Technical Dipped beam lights going off

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Technical Dipped beam lights going off

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Does anyone know where the Body Control Module is on an 08 Adria Ducato 2.3, my motorhome failed MOT today as the dipped beam lights kept turning off.
I have read the thread on the 08 X250 explaining that the switch stalk is resistive and that the BCM was at fault.
 
Hi

Under the lower dash (behind a small screwed panel) on the UK driver's side is a Fuse/Relay/Junction Unit with a number of multi-way connectors. Immediately behind this is the Body Computer, with the bottom part showing where the OBD socket shows. These two items are normally removed as one, then they can be separated on the bench (they join together via a multi-way plug and socket).

Removal involves taking off some of the dashboard lower trim to give room for access, then undoing a few small bolts and a handful of multi-way connectors.

The switch stalks contain a number of resistors, the BCM can interpret the resistance value and thereby determine the stalk position. It's done this way to save on the number of wires needed. Any poor connection could upset the operation of this.

Another possibility is that you have a failed/failing or incorrect wattage dipped beam bulb, as the current is monitored by the BCM and if it is outside limits it may turn off the lights. A momentary short circuit of the dipped beam wiring (e.g. chafing loom) would have the same effect. Failure of the BCM itself is rare unless it has been subjected to water.
 

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  • X250 Fuse Relay and BCM.jpg
    X250 Fuse Relay and BCM.jpg
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Hi

Under the lower dash (behind a small screwed panel) on the UK driver's side is a Fuse/Relay/Junction Unit with a number of multi-way connectors. Immediately behind this is the Body Computer, with the bottom part showing where the OBD socket shows. These two items are normally removed as one, then they can be separated on the bench (they join together via a multi-way plug and socket).

Removal involves taking off some of the dashboard lower trim to give room for access, then undoing a few small bolts and a handful of multi-way connectors.

The switch stalks contain a number of resistors, the BCM can interpret the resistance value and thereby determine the stalk position. It's done this way to save on the number of wires needed. Any poor connection could upset the operation of this.

Another possibility is that you have a failed/failing or incorrect wattage dipped beam bulb, as the current is monitored by the BCM and if it is outside limits it may turn off the lights. A momentary short circuit of the dipped beam wiring (e.g. chafing loom) would have the same effect. Failure of the BCM itself is rare unless it has been subjected to water.
Thanks Athony for this knowledgeable and concise reply and so soon. This will help me a lot this morning.
 
Is it possible one of the headlamp adjuster motors is causing the dipped headlights shutdown? After getting some drawings this afternoon I now notice both motors are fed from the left hand light output.
 
Hi again.

I have now had a more detailed look at the Elearn diagrams for a 2008 van.

The headlamp height adjustment motors do indeed share a supply (via fuse F13) with the LH dip beam, so they will only operate when the dip beam is on.

For this age of van, the Dip and Main beam headlamps are controlled by relays, but there is NO current monitoring by the BCM, so ignore my previous comment about faulty bulbs etc. This also means that although an abnormal drain from the adjustment motors could blow F13 and leave you with one dipped headlight, it wouldn't cause both to be automatically be shut down by the BCM.

The finger of suspicion is pointing to the headlamp switch (stalk). If this is intermittently giving the wrong resistance value, this could be interpreted by the BCM as a command to switch lights off. Maximum resistance corresponds to "lights off", so an open circuit would also give this condition. The "active low" drive to the dipped beam relay will then be lost, the relay will open and both dipped beams will lose supply.

I don't have data for the various resistor values in the stalk, but if you unplug its connector and measure with an ohmmeter between pins 4 and 7 of the stalk I would expect to see for example 3000 ohms for OFF, 2000 ohms for SIDE, 1000 ohms for DIP and zero ohms for MAIN. These values should be "solid" i.e. no wavering. If this test is OK, I suggest replacing the stalk connector and repeating the resistance test at the BCM connector (unplugged from the BCM) so that the two stalk-to-BCM wires are included
 

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  • X250 Headlamps Dipped Beam.jpg
    X250 Headlamps Dipped Beam.jpg
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  • X250 Headlamps Height Adjustment Motors.jpg
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  • X250 Headlamps Main Beam.jpg
    X250 Headlamps Main Beam.jpg
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Hi again.

I have now had a more detailed look at the Elearn diagrams for a 2008 van.

The headlamp height adjustment motors do indeed share a supply (via fuse F13) with the LH dip beam, so they will only operate when the dip beam is on.

For this age of van, the Dip and Main beam headlamps are controlled by relays, but there is NO current monitoring by the BCM, so ignore my previous comment about faulty bulbs etc. This also means that although an abnormal drain from the adjustment motors could blow F13 and leave you with one dipped headlight, it wouldn't cause both to be automatically be shut down by the BCM.

The finger of suspicion is pointing to the headlamp switch (stalk). If this is intermittently giving the wrong resistance value, this could be interpreted by the BCM as a command to switch lights off. Maximum resistance corresponds to "lights off", so an open circuit would also give this condition. The "active low" drive to the dipped beam relay will then be lost, the relay will open and both dipped beams will lose supply.

I don't have data for the various resistor values in the stalk, but if you unplug its connector and measure with an ohmmeter between pins 4 and 7 of the stalk I would expect to see for example 3000 ohms for OFF, 2000 ohms for SIDE, 1000 ohms for DIP and zero ohms for MAIN. These values should be "solid" i.e. no wavering. If this test is OK, I suggest replacing the stalk connector and repeating the resistance test at the BCM connector (unplugged from the BCM) so that the two stalk-to-BCM wires are included
Cheers again Anthony for your time to give me the detailed reply. The only doubt I've got with suspecting the stalk switch is that when I turn on my dipped beam the indicator on the dash turns on and stays on even when the lights go off suggesting that the input from the stalk switch is correct.
It's kind of looking like I'm one of the rare unlucky ones with a faulty body control module.
 
Cheers again Anthony for your time to give me the detailed reply. The only doubt I've got with suspecting the stalk switch is that when I turn on my dipped beam the indicator on the dash turns on and stays on even when the lights go off suggesting that the input from the stalk switch is correct.
It's kind of looking like I'm one of the rare unlucky ones with a faulty body control module.
If I go down the route of buying a used Body Control module will it need to be reprogrammed I.e. the central locking?
 
I think that the central locking would be the least of your worries. It is my understanding that the BCM covers the role performed by the code receiver in earlier models. If I am correct, a used BCM will not be programmed to recognise your keys. In this situation the you will get the dreaded padlock symbol illuminated, and the engine will not start.

To confirm your suspicion of a faulty BCM, is it possible to monitor the output at relayT01, either by touch (hold a finger on the relay) the relay, or by removing it and monitoring the BCM output on terminal 86, to with a meter connected to +12V?

I am always sceptical when a relay is the first suspect, but failures are not impossible, so worth eliminating by substitution.
 
I think that the central locking would be the least of your worries. It is my understanding that the BCM covers the role performed by the code receiver in earlier models. If I am correct, a used BCM will not be programmed to recognise your keys. In this situation the you will get the dreaded padlock symbol illuminated, and the engine will not start.

To confirm your suspicion of a faulty BCM, is it possible to monitor the output at relayT01, either by touch (hold a finger on the relay) the relay, or by removing it and monitoring the BCM output on terminal 86, to with a meter connected to +12V?

I am always sceptical when a relay is the first suspect, but failures are not impossible, so worth eliminating by substitution.
Hi Comminicator, many thanks for your reply to the used BCM programming issue but I have been assured by the company who do it that it will recognise my keys as I have the original code for the keys. I also did test the BCM output to terminal 86 of T01 with multimeter which showed a very low and falling voltage. Will let you all know how it goes after I receive the used BCM and then send them both for programming.
 
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