Technical Dip beam light issue

[Jon450]

Evening All

First post on here hope someone can help.

I've got an 08 Ducato 2.3 multi jet engine, the issue is the dip beam lights, they work but after a few hours they turn off, turn them on again they just go straight off. Main and side lights are ok. Relays have been replaced,bulbs, fuse box is ok. Any ideas, been told it could be the body control module..... Does this control the lights?
Any help or ideas appreciated

Jon

 

[CDK]

The body computer causes all kinds of problems, but in this case I have doubts because for some reason the head lights aren't monitored by it. The little black box warns you even for a dead bulb in the side mirrors but ignores dip beam and main lights.
This sounds like a thermal issue, most likely in a relay but you say they have been replaced, so it must be a junction box or connector having high contact resistance and getting hot. The first place I'd look with an infrared thermometer is the wiring in the relay box.

 

[Jon450]

Hi
Thanks for the reply, yes relays and bulbs have been changed I agree it does sound like a heat issue. As they work for a few hours before failing. It's covered by a dealer warranty as its a motor home. Just trying to find info on the issue, as where driving across Europe in a month so need it sorted by then.
Are their other fuse boxes fitted I've found the one by the drivers right leg, and the one in the engine bay.

Thx Jon

 

[rayc]

If it is happening on both headlight units then I suspect the body computer or its wiring. They are separate circuits from the body computer.
What voltages are seen at the headlight unit when they fail?

 

[Jon450]

Bit confused so does the body computer control the lights or not. One says no one says yes??

 

[Jon450]

No idea of voltage at the lights but they don't work so I would assume nothing. Leave them for a while then they work.... Thinking as heat/ thermal issue???

 

[rayc]

The lights are switched via the body computer. The steering wheel stalk connects to the body computer and various resistor values are selected depending upon the function i.e. sidelights, dipped beams and main beam. This allows the stalk to connect to the body computer by a single pair of wires. The lamp clusters connect directly to the body computer.
Look at the circuit diagram in my earlier post.

As a matter of interest in the fault condition when you select dipped beam does the level position indicator come on in the dash display with the number selected and can you change it with the level control?

 

[Anthony489]

Hello Jon450. It's true that the body computer M001 controls the dipped headlights, but it does it indirectly by activating the coil of Relay T01 which is part of the junction unit under the dash B002. The connection between them is via Pin 8 of Connector Y on the body computer and Pin 8 of Connector X on the junction unit.

This means that the body computer only has to handle the small relay coil current. The larger current for the lamps themselves (about 8 Amps) flows through the contacts of Relay T01, where it splits in two and flows to the lamp clusters F010 and F011 via individual fuses F13 and F12 which are also housed in the Junction unit B002.

Since both your lights fail together, I would concentrate on checking Relay T01 and its socket, and the signal from Body Computer M001 to junction unit B002 on Pin 8 of their respective connectors, which should be +12 volts for lights off and a low voltage for lights on.
As far as I can tell, the body computer only controls the dipped headlights, it does not monitor their current to detect bulb failure.

One other thought is that there is a fault with the automatic light switching from the rain/dusk sensor in AUTO mode, but not many Ducatos are fitted with this.

 

[rayc]

Further to the above post; If the relay is removed and a link placed across contacts 30 & 87 the dipped beams should be on.

 

[CDK]

"One other thought is that there is a fault with the automatic light switching from the rain/dusk sensor in AUTO mode, but not many Ducatos are fitted with this."

Automatic lights implemented in the well known Fiat quality must be a real nightmare!

 

[Jon450]

No auto control on mine but thanks

 

[Jon450]

It does display the level indicator when working not check when in fault condition, or tried to adjust it.

 

[Jon450]

Thanks for all the info, the vehicle is under warranty still but the dealer has failed to fix it on the first attempt. So I'm after as much info as poss, to fire back at them.
When they do fail, if you turn them back on they just turn off straight away, and you can here the relay in the drivers fusebox clicking off as the lights go out, this maybe pointing to what controls the relay.

 

[rayc]

It should be simple at that stage to determine if positive voltage is still on relay pins 30 & 85. If so does taking pin 86 to negative switch the lights on?
If we knew whether in the fault condition when you select dipped beam does the level position indicator come on in the dash display with the number selected and can you change it with the level control? Knowing that would rule a problem with the light stalk in or out.

 

[Jon450]

Next time they fail I'll have to check, what does earthing it out prove, Earth fault?

 

[rayc]

Next time they fail I'll have to check, what does earthing it out prove, Earth fault?

Assuming you have positive voltage on relay pins 30 & 85 then applying negative to pin 86 should operate the relay and apply positive voltage to the dipped beams via Pin 87 and the two fuses F11 & F12. This is what the body computer should be doing via connectors X & Y pin 8.

 

[lm04]

Remove wheel and shroud from column. Pull connector from stalk (left hand connector) There is a cover over the top - pop this off and you will see the connections. On the far right the pin will have overheated/melted the connector. Clean up any melted plastic to prevent further fire risk and as a stop gap, and reinsert. You may need to add a tab of plastic to push the connector up to maintain a connection.

Replace the connector as soon as you can!!

 

[stevecampy]

SORRY to jump in i have this problem too my relay chatters and lights flash the tell tale light on dash is on and i can adjust height ok. please help dont quite understand the earth bit. it also put the eml on when relay chattered so buying a code reader to see whats going on there.and heater is all over the place very confusing

 

[rayc]

SORRY to jump in i have this problem too my relay chatters and lights flash the tell tale light on dash is on and i can adjust height ok. please help dont quite understand the earth bit. it also put the eml on when relay chattered so buying a code reader to see whats going on there.and heater is all over the place very confusing

Then it appears that part of the circuit, relay, fuse etc is failing under load. The relay operates, the lights flash, the relay drops out because of the fault and the cycle starts again. Some investigation of the relay contacts and fuse is required and if nothing obvious some work with a voltmeter.

 

[stevecampy]

I Had this problem on a stilo it was light switch on the stalk cleaned with switch cleaner all good for the last few days I Earthed the relay and all worked well so lead to the switch