Technical no main beam

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Technical no main beam

he trys hard

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hi new member looking for some advice please I have a 2007 fiat ducato based camper a couple of weeks ago I lost main beam. I did a little looking about and found that the steering column stalk unit switch could be a fault so I bought a second hand one and fitted today but still have same problem, all other lights work but the main beam and flash and no dash blue light indicator fuse's good cant hear any clicking from relay by fuse I did try swapping relays with other the same but no good any help would be very much appreciated thanks ian
 
The functions you describe are carried out by the body control module. I have not got the circuit to hand but there will be a single relay that feeds both lights via separate fuses. The relay is operated by an output of the body control module.
 
hi thanks for reply any idea which relay and its position? and how to diagnose lack of signal from module? thanks again
 
I have attached the schematic for main beam. The relay is T02 in the cab fuse box. Pin 85 of the relay is the coil which gets ignition fed supply, the negative switching signal comes from the body computer on relay pin 86. The lamp supply is from the battery via a mega fuse on the battery + terminal to relay pin 30. When the relay is operated the supply is fed to each lamp via its own fuse from relay pin 87
 

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I have attached the schematic showing the switch to body computer set up. [H005 in the drawing]. It is a single pair of wires with different resistor combinations for each switch position. When the lights are first switched on the default to dipped beams and it need the main beam to be operated to select them. As dipped beam is working and you have changed the stalk I suspect the fault is further on.

The Body Control Module outputs a negative when main beam is selected on the wire which goes to relay T02 contact 86.
 

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hi thanks again not had chance to investigate any further but, when I turned off ignition last night the engine carried on running all dash lights went out but engine kept running if you fiddle with key turning off and partially on again a few times I goes off but engine management light pops up do you think both faults could be connected ie faulty ignition switch? :confused:
 
hi seems its likely the bcm then to prove this any idea how to test signal from stalk just to prove I havnt got two faulty ones, and then then test out of bcm ? and am I correct in thinking if I do replace with second hand the unit will need reprograming ?
 
Looking at the drawing of the stalk [H005] and the connection to it from the BCM it would appear that when main beam is selected that the two wires are shorted together. It would be relatively easy to disconnect the stalk and check the resistances when a) sidelights b) dipped and c) main beam are selected.

It appears from the link below that the headlamps are pin 4 negative and pin 6 switched negative on the stalk.
[sorry for any confusion but my cd will not show drawings anymore since I uprated to windows 10 - such is life]

To be honest I think in the end it will need connecting to the Fiat Examiner system where the stalk inputs can be set within the BCM and the outputs checked. There is a recent previous topic on dipped beams constantly on and that was the advise from someone who appeared more experienced than me .
https://www.fiatforum.com/ducato/464927-dipped-beam-headlamps-constantly.html
 

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You can connect to the BCM with Multiecuscan and actuate the lights directly, which will show whether the BCM is capable of sending the signal.
 
So I bought a second hand body control module and fitted and the lights all work as they should:) but realised before fitting that the original module code number 1349986080 the replacement one is 1359655080 they look and fit identical any body have a idea what the difference is ? and secondly the battery was nearly flat so was unable to try and start it , does any one know if the module needs reprograming due to immobiliser ? or other reason ? and if so where this can be done
many thanks for previous advice
 
So I bought a second hand body control module and fitted and the lights all work as they should:) but realised before fitting that the original module code number 1349986080 the replacement one is 1359655080 they look and fit identical any body have a idea what the difference is ? and secondly the battery was nearly flat so was unable to try and start it , does any one know if the module needs reprograming due to immobiliser ? or other reason ? and if so where this can be done
many thanks for previous advice

anybody ? please
 
Not a common question..

Why not just try it.. if it needes a relearn.. you can do that too.

Charlie

According to Fiat, the BCM is created at the factory for an individual vehicle, with all of the functions specific to that vehicle. I suspect you would need to have access to diagnostic software which can re-write the VIN in the BCM to that of the vehicle it is being fitted to, and then run through its configuration comparing the available and enabled functions against the vehicle it is intended to install it to. The latter can be done with MES via proxy-config and proxy-alignment, but it would rely on all the functions in the original BCM being available in the donor BCM.
 
And after all that is said and done it still won’t work because the key code is wrong! you can’t swap body computers!
 
This company could repair yours or they say provide a plug and play replacement. They appear knowledgeable. Perhaps they can help?
https://www.jccars.co.uk/Fiat/Fiat Diagnostcs.htm

ok It seems you can swap bcm! took a couple of attempts first donor was faulty but second one just fitted back and all as should be I have lights again. it did require sending off to get reprogramed from info on from original not a cheap fix but fixed(y)
 
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