Lost both headlight low beams?

[Fearhoza]

The other week i lost my left hand side low beam on the sierra (85 SJ40 w/ 5K). Meaning to take a look at it some time soon, i left it for a few days.

Friday just gone, the other one has disappeared as well. It seemed to flash for a millisecond when i turned it on, then it disappeared. Just like a household filament globe will flash for a moment before it dies.

The headlights dont have globes, but the two filaments looks okay through the glass as far as i can see.

High beams still work, and parkers still work.

Checked all internal fuses, all fine.

There are two little black BOSCH 12v30w boxes just behind the right headlight. One clicks when high beams are activated, other clicks when turning on the lows. The one that clicks with the lows.. is it possible faulty? A wiring/ground issue? Or just unlucky to have to replace both headlights

[lay80n]

They are the relays, and the clicking means they are turning on. Check with a multi-metre the power and earth at hte headlight coneectors. If you have a good earth at each, 12V at one terminal for low, and 12V at the other terminal when high is on, its your headlights. Replace and your all good. If not you will have to check your wiring and fuses. Sounds like the low beam has blown in both sealed beam units though.

Layto....

[want33s]

Test each headlight with a couple of old bits of wire from battery. If your headlights work directly from the battery the problem is the relay or associated wiring or the headlight switch.

[Fearhoza]

just found my multimeter after a good few minutes of searching. havent used it since high school electronics. I cant even remember what to set it to, V~ (200,750) or V- (200m,2000m,20,200,1000)?

It's been aaaaaaages!

[da13ro]

Not 100% sure on this, but 20 would be right IMHO. Just make sure the leads are in the un-fused plugs or youll probably kill the fuse in it.

[Fearhoza]

Sorry about that, i figured it out. 20 was right.

There is ~12v for both high and low beams on each side. High beams work, lows don't.

Looks like i have to replace both of the sealed units :(

Is there anything from a donor car that would bolt in that has globes? Or is it off to the wreckers to get charged an ass full for two lights?

[nicbeer]

look for anything with rect lights. u can buy new from autoparts store for bout $20 each if u want.

[want33s]

If you have a multimeter you can test your existing lights for continuity without having to power them up. Use the OHMS resistance setting (200 or less). Some multimeters have an audible beep setting as well.

[Fearhoza]

okay now this just shits me.

bought two lights from the wreckers two days ago. Have used them once since then.

Get in the car tonight. Start her up. Switch on the lights, left on flickers for a second, then goes out.

.... There's no way i can have that bad luck.

Could it be something that is shorting them and causing them to blow?

[nicbeer]

Are they blown again?

test them with some spare wire direct to the batt.

maybe run a new circut to the lights. be good for volt drop anyway.

[crispy]

How much did they cost you from the wreckers, like said earlier they arent very expensive from places like repco or autobarn for a sealed beam.

You would think if there was a fault the fuse would blow before the headlight, unless someone has put in a bigger fuse in the past.

The relay lighting upgrade is the best lighting mod and theres a diagram around here somewhere