CDT - FBH 10v problem - volunteers needed

JohnFol · 19th February 2007, 13:29

Like several others I have a non-functioning FBH. The symptoms seem to be the pump does not work, and hence the heater remains cold, even though the fan starts etc.

The reason seems to be the pump connector has 10V on it that is not effected by the timer/temperature and it remains at 10v (i.e. no pulsing). The supply is unable to supply any current, and hence drive the pump.

The current school of thought is it is probably the circuit board, but it could also mean the processor is responding to something and is deliberately not firing the pump.

The only way to help determine what has failed is to try a mechanically known good FBH with a suspect PCB.

What would be good is if we could arrange for someone with a known good FBH to swap the PCB (4 screws / 4 block connectors) with someone who has the problem.

To help this along, I am in the Reading area and am quite happy for someone to try their PCB in my FBH. If you are local, let me know. (I also work in Portsmouth / Farnborough / Guildford)

If there is anyone else prepared to do this, could you add your name / location?

ta!

myjess · 19th February 2007, 20:03

BY pump, do you mean the fuel pump in the engine bay. Is the fule sensor OK on top of the fuel filter. I know if I play about in there that my pump doesn;t come on and so the car won't start, but you do not mention any starting problems.

simpsora · 20th February 2007, 18:03

Good thinking JohnFol, the above action would certainly prove once and for all if the fault with FBH's (which seems to be an increasing numbers of non-working units ,displaying same fault condition) is on circuit board or 'something else'.
I would gladly send you my PCB but as I have exactly same fault as your's then there wouldn't be much point!
The increasing No. of non-working webasto's can't be very good for the webasto company's reputation. They are bound to know what is causing this 'common' fault, perhaps if we 'gathered' a list of owner's and serial No. of faulty webasto
and made a joint approach to webasto, expressing our 'dissapointment' with the
poor performance of their expensive product then we may 'shame' them into providing details of 'a cure' (not just PCB exchange at great cost!).Strength in numbers! .Just a thought.
Thanks.

JohnFol · 20th February 2007, 19:38

welcome comrade simpsora-the-red.

The fact you have a failing unit means there is one more volunteer just waiting to be paired up. where in the contry are you?

black olive · 21st February 2007, 13:01

spoke to the guy at Webasto today who did work on the development of the heater units for MGR, and the information I gleaned is reproduced below. It may give a few pointers as to why so many installs apparently have faulty heaters even though all the conditions for them to work "appear" to heva been met.

hope this is of some use, moderators, is it worth making this a sticky, or perhaps merging with another thread on fault finding ?

The heater units supplied to MGR differ to those available off the shelf as part of a kit to fit yourself to a boat etc, in the following way.

Different pin configuration on the 6 pin connector
Coolant temps for switch over to idle.
Different software install ( was to enable diagnostics via T4, but never implemented).

1) measuring the voltage at the fuel pump outlet with a DVM or similar is a bit fruitless, as in certain run conditions this can appear to be sat at a high voltage level, whereas a DC coupled oscilloscope would show that the line is actually pulsing ( the width of the negative pulses controls the amount of fuel pumped).

The heaters are (obviously) designed to fail safe, and lock out if all the conditions for their safe running are not met, the only sure fire way to diagnose any lock out conditions due to other inflences on the system, or faults with the the heater itself is to use the webasto diagnostic tool (webasto diagnostics were never implemented in T4), available at any webasto dealer ( or I believe can be obtained from ebay).this will interrogate the controller IC for any logged faults or lockouts.

2) Early cars were released with fuel line joiners which reduced the effective inner diameter of the fuel lines at the joint points to 0.8mm ID, this led to problems due to lack of fuel being supplied to the burner, causing lock out due to lack of fuel.Worth checking your fuel line runs, particularly as over the years these joiners may have become blocked with small particles of crud.

3) a batch of vehicles were released with potentially duff temperature sensors, so the heaters will never kick in unless commanded by telestart or similar ( to test your heater is working put 12V on pin 3 when the car is running and the heater should fire up). the sensor should switch between open and closed circuit at 5 degrees celcius.

4) Not all vehicles left the factory with the fuel lines to the FBH correctly primed- so the heaters on these vehicles will never have worked. The solenoid pumps have to be gravity fed and are not self priming.

5) finally and most worringly, the units were carried over from a BMW deign, and had an inherent fault in that if the units are disconnected, the 2 way connector has to be inserted before the 6 way connector otherwise a chip in the control unit will blow. Webasto were not allowed to design this fault out for MG rover (cost) , so a number of units particularly those obtained from scrappers and retrofitted may be damaged in this manner.

I did ask on the availability of a circuit diagram. the response was that all the pertinent IP rights had been passed to MG Rover, so this information was no longer available via webasto.

also dont forget, each time the unit locks out for whatever reason, it will need to be reset.

simpsora · 21st February 2007, 17:29

Hi JohnFol
I live in Aberdeenshire (Scotland) . I have a 2001 CDT ,65,000 mls. Only thing that doesn,t work on it is the webasto!

PS. interesting stuff posted by 'moodybluezt' especially, paragraph 2 .I can get my dosing pump to 'click' by applying 12v on and off (otherwise 10. 4 v steady on multiplug) but the output of disconnected fuel supply pipe at FBH (pipe in jam jar!)is still a bit pathetic , and I do have fuel line joiners !

black olive · 21st February 2007, 20:25

hope its helped- I guess at 5kw output, a good supply of fuel will be required, and if the unit doesnt get to a preset temperature within a preset time it will lock out.

Roverron · 22nd February 2007, 09:08

The problem is that if the pump is not being pulsed then fuel supply restrictions, lack of it being primed, time outs etc are all irrelevant.

After being reset, the pump must start in the same way that the water pump and fan does.
If it did and the heater timed out due to a fuel supply/priming issue, then this would be understandable.

Something is preventing the fuel pump from being pulsed....

The igntor in mine works - it takes about 15amps, but, like the fuel pump, it is not being energised by the controller. The mosfet that supplies it is not being switched on (the mosfet is not open circuit).

So for whatever reason the pump is not being energised, also applies to the ignitor.
I have tried 12V to pin 1 and gnd to pin 3 and both switch on the fan and water pump and the fbh does its 3 attempts to fire up before shutting down. So the ecu is not totally dead or it would do this.

The only way to pinpoint the problem is to swap a suspect pcb onto a working heater.

Ron

black olive · 22nd February 2007, 13:27

Ron, whilst I agree with your comments, putting a suspect PCB onto an otherwise working system will still only confirm that the control unit PCB is faulty. ( which you suspect anyway), it will not tell you why the PCB is faulty, hence the use of the webasto diagnostics tool, that should go a stage further. unfortunately, it would appear that the possibilities of obtaining circuit diagrams in order to further fault find are fairly limited

JohnFol · 22nd February 2007, 13:42

One thing that crossed my mind is that both Ron and I have recently changed in-tank pumps, which may have introduced air into the fuel line to the FBH.

For a layman like me, I could imagine the PCB may not work if another component is failing, for example it cannot pass a current to the glow plug, if there is a high resistance on the pump, or some other test that is failing. To eliminate all of these in 1 go, it does seem reasonable to swap the PCB.

I agree it may not establish the "why", but I suspect this would confirm the PCB that needs further investigation.

19th February 2007, 13:29	#1
JohnFol Gets stuck in 75 Conn SE - XVWY* Join Date: Nov 2006 Location: Reading Posts: 564 Thanks: 0 Thanked 2 Times in 2 Posts	CDT - FBH 10v problem - volunteers needed Like several others I have a non-functioning FBH. The symptoms seem to be the pump does not work, and hence the heater remains cold, even though the fan starts etc. The reason seems to be the pump connector has 10V on it that is not effected by the timer/temperature and it remains at 10v (i.e. no pulsing). The supply is unable to supply any current, and hence drive the pump. The current school of thought is it is probably the circuit board, but it could also mean the processor is responding to something and is deliberately not firing the pump. The only way to help determine what has failed is to try a mechanically known good FBH with a suspect PCB. What would be good is if we could arrange for someone with a known good FBH to swap the PCB (4 screws / 4 block connectors) with someone who has the problem. To help this along, I am in the Reading area and am quite happy for someone to try their PCB in my FBH. If you are local, let me know. (I also work in Portsmouth / Farnborough / Guildford) If there is anyone else prepared to do this, could you add your name / location? ta!

22nd February 2007, 09:08	#8
Roverron Gets stuck in Rover Join Date: Nov 2006 Location: Tarbert Posts: 980 Thanks: 0 Thanked 19 Times in 9 Posts	The problem is that if the pump is not being pulsed then fuel supply restrictions, lack of it being primed, time outs etc are all irrelevant. After being reset, the pump must start in the same way that the water pump and fan does. If it did and the heater timed out due to a fuel supply/priming issue, then this would be understandable. Something is preventing the fuel pump from being pulsed.... The igntor in mine works - it takes about 15amps, but, like the fuel pump, it is not being energised by the controller. The mosfet that supplies it is not being switched on (the mosfet is not open circuit). So for whatever reason the pump is not being energised, also applies to the ignitor. I have tried 12V to pin 1 and gnd to pin 3 and both switch on the fan and water pump and the fbh does its 3 attempts to fire up before shutting down. So the ecu is not totally dead or it would do this. The only way to pinpoint the problem is to swap a suspect pcb onto a working heater. Ron __________________ [SIGPIC][/SIGPIC] Click to visit my website Ron on Twitter MyFacebook page

19th February 2007, 20:03	#2
myjess Avid contributor Rover 75 CDT Join Date: Dec 2006 Location: Stokesville Posts: 115 Thanks: 0 Thanked 0 Times in 0 Posts	BY pump, do you mean the fuel pump in the engine bay. Is the fule sensor OK on top of the fuel filter. I know if I play about in there that my pump doesn;t come on and so the car won't start, but you do not mention any starting problems.

20th February 2007, 18:03	#3
simpsora Regular poster 2001 2.00 CDT 116 bhp Join Date: Nov 2006 Location: aberdeenshire Posts: 97 Thanks: 1 Thanked 1 Time in 1 Post	Good thinking JohnFol, the above action would certainly prove once and for all if the fault with FBH's (which seems to be an increasing numbers of non-working units ,displaying same fault condition) is on circuit board or 'something else'. I would gladly send you my PCB but as I have exactly same fault as your's then there wouldn't be much point! The increasing No. of non-working webasto's can't be very good for the webasto company's reputation. They are bound to know what is causing this 'common' fault, perhaps if we 'gathered' a list of owner's and serial No. of faulty webasto and made a joint approach to webasto, expressing our 'dissapointment' with the poor performance of their expensive product then we may 'shame' them into providing details of 'a cure' (not just PCB exchange at great cost!).Strength in numbers! .Just a thought. Thanks.

20th February 2007, 19:38	#4
JohnFol Gets stuck in 75 Conn SE - XVWY* Join Date: Nov 2006 Location: Reading Posts: 564 Thanks: 0 Thanked 2 Times in 2 Posts	welcome comrade simpsora-the-red. The fact you have a failing unit means there is one more volunteer just waiting to be paired up. where in the contry are you?

21st February 2007, 13:01	#5
black olive I really should get out more....... 260 SE vin 214 ( last mark 1 260 ) Join Date: Dec 2006 Location: Lancashire Posts: 2,009 Thanks: 1 Thanked 8 Times in 4 Posts	spoke to the guy at Webasto today who did work on the development of the heater units for MGR, and the information I gleaned is reproduced below. It may give a few pointers as to why so many installs apparently have faulty heaters even though all the conditions for them to work "appear" to heva been met. hope this is of some use, moderators, is it worth making this a sticky, or perhaps merging with another thread on fault finding ? The heater units supplied to MGR differ to those available off the shelf as part of a kit to fit yourself to a boat etc, in the following way. Different pin configuration on the 6 pin connector Coolant temps for switch over to idle. Different software install ( was to enable diagnostics via T4, but never implemented). 1) measuring the voltage at the fuel pump outlet with a DVM or similar is a bit fruitless, as in certain run conditions this can appear to be sat at a high voltage level, whereas a DC coupled oscilloscope would show that the line is actually pulsing ( the width of the negative pulses controls the amount of fuel pumped). The heaters are (obviously) designed to fail safe, and lock out if all the conditions for their safe running are not met, the only sure fire way to diagnose any lock out conditions due to other inflences on the system, or faults with the the heater itself is to use the webasto diagnostic tool (webasto diagnostics were never implemented in T4), available at any webasto dealer ( or I believe can be obtained from ebay).this will interrogate the controller IC for any logged faults or lockouts. 2) Early cars were released with fuel line joiners which reduced the effective inner diameter of the fuel lines at the joint points to 0.8mm ID, this led to problems due to lack of fuel being supplied to the burner, causing lock out due to lack of fuel.Worth checking your fuel line runs, particularly as over the years these joiners may have become blocked with small particles of crud. 3) a batch of vehicles were released with potentially duff temperature sensors, so the heaters will never kick in unless commanded by telestart or similar ( to test your heater is working put 12V on pin 3 when the car is running and the heater should fire up). the sensor should switch between open and closed circuit at 5 degrees celcius. 4) Not all vehicles left the factory with the fuel lines to the FBH correctly primed- so the heaters on these vehicles will never have worked. The solenoid pumps have to be gravity fed and are not self priming. 5) finally and most worringly, the units were carried over from a BMW deign, and had an inherent fault in that if the units are disconnected, the 2 way connector has to be inserted before the 6 way connector otherwise a chip in the control unit will blow. Webasto were not allowed to design this fault out for MG rover (cost) , so a number of units particularly those obtained from scrappers and retrofitted may be damaged in this manner. I did ask on the availability of a circuit diagram. the response was that all the pertinent IP rights had been passed to MG Rover, so this information was no longer available via webasto. also dont forget, each time the unit locks out for whatever reason, it will need to be reset.

21st February 2007, 17:29	#6
simpsora Regular poster 2001 2.00 CDT 116 bhp Join Date: Nov 2006 Location: aberdeenshire Posts: 97 Thanks: 1 Thanked 1 Time in 1 Post	Hi JohnFol I live in Aberdeenshire (Scotland) . I have a 2001 CDT ,65,000 mls. Only thing that doesn,t work on it is the webasto! PS. interesting stuff posted by 'moodybluezt' especially, paragraph 2 .I can get my dosing pump to 'click' by applying 12v on and off (otherwise 10. 4 v steady on multiplug) but the output of disconnected fuel supply pipe at FBH (pipe in jam jar!)is still a bit pathetic , and I do have fuel line joiners !

21st February 2007, 20:25	#7
black olive I really should get out more....... 260 SE vin 214 ( last mark 1 260 ) Join Date: Dec 2006 Location: Lancashire Posts: 2,009 Thanks: 1 Thanked 8 Times in 4 Posts	hope its helped- I guess at 5kw output, a good supply of fuel will be required, and if the unit doesnt get to a preset temperature within a preset time it will lock out.

22nd February 2007, 13:27	#9
black olive I really should get out more....... 260 SE vin 214 ( last mark 1 260 ) Join Date: Dec 2006 Location: Lancashire Posts: 2,009 Thanks: 1 Thanked 8 Times in 4 Posts	Ron, whilst I agree with your comments, putting a suspect PCB onto an otherwise working system will still only confirm that the control unit PCB is faulty. ( which you suspect anyway), it will not tell you why the PCB is faulty, hence the use of the webasto diagnostics tool, that should go a stage further. unfortunately, it would appear that the possibilities of obtaining circuit diagrams in order to further fault find are fairly limited

22nd February 2007, 13:42	#10
JohnFol Gets stuck in 75 Conn SE - XVWY* Join Date: Nov 2006 Location: Reading Posts: 564 Thanks: 0 Thanked 2 Times in 2 Posts	One thing that crossed my mind is that both Ron and I have recently changed in-tank pumps, which may have introduced air into the fuel line to the FBH. For a layman like me, I could imagine the PCB may not work if another component is failing, for example it cannot pass a current to the glow plug, if there is a high resistance on the pump, or some other test that is failing. To eliminate all of these in 1 go, it does seem reasonable to swap the PCB. I agree it may not establish the "why", but I suspect this would confirm the PCB that needs further investigation.