Lighting Issue

[IanA]

Here's one to test you before I go outside with the multimeter.
Driving through some very wet weather the other night, the dipped and main beams all became inop at the same time.
The sidelights all work, indicators/hazards all OK and I got home using the front foglights.
The main beam blue dashboard light works OK but nothing gets to the bulbs.
Thing is- I can't find any common connection, fuse or relay that would account for this.
My first test point will be the light switch...

 

[IanA]

Replaced the light switch with a known good one- no change.
I haven't tested the bulbs yet but how likely that all 4 filaments would blow at the same time?

 

[t-tony]

But you said there is no power to the bulbs?

Tony.

 

[IanA]

Only that they all went out at once. The bulbs are the next test candidates.

 

[Duncodin]

Unlikely that all bulbs fail at the same time.

I was wondering if the lights and high beam all share a common earth?

There's one earth bundle bolted to the left hand inner wing just behind the left hand headlight. Unlikely that it's come loose. May be corroded. But then I don't even know if that earrh serves the headlights. But looking for a common denominator is where I'd start. Err. I think

 

[IanA]

I've checked the earths and on this car (it's a Tribute re-body) they are shared with the sidelights and the fog lights which still work.

 

[Duncodin]

In my case (tribute 507) fog light connections below the bumper haven't been touched but the new headlights are mounted in the GRP bonnet a 'long' way away from their original position. GRP doesn't earth too well so there's new earth wires, power and earth, doing quite a journey through trunking around the engine bay to the new headlights.

I assume you did the rebody yourself in which case you'll know what connectors were used to route the headlight wires to the new ones and how the earth was handled.

 

[IanA]

Yes it was the bulbs. All four filaments blew at once. What are the chances!!!

As DC said " Unlikely that all bulbs fail at the same time ". That's what sent me off on another track.

They are H4s so two filaments per envelope.

 

[Ianmc]

All four filaments blew at once. What are the chances!!!

Some sort of power surge?

 

[Duncodin]

Yes it was the bulbs. All four filaments blew at once. What are the chances!!!

As DC said " Unlikely that all bulbs fail at the same time ". That's what sent me off on another track.

They are H4s so two filaments per envelope.

Down the other track? If it was me I'd still be down that other track. Never in a month of sundays would I have expected all 4 to pop at exactly the same time.

We live and learn.

 

[t-tony]

Had it a few times over the years, allbeit both main or both dip, not all 4.

Tony.