My passenger side headlight (low beam, not parker) started to play up the other day. It just wouldn't switch on at times and if I turn it on and off a few times it would come back on.

Bulbs are newish and not blown for sure and they are correct watts.

Now the passenger side headlight is not working at all. However the strange thing is if I turn on highbeam that bulb would light up. Its just not working when I switch to normal low beam headlight.

Checked all the fuses in the fuse box and they are all good. Does anyone knows what's going on?

Sounds like a crook bulb or a dodgy connector that plugs into the back of the bulb.

Take the connector off again and have a good look at the terminals. If there is any corrosion or other crap in there it will not be making a good electrical contact.

Make sure also that that the female spade terminals inside the plastic connector block have a bit of tension to them. So when you slide it back onto the globe there is a bit of resistance. A bit of careful work with a small screwdriver or a scriber will fix this.

Either a bulb (filament for the low beam) or poor connection somewhere. You can use a multi meter to check if you are getting 12v at the connectors in the headlights for low beam. You could also swap the bulbs from left to right to eliminate the bulbs as the issue.

I have the same thing, and I know it isn't bulb related for me as I swapped them.

Definitely a connector issue i guess but I haven't gone any further with mine, so if you do lease post up.

The connector on the back of the bulbs (at least on the TH/TJ) can become dodgy, the connectors can kinda erode presumably through a sort of electrolysis. I have had to replace one of mine, though in my case both LB and HB were affected since the dodgy connector was the common 12V+ terminal (double negative system: the separate filaments have common power with separate earths switched via a relay operated by the stalk). In your case it's probably the LB earth that's dodgy. Bulb filaments can also break without visible signs of blown-ness, simple way to test is swap with the driver's side bulb. If the problem swaps sides it's the bulb, otherwise it's (probably) the connector.

EDIT: I swapped the connector with one that looked good from Nick-A-Part Pick-A-Part, just cutting the wires and using crimpy joiners. This was about a year ago, so far no excessive heat at the joins and no further problems.

My bulbs on my ts were brand new, 3 weeks old, all of a sudden I had your problem, I had parkers and high beams but no low beams, I checked fuses, connections voltages everything, the only thing I didn't check was the bulbs, they'd both blown after 3 weeks usage

Is there a prize for winning this guessing competition?

Turn on low beam, tap the relevant relay with a smallish screwdriver. If the light comes on, it's the relay. If the light stays off, it's not the relay.

That's my guess, anyway.

Heres an odd polssiblility for you

I recently upgraded the globes in our triton (I know, different car, but still the same idea)

Took the original working globes out and fitted new ones no worries, fired them up for testing, driver side low beam wasnt working, looked at the globe, looked fine, checked connections, looked fine, refitted, tested again, still no low beam on driver side, okay I thought, swapped globes around and voila.....problem fixed......stunned in disbelief, I reversed them again, same problem surfaced, swapped again, problem went away

How Bizaare!

Strange, but true, every word!

You guys have been so helpful! Thanks for all the replies.

Yeah I'll check the connector first..and if that doesn't work I'll swap the bulbs. Will update after.

I've tried tapping the relay and nothing happened.

Theoretically (and I stress "theoretically" because car electrics can just be weird) if it was the relay it would affect both sides of the car, ie. both the outside lights. In fact, since the badly-named "LB" relay actually supplies power to both the LB and HB filaments of the outer lights it would also affect high beam on these lights (the so-called "HB" relay only powers the inner 'driving' lights). Double-negative lighting system: invented by sadists and still confusing backyard mechanics everywhere (including this one)!