FBH outside temp sensor location pls?

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Ross Tait

Active Member
Posts
207
Location
Edinburgh
hey folks, I have finally fitted a new fbh fuel pump to my lands and it’s sub zero outside, but when I started the car no fbh startup, usually the fans starts within a min or two and the system fires up, but nothing at all. Months ago I broke the fbh fuel pump whilst changing the main diesel filter, i accidentally snapped a pipe off it whilst trying to remove the fuel hose, so I unplugged the fbh fuel pump at the time to stop it pumping diesel all over the road on cold mornings. I’ve just finally replaced the fuel pump and plugged it back in assuming it would come back to life first cold start but it’s failed. So I’m looking for the outside temp sensor location. Now I’ve looked in the workshop manual and I know it’s around the nsf headlamp/radiator area but I can’t see it for the life of me. When you look at different system illustrations they show different images which are slightly conflicting. If anyone could offer a well worded description it would be much appreciated as it’s not gonna be warm in Scotland for a while now and that fbh makes a big difference so I really need it back on.

Any help much appreciated. Also I know if I pull it all apart i would eventually find it but it’s sub zero outside and my plan is to unplug and short the pins of the sensor to test whether it’s the fbh at fault or power supply/sensor etc and I’m hoping I can do that without taking its whole face off.

I’m hoping someone knows exactly where it is.

Many thanks, ross
 
The environmental sensor is behind the front bumper, on the UK driver's side. The bumper needs removing to access it.

Have you pulled fuse 5 to reset the FBH? If the pump was faulty, the FBH will shut down after a few failed firing attempts. Pulling fuse 5 will reset the FBH ECU. ;)
 
Nodge68 said:
The environmental sensor is behind the front bumper, on the UK driver's side. The bumper needs removing to access it.

Have you pulled fuse 5 to reset the FBH? If the pump was faulty, the FBH will shut down after a few failed firing attempts. Pulling fuse 5 will reset the FBH ECU. ;)
Click to expand...

Hi there, yes I have tried pulling fuse no 5 under the bonnet for 7/8 mins but still no attempt for it to start up. From memory the fan used to start within 2/3 mins of engine startup or even just ign on.

I’ve managed to find the sensor so thanks! It is in a crap spot! I may attempt to remove the upper most bumper screws and squeeze my arm down there (I’m pretty skinny) as I may be able to reach the plug.

I’m really hoping it’s just the sensor that’s gone and not the whole unit. It has had about a 3-6 month nap.

Cheers, ross
 
So this is getting interesting already.
I removed the fuse for over five min and nothing. So unsure if the replacement pump was operational i decided to start knocking off potential issues. I removed the osr wheel, peeled the arch back and put 12v to the little pump from a motorcycle battery and it clunked as I’d expect a solenoid to do. I then put a test lamp into the pumps plug and started the car after again removing the fuse for five min but the lamp didn’t light so no sign of system attempting to start. So decided the outside temp sensor would be next.

So I’ve undone the bumpers 4 uppermost screws then pulled the bumper back and gently pushed a wooden door wedge down there to make a 2” gap. From there I could see the top of the outside temp sensor. I used a 24” pry bars tip as if it were a screwdriver to push in the sensors plug retaining spring, then whilst pushing the release spring in I pulled the bar upward to remove the plug from the sensor. I then used welding wire with a hook on the end (coat hanger will do) to hook the plug up and pull it up out the gap at the top of the bumper, I then fed it under the valance bit using another hook and pulled it along the top side of the radiators corner into the engine bay, now I’ve cable tied it to something to keep it there for testing.

After that first thing I noticed looking back down at the sensor was that it was full of water in the sensor where the connector pins are (at which point I distinctly remembered having fun last March driving through flood waters).

I then jumped the sensor plugs two pins with a mini blade 20 amp fuse with its pins bent slightly inward and again removed the fuse number 5 for 5 mins. Then started the car but still nothing, no fans and no mini fuel pump activity. I guess I may have gotten water right into the fbh or it’s plug so the next step will be to check the power which I have at the sensor plug is making it to the fbh’s plug to activate it. I hope it’s not dead lol. Although there’s loads of them in breakers.


Cheers
 
I'm currently trying to get my L322 FBH to work and would guess the freelander is similar.
Just incase you don't know the fuel pump is a pulse type so each time you put 12v on it it will do 1 pump, you need to keep applying and removing the 12v to prime the system if it's the same as the L322.
IMO it uses the same temperature sensor as the car so what does that say on the dash or where ever it is?
IMO you should only need to remove the fuse for around 30 seconds to clear the ecu.
 
backinblack said:
I'm currently trying to get my L322 FBH to work and would guess the freelander is similar.
Just incase you don't know the fuel pump is a pulse type so each time you put 12v on it it will do 1 pump, you need to keep applying and removing the 12v to prime the system if it's the same as the L322.
IMO it uses the same temperature sensor as the car so what does that say on the dash or where ever it is?
IMO you should only need to remove the fuse for around 30 seconds to clear the ecu.
Click to expand...

Hi there, thanks for the info, very useful as I did pulse power to the pump and it did exactly as it should so I guess the pumps fine. On the freelander there’s a specific outside sensor just for the fbh. On this system power goes from alternator to ecu then when ign or engine on (not sure which) the ecu sends power to the sensor which is just visible through the front bumper lowermost central grill area, within that area it’s at the top edge about 5” or so from left side. This sensor is open circuit above 5 Celsius and closed circuit below sending power to the fbh internal ecu, this voltage should wake up the ecu and initiate its startup procedure. The fbh ecu then controls its own operation independently. I’m about to read up on the startup procedure of the fbh and also it’s pin outs.

Only success I’ve had is that I’ve heard the fbh coolant circulation pump run once and that was with engine off but ign on.

Thanks for the 30sec fuse info as it’s freezing outside and each 5 mins feels a lot longer lol.

Will update again as it may help others in future.

Cheers
 
Ross Tait said:
So this is getting interesting already.
I removed the fuse for over five min and nothing. So unsure if the replacement pump was operational i decided to start knocking off potential issues. I removed the osr wheel, peeled the arch back and put 12v to the little pump from a motorcycle battery and it clunked as I’d expect a solenoid to do. I then put a test lamp into the pumps plug and started the car after again removing the fuse for five min but the lamp didn’t light so no sign of system attempting to start. So decided the outside temp sensor would be next.

So I’ve undone the bumpers 4 uppermost screws then pulled the bumper back and gently pushed a wooden door wedge down there to make a 2” gap. From there I could see the top of the outside temp sensor. I used a 24” pry bars tip as if it were a screwdriver to push in the sensors plug retaining spring, then whilst pushing the release spring in I pulled the bar upward to remove the plug from the sensor. I then used welding wire with a hook on the end (coat hanger will do) to hook the plug up and pull it up out the gap at the top of the bumper, I then fed it under the valance bit using another hook and pulled it along the top side of the radiators corner into the engine bay, now I’ve cable tied it to something to keep it there for testing.

After that first thing I noticed looking back down at the sensor was that it was full of water in the sensor where the connector pins are (at which point I distinctly remembered having fun last March driving through flood waters).

I then jumped the sensor plugs two pins with a mini blade 20 amp fuse with its pins bent slightly inward and again removed the fuse number 5 for 5 mins. Then started the car but still nothing, no fans and no mini fuel pump activity. I guess I may have gotten water right into the fbh or it’s plug so the next step will be to check the power which I have at the sensor plug is making it to the fbh’s plug to activate it. I hope it’s not dead lol. Although there’s loads of them in breakers.


Cheers
Click to expand...

You're doing well to get the FBH under water, as it's quite high and has an exhaust with a U bent to prevent water entering the burner. Although I suspect the ECU although sealed, could get damaged from prolonged submersion.

The wires at the sensor plug simply need joining together, to trigger the FBH to fire. I can't remember the colours now, but one wire comes from the EDC for the engine running signal, the other wire is the run trigger to the FBH. Connecting the run wire to the battery + terminal will fire the FBH, even if the engine is off.

Don't connect the dosing pump to 12v for more than a second or so, as it's a pulse pump. The FBH pulses the pump at various speeds, to change the firing rate of the burner.
 
Cheers Ross, I did watch a youtube video on someone fixing his freelander fbh that was very interesting. I wish mine wasn't tied to the car so much as it's a right pita.:D
 
Nodge68 said:
You're doing well to get the FBH under water, as it's quite high and has an exhaust with a U bent to prevent water entering the burner. Although I suspect the ECU although sealed, could get damaged from prolonged submersion.

The wires at the sensor plug simply need joining together, to trigger the FBH to fire. I can't remember the colours now, but one wire comes from the EDC for the engine running signal, the other wire is the run trigger to the FBH. Connecting the run wire to the battery + terminal will fire the FBH, even if the engine is off.

Don't connect the dosing pump to 12v for more than a second or so, as it's a pulse pump. The FBH pulses the pump at various speeds, to change the firing rate of the burner.
Click to expand...

Hey, haha yeah I’m quite an adventurous freelander owner, there was mega floods earlier in the year and we drove about a quarter mile back and forth along it just for kicks. I remember looking out the window and the water was easily half way up the wheel, I remember being fairly surprised it wasn’t coming inside somewhere so I guess there’s plenty space for continual submersion as even the flow of water off the wheels was impressive even at low speeds.

Yeah I’ve jumped the sensor wire, managed to get to it without removing the bumper. Also I did just pulse test the pump and it’s running fine.

Ah that’s interesting I did want to try to have it running with the engine off as it’ll be easier to hear all the individual fbh components in action which may help identify the dud thanks I’ll try that tomo morning once she’s cold again as I just got back from picking the wife up from work.

I have what wiring diagrams and system operation description here and from what I understand the fact I’ve heard the fbh coolant circulation pump running is a good sign. Will find out more tomo morning.

Cheers
 
Ok so I’ve had a break through with this one. I went out today and pulled the fuse to reset the thing. Then sent power straight to the silver green wire (sensor to fbh) but nothing happened. Tried starting it and battery was flat (hours of diagnostics for days on multiple vehicles with doors open etc) so quick jump start and she ran, I then bridged the outside temp sensor plug and within a minute the fbh started up! Woohoo I didn’t drown it! So she’s ran a while and then stops a few times but after replacing the fuel pump I know there will be air pockets in the fuel line so I just keep pulling fuse 5 to reset the ecu and it restarts instantly again. Few more episodes of that and the fuel system will purged of air and I expect she’ll work like she used to.

So thanks for all the help and info folks I got a lot of useful info from you guys on this and that’s helped me fix it a lot quicker.

Next target is my heated front screen that’s never worked in my ownership, so I’m off to print the wiring diagrams for that next lol.

Thanks again and happy new year to all!

Cheers
 
Ross Tait said:
Ok so I’ve had a break through with this one.
Click to expand...

Excellent stuff. ;)

Ross Tait said:
Next target is my heated front screen that’s never worked in my ownership, so I’m off to print the wiring diagrams for that next lol.
Click to expand...

The heated front screen wiring isn't complicated, but it is controlled by the CCU, so you need to check the relay is being energised.
 
Hi there just to mention I’ve just finished wiring up a switch to the fbh so it doesn’t keep coming on when doing short distances,all I did was connect a switch the the two wires from the outside temp switch to a switch in the freelander and I can now switch it on or off when ever I want,as before it used to come on nearly all the time as I think the temp switch had gone faulty so cut the wires to the temp switch but now rewired to a switch and it’s great,did take a few attempts with the fuse to get the fuel through
 
Nodge68 said:
Excellent stuff. ;)



The heated front screen wiring isn't complicated, but it is controlled by the CCU, so you need to check the relay is being energised.
Click to expand...

Hey, thanks very much for the heads up, I think (and hoping) it’ll be an easy fix as at least the light illuminates when the button pressed. I shall go investigate which relay and fuses to look into.

Thanks

fastasulike72 said:
Hi there just to mention I’ve just finished wiring up a switch to the fbh so it doesn’t keep coming on when doing short distances,all I did was connect a switch the the two wires from the outside temp switch to a switch in the freelander and I can now switch it on or off when ever I want,as before it used to come on nearly all the time as I think the temp switch had gone faulty so cut the wires to the temp switch but now rewired to a switch and it’s great,did take a few attempts with the fuse to get the fuel through
Click to expand...

Yeah, that’s a good idea. I like the switch idea as I would actually like it to come on at times in the past as it was freezing but being just above 5c it wouldn’t. Would be nice to make the decision myself. As for now I’ve shoved a small blade 20 amp fuse in the temp sensor plug so its set to run always until engines warm. Everything’s frozen here now so can probably just leave that in there till about March hahaha. Then I’ll go big a wee switch that lights up. :D

Cheers
 
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