Headlight Fullbeam Problem

[ukflyboy]

Hey folks, I've given up trying to solve my idle issue for the time being and just get it MOTed with last years work around. Went out to give it a function test and noticed something dodgy with the lights; when in normal beam the headlamps work fine, go to fullbeam and the RHS just turns off the main bulb completely (the little parklight still works). I swapped the bulbs around and the RHS still goes dark when on fullbeam (not ideal when you want things to be BRIGHTER!), so it isn't a blown bulb!

Any ideas? Is it likely to be a connector somewhere or a relay or something?

Guess I wont be getting the car MOTed tomorrow!

[Alan461]

First things to check are the rubbish white plastic connectors to the lights near the radiator

[v8s4me]

As above. Probably a dodgy earth.

[tvrgit]

v8s4me said:

As above. Probably a dodgy earth.

Unlikely. Main beam and dipped beam filaments share the same earth.

Agree it's probably that connector though - they are rubbish.

[phillpot]

yeah, total rubbish.... fancy using a connector that only lasts 25 years

[v8s4me]

tvrgit said:

...Unlikely. Main beam and dipped beam filaments share the same earth....

They may well share the same earth once the earths from both sides come together in the loom; but there's a lot of places for failure before then.

When I did my re-furb back in 2010 I tried replacing the original connectors with whizzy new waterproof ones. These turned out to be worse than the original ones so I had to re-fit those. This, and carefully cutting back the individual wires trying to find some clean un-corroded copper to solder to, took a total of 13, yes 13, hours!

The best solution I've seen is Phillpot's and one day I'll do that, but until then, as long as the original ones carry on working, I'm leaving them alone!

[tvrgit]

v8s4me said:

tvrgit said:

...Unlikely. Main beam and dipped beam filaments share the same earth....

They may well share the same earth once the earths from both sides come together in the loom; but there's a lot of places for failure before then.

When I did my re-furb back in 2010 I tried replacing the original connectors with whizzy new waterproof ones. These turned out to be worse than the original ones so I had to re-fit those. This, and carefully cutting back the individual wires trying to find some clean un-corroded copper to solder to, took a total of 13, yes 13, hours!

The best solution I've seen is Phillpot's and one day I'll do that, but until then, as long as the original ones carry on working, I'm leaving them alone!

The point is that each headlight bulb has 2 filaments and 3 wires - main beam feed, dipped beam feed, and one earth. So if dip beam on that side is working, that earth must be working as well, so it's either the main beam feed or the filament inside the bulb. He's swapped the bulbs but the problem didn't move, so it can only be the main beam feed on that side.

Which brings us back to that connector... Philpott you're lucky if yours lasted 25 years, I had to change mine years ago after my own impending-MOT-induced lights unreliability issues. After a temporary MOT friendly botch, I used those waterproof connectors (sureseal I think) and while they were fiddly to install, it wasn't that difficult once you got the hang of the first 1 or 2 wire connections, and had drawn a diagram (before you cut the wires apart!) of what wire connected to which.

Edited by tvrgit on Friday 8th April 09:53

[Top Gear TVR]

Main beam supply on that side. I'd stick main beam on and get tracing with your tester. I have one that makes a nice buzzing noise which makes life easier.

They share the same supply (left and right) from memory so its not going to be too much work to find a break / damage etc

[ukflyboy]

Must have been the connector. Ripped all the insulation tape off, cleaned it with contact cleaner, tested the connections either side with the multimeter and now it seems to be working fine.

Noticed while I was there that the headlamps are different output so bought some nice new Philips Xtreme vision ones off Amazon to stick in next week. Dunno why considering I never drive it at night!

Thanks for your help once again.