T6 Caravelle near side main beam out

[Wafu]

Hi all wise ones.
My current problem is as the title says. I have a 68 plate, Caravelle executive and have up grades the lights with THQ V3 lights some years ago. No problems until the other week or so. The V3 lights have LED main lights and standard Main beam H1’s fitted.

I noticed a little while back that when I put main beam on the ‘light out’ symbol came on on the dash, easy I thought, the main beam bulb has gone. Sure enough the near side didnt work so I changed the bulb. However the fault remained and every time I start the next journey and used the flash or put main beam on the symbol came one and I only had the off side working. I checked the vehicle main loom to THQ lights and I have 12v pos coming from the van to the back of the bulb. Is the black wire to earth or does it go via a sense feed (possible CAN bus)? I can’t find a wiring diagram on google so flying blind at the momen.

I have spoken to Chris at THQ and he has been honest and said that he is limited in his tech knowledge but has also said that it may be related to the tow bar (VW factory fit) or the reverse camera (I’ve fitted this into my standard head unit, with so far no problems)

Can any one advise possible problems that I can go to? I.E. where the OEM tow bar can be disconnected to remove for faultfinding?

Thanks in advance.

 

[roadtripper]

One of the benefits of VIP Membership is access to wiring diagrams, which may be of help.

You mention that main beam is both LED and H1?

If you did replace a H1 did it work? If so did you try another one? Sounds silly but I spent a weekend chasing a fault in the XC70 only to find that the brand new lamp was in fact duff.

 

[Wafu]

One of the benefits of VIP Membership is access to wiring diagrams, which may be of help.

Very good point and I’ll certainly look into this, thanks.

You mention that main beam is both LED and H1?

If you did replace a H1 did it work?

Apologies if it’s wasn‘t clear.
My Main Beam is a H1 standard halogen bulb.
My Driving headlights are the THQ LED replacements, recommend by THQ for their V3 lights.

I did replace the H1 with two separate bulbs, that I tested before and after trying them in the THQ lights, they went in serviceable and came out serviceable, the same fault occurred each time, no Main Beam light on the near side and a light out symbol on the dash.

 

[roadtripper]

Next check for me would be the socket and the wiring see if there are any faults or nick that might let in damp and corrosion.

As a left field thought try replacing both? Some of the lamp detection works by comparing the pairs of lamps to account for wiring etc.

 

[CJW]

Just a thought to explore: Did you have the THQ V3s fitted? Did they replace H4s or the dual H7s? If the former, has it been coded to keep the main beam lamps on when the full beam switches on? The line of thought being the resistance is not what the ECU is expecting when full beam applied. Easy way to check - do your main beam lamps stay on when you apply full beam?

 

[Wafu]

Just a thought to explore: Did you have the THQ V3s fitted? Did they replace H4s or the dual H7s? If the former, has it been coded to keep the main beam lamps on when the full beam switches on? The line of thought being the resistance is not what the ECU is expecting when full beam applied. Easy way to check - do your main beam lamps stay on when you apply full beam?

I have had the THQ lights for around three years now with no faults and the main beam working as you would expect. If memory serves it was a plug and play with the lights and so no re-coding was needed (something THQ say in their sales)

I think I’m looking at a chaffed wire or something similar, this weekend I’ll take the front bumper off and investigate more deeply.

 

[Wafu]

As a secondary thought, is the main beam on the canbus or is it straight to earth? I.E. can I just check continuity from the plug to a vehicle earth? I have 12vts to the back of the bulb.

 

[dubber36]

Have you still got your old headlights that you can plug in and check to see if they work? From memory, the plugs just about reach with the test headlights sat on top of the fitted ones.

 

[Wafu]

I’ll try that.

 

[Wafu]

Latest on this snag, after looking deeper and having all morning on this, I finally found a chaffed wire. In-line splice made and now it all works.

Thanks to the community for reaching out and giving their time to help.