through a "black box" I assume that the FBH diagnostics (I have a list of Webasto Fault Codes) are available through the RR Vehicle CAN diagnostics port. Is this a valid assumption since the dealer has not advised that a fault code has been set? I also understand that the FBH has a lock out function (a bit like your combi boiler at home) and I have picked up the suggestion from a Rover 75 site that if the unit goes into this mode that it is not simply a matter of pressing a "Clear" codes button in the diagnostics software to clear the issue. If indeed Webasto Codes can be viewed via the standard LR diagnostics package I would also expect there to be a flash memory capturing the conditions that caused the lock out.

I understand the principles of CAN communication but do not have specific knowledge of what can be accessed, how and whether "special" software is required to access the Webasto codes.

I have also picked up that the system checks amongst other parameters voltage (both High and Low) in addition to ambient & engine temperature as well as low fuel etc etc, and presumably the digital data for this is supplied via existing range Rover sensors rather than specific Webasto ones.

Any help would be appreciated and please don't be concerned that any reply needs to be understandable by a lay person. It's the detail of the system that I'm missing, not the concept.

Any assistance would be appreciated so that I can understand the system and therefore assist the dealer in trying to resolve this long standing issue. I suspect that they do not understand the electronics but are rather relying on LR diagnostics and replacement boxes...the usual story.

Looking forward to your replies!


2002-2005 Range Rover MkIII / L322
23 Posts
i retro fitted a webasto to my 2003 petrol vogue a few years ago and found the 75 and zt owners club forums invaluble
below is the first few steps in the diagnostics ,dont cut any corners ( like for any electrical problem )
is the park heater and / or cold climate enabled ?
IT IS THE SAME AS THE X5 it uses the same canbus / wbus and will be dead when its not connected to the car

this is from the 75 and zf owners club ( french mike is the guru on webastos )


-Engine cold and stopped

-At first, unplug then replug the power connector (or fuse F59 20A )for 30 seconds in order to reset the system.

Simultaneously start a TIMER/STOP WATCH and press the remote and listen when the fan stops( not in the car the webasto fan)

IF stop after 3 sec, restart 4 seconds later and finally stop at 2 minutes 7 sec;
An error is generated; may be caused by:

-Battery voltage lower than 10 volts
-Glow plug open or short circuit
-Circulation pump open or short circuit
-Fuel pomp open
-PCB defective

IF stop after more than 2 minutes 10 sec, then
PCB and all devices are good (except doubtful glow plug)

IF stop at 4 minutes 5 sec, Glow plug resistor too high (0,6 ohms for instance),

IF stop at 4 minutes 40 sec it is a ignition fault, (fuel pump priming fault e.g.)

READ RAVE AND LOOK AT THIS THREAD = http://www.the75andztclub.co.uk/forum/showthread.php?t=100297&highlight=fbh+service

ALSO VERY GOOD READING = http://www.disco3.co.uk/gallery/albums/userpics/11505/Installing a Fuel Burning HeaterTimer Remote v1-1.pdf

hawkeye diagnostic tool will show up faults and enable to test glow plug/fan/fuel pump/water pump ect, also many other faults on car ( best £250 ive ever spent)

best of luck nige

9 Posts
Discussion Starter #3
Hi Nige,
Thanks for the response but unfortunately your reply does not resolve my issue. Maybe french mike is the man unless you can provide further system info.
JFYI LR themselves are struggling with this and have been changing units left, right and centre, which is why I've started to investigate. They must have missed something. This installation was supplied as an OE option.
The heater has worked during my ownership of the vehicle but it became intermittent and has stopped working via any of the 3 customer start routines. 1. Remote. 2. Touch Screen Manual and 3. Touch Screen Timer.
No codes are set in either the ATC or FFBH ECU's (the FFBH ECU being visible via the car OBD).
The vehicle coding has been double checked...Diesel TDV8 not Petrol
However. it should be noted that the FFBH fires up with no trouble when "activated" via diagnostics.
So what is the difference when commanded this way. I make the assumption that the +ve power source (start command) is different plus the operation ECU is overridden.
Referring to the control block diagram the only thing that would appear to fit with these symptoms would be a Logic condition not being met.
The FFBH and ATC ECU's and Battery have been changed (under Warranty) and all connections checked for corrosion etc. so the possiblity of a CanBus transmitter/Receiver issue is very unlikely especially when the Remote signal is received and operates the ATC in ventilation (cold) mode.
What I have discovered is that the vehicle has more than one voltage management system onboard. The vehicle controls Hi / Low voltage for critical circuits e.g. ABS, EPS. Cruise etc. (for safety reasons) in addition to ensuring that sufficient power is available for engine start but I believe the FFBH also has a similar management system of its own, albeit with wider limits, than the main vehicle system.
What I do not know is whether the +ve supply for the different user command routines are vehicle voltage managed or not. Open circuit battery voltage after overnight soak is circa 12.3 volts on a cold morning. The FFBH low limit is alleged to be nearer to 10.3 v. so the circuit should not be being overridden and in confirmation the ATC ventilation operates as it should.
I've asked for a cold morning FFBH operation with the battery "on charge" (i.e. circa 13+ v) so as to be sure that the problem is not low voltage related. If this doesn't shed some light on the situation I'm almost out of ideas.
Any further suggestions. Stuart

2006-2009 Range Rover MkIII / L322
9 Posts
Hi there,
I'm having the exactly the same symptoms with my RR TDV8. The heater will run when the car has started & temperatures are cold enough but it won't come on using the timer or the remote. We have tried the fuse reset but still no joy. Just wondered if you got to the bottom of it without having to replace half the car? I'm in need of a Guru I think!
Kind regards
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