Webasto FBH - Help me diagnose failure?

landyhaze said:

Ah, there should be some way to read the coolant inlet temperature, and by the look of your instrument binnacle it should be close to 85. The FBH is supposed to stop at something near 65 I think?

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I am going to try and take a video of the FBH and how mine is running, there is some screen shots with temp getting up 67c but the FBH still keep on running.

UPDATE

According to the Disco_3_FBH_Workshop_manual_thermo_top_V.pdf the FBH runs full out until the temperature reaches 80 C, then runs at half power until it gets to 90 C. It won't switch back on until the temp falls again to 75 C. This is fairly close for a thermostat of 88. Of course the manual says the temperature set points can be altered by the customer-specifications.

My ?guess? is you have two problems. 1) the 5 Celsius switch is closing at way above 5 Celsius, and 2) Your thermostat is on the way out, and only regulating to 85 C, which is enough to confuse the FBH. These are both common faults, apparently.

If it were my landy I would replace the switch and the thermostat, but I might be tempted to try to alter the customer specific setpoints from 80,90,75 to 75, 85, 60..if I had a hawkeye

landyhaze said:

UPDATE

According to the Disco_3_FBH_Workshop_manual_thermo_top_V.pdf the FBH runs full out until the temperature reaches 80 C, then runs at half power until it gets to 90 C. It won't switch back on until the temp falls again to 75 C. This is fairly close for a thermostat of 88. Of course the manual says the temperature set points can be altered by the customer-specifications.

My ?guess? is you have two problems. 1) the 5 Celsius switch is closing at way above 5 Celsius, and 2) Your thermostat is on the way out, and only regulating to 85 C, which is enough to confuse the FBH. These are both common faults, apparently.

If it were my landy I would replace the switch and the thermostat, but I might be tempted to try to alter the customer specific setpoints from 80,90,75 to 75, 85, 60..if I had a hawkeye

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Hi Landyhaze.
Once again sorry for not using your real name as so many members on this forum do not have there names showing.

Yes I agree with the thermostat maybe not working as with the FL as with the R75 M47 engine they tend to fail open or start going weak then fail completely, and as such would have a baring on the FBH, I have yet to confirm for sure that the thermostat is failing, or as failed open so I can maybe try the inline top stat.

The 5 Celsius switch you are referring to would this be the ambient temperature switch on the bumper crash bar ? , or could the coolant switch be faulty cheers Arctic2.

Tried mine again this morning and true enough, it doesn't work.

I found this info from FrenchMike which may prove useful:

WEBASTO FBH DIAGNOSTICS update

-Engine cold and stopped

-At first, unplug then replug the power connector (or fuse F8) in order to reset the system.
-Connect permanently Pin 3 to earth. (To + batt in case of older model)
Simultaneously start a TIMER and listen when the fan stops

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 (send me a PM)

IF a weird turbine noise appears at a door opening e.g.,PCB likely faulty.

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.)

Mike

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Mine stopped at around 4mins 5 secs so looks like I'm looking at the glow plug. But also looked for the doser pump and found a lump of rust suspended by the fuel lines...

So, for me I may be looking at almost a full refurb.

Does anyone have a picture of how the fuel pump should be attached to the car? Does it use the usual rubber mount or is it something unique?

Wow, has it really been a whole year since I last played with the FBH? Well, I made some progress today, I managed to build a K-line interface, and got it to talk to my FBH using the Webasto software on a laptop. You simply connect to the Diagnostic K-bus connector, and turn on the ignition, then select the "C/Z Rover" option and I was able to read the fault history, and some sensor info. I reset the faults, but the Webasto firmware will only allow me to do a 'prime' operation, I am not able to start the FBH and get that lovely Smoke display. The circuit I made was based on the L9637 K-bus chip, a voltage regulator and a RS232 level chip. You only need three wires to the Freelander, and three wires to the laptop. I guess my next step is to remove the front bumper, and swap over the FBH. Before I buy a FBH of questionable history off eBay I would like to confirm the dosing pump is okay though first. It seems odd the priming operation would not let me then start the heater, is there a fuel pressure sensor someplace?
-Hazel

Another update. I removed the F5 fuse, waited for 10 seconds and reinstalled it. Started the engine and then connected the laptop as before. Now I can see the FBH going through its start-up sequence. The webasto software allows you to make a log of the various readings, however the software kicks you out when a fault occurs, so you have to reconnect again quickly to get more data. So it seems I am getting a fault during the flame detector phase. I think the glow plug is used as a flame detector, and I am still unsure if the thing has lit, the exhaust is still cold, so I haven't managed to determine if the dosing pump is working correctly? On a previous run I did see a bit of smoke, but none during the two logged runs I did.
-Hazel

It could be the PCB on the FBH these can also fail, we at the R40 forums send ours out to French Mike whom repairs them for us and we are up and running again, we also remove the FBH and give it a decoke links below, for refitting testing etc thanks goe's to Keith, Steve, Harry, & Brian, for these how to's on cleaning the FBH etc..
http://www.the75andztclub.co.uk/forum/showthread.php?p=877768#post877768

Heres the k-line interface I knocked up:




And a close up of the PCB:


I also bought a used FBH off the 'bay and will try powering it up to test the dosing pump I have. If it is just a PCB failure on the old unit, I think I will be able to resolder it and make it good (fingers crossed).
I did join the 75 group but they cancelled my membership a few hours later, I guess they are not keen on us Freelander types.

New "pattern" pump looks like this:


A replacement used pump from Germany (it was reasonably priced):


My test rig:


Some yuk:


Results of using the 60 second Webasto 'Fuel Prime':
New pump transfers 24 to 25cc
Old pump transfers 20 to 23cc
So not quite an exact match, I would expect the new pump to run a bit rich, and I am guessing you would tune this in with the CO2 adjustment ? Anyway I can't get any further as the "Good working order" FBH I bought off ebay stops at the "Glowplug/Flame Monitor Short Circuit" Fault. I am loath to take it apart and fix it when the seller sold it to me for £80 as a working unit. Any Advice?
-Hazel

Mixture / co can be set with a software but you will need a CO analyser to check the actual level at the flu / exhaust.

Contact seller, tell them that the unit is busted and you want another without paying the postage for the return of the faulty unit.

Mmmm good advice, I suspect the seller will just ignore me.

landyhaze said:

Mmmm good advice, I suspect the seller will just ignore me.

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That's what the feedback and dispute process is for. If you payed with PayPal or a credit card, you can claim your money back

Success! I got bored with waiting for the ebay seller to reply to me so I took the control PCB out of the unit, reverse engineered the glow plug drive circuit, figured out how it should work, and started checking the main stressed components, and found a dead resistor right away. Replaced the resistor with a 31p one from Farnell (it arrived 24 hours later for the princely sum of £3.40). I reassembled it [my eBay FBH] and hooked it up to a battery, a laptop, some diesel and a bucket of water, primed the pump, and connected the 'go' wire - its ALIVE! This FBH hardly made any smoke at all during start-up, and within 10 minutes I had a bucket of 72 degress hot water! I have some photos, but Photobucket is down for maintenance at the moment. The only remaining problem I have is that the two gaskets that 'seal' the PCB have both swelled up by 20% and will no longer fit. I suspect this is to do with the large amounts of diesel and oil I found inside and all over the PCB.
Now I have to figure out how to get the FL1 facelift front bumper off and replace the dead FBH. Progress.
-Hazel

Photobucket is back up so here is some "showing-off by pictures".
Figuring it out:


Remove dead bit:


New bit arrives, sort of looks like the dead bit.


All together for another test, although without gaskets on the PCB cover.


WTT info looks good:


Water gets to 72 C, and then it does a burn-off and shuts down. The CO detector didn't go off either.

Excellent thank you for sharing your findings, these are the sort of jobs that will help us all keep on top of our FL 1

Hi Arctic2, my pleasure! I haven't fitted it to the truck yet. In the mean time I accidentally ordered a Telestart kit, T91 ECU from UK, a LR remote from Lithuania, and an Aerial and connector from Poland. All in £100. I'm looking forward to pressing the button to make the FBH heat up the truck from inside the house.
-Hazel

Oo the LR remote kit, nice. I was going to order a cheap remote relay from fleabay because I'm on a budget. I might be tempted to get 1533 oval timer, maybe for a birthday present. I'm trying to find the FBH connector at the moment so I can add automatic heater start up into the mix.

All the connectors are readily available of fleabay, the link I put up for the dosing pump belongs to a seller that also sold me a set of the FBH connectors. If you are on a budget, I would suggest wiring in two switches. One to activate the FBH (it will run using the same input from the temperature sensor on the bumper) , and one to over-ride the heater fan so the fan runs without the 'ignition' switched on. Then in the future, you can easily wire in a timer or a remote, or both,

I have a Telestart T90 to fit to my sons MGZT and an FBH as soon as we get time

My T91 ECU and Remote arrived by Royal mail this morning (No sign as yet of the wiring or antenna from Poland). Anyway being impatient I decided to hook it up and pair the remote to the ECU. I checked the remote battery condition, 3.2V, and then hunted for the installation instructions - webasto only sell looms, but I did eventually figure out the connector was close to a Molex KK 6 pin, which I modified bit to get three connections. Pin 1 12v, Pin 6 GND, and Pin 3 is a 12v output to a LED, which lights the LED when the remote is pressed. Followed the instructions in the user manual, and synched the remote up right away, even with antenna. I hope the TX stage is alright, as I didnlt realise the ECU sends confirmation signals back to the remote to make it flash every few seconds. Anyway my £80 flutter seems to have been worth while. A few websites show the W-bus being connected on Pin 2, and a temperature sensor on pin 5, and a timer on 4. Surely the W-bus isn't really needed? The penultimate piece in the Jigsaw is to see if the FBH will power up using a different pin to the 12V supply via the temperature switch in the front bumper, and finally to see if the Cooling fan output is immediate (flattens battery needlessly) or waits for the coolant to start getting warm.
PS I forgot to mention that the W-bus is only on the VW version of the FBH (we have the K-bus), and the VW version of the T91 ECU seems to work fine with the LandRover version of the T91 remote. All good.