full beam light on one side doesn't work

[sharkjazz]

If have headlights on dipped, both work, if turn on full beam, the left side hardly works at all, emits less light than if on dipped.

I was thinking was a bulb issue, but someone has told me sounds more like a wiring issue.

Van is due an MOT and was hoping to fix this myself to save some £££s

[CovKid]

Well, guess you could swap bulbs and see if the problem persists. If its still dim on the same side it could well be a poor earth on the earth crown under dash or a poor connecvtion at fusebox or on headlamp itself.

[fullsunian]

Sounds like a bad earth that. As above, check terminal on bulb bet its corroded...

[kevtherev]

yes bulb holder

[little.legs]

Mine was like this when I got it. Turned out to be bad earths on the crown and headlight wire into the fuse box. Cleaned emup and bobs your uncle...)

[sharkjazz]

Finally got round to having a look on this. The problem is that on full beam, the left main bulb does not light at all, just the sidelight bulb illuminates.

Took the light out and had a look, the terminal on the sidelight was corroded (but this is working fine). Cleaned it all up whilst was there anyway.

However, the terminal on the main bulb was all fine, no corrosion whatsoever.

I put the the right hand side light into the left side, and that too did not work on full beam, so is definitely something up with the wiring.

Which would point to:

Poor earth on the earth crown under dash or a poor connection at fusebox

With regards to this, can I just go poking around with these wires, or should the battery be disconnected first? Other safety measures.

**heads other to the wiki to find out what and where the earth crown fusebox are **

[AngeloEvs]

IIRC, headlights have a fuse inserted on one side of Main beam circuit, if fuse ruptures then you lose one main beam headlight and Main Beam LED stops working too.....will check on circuit later to tell you where fuse is and which side is fused.