Headlight woes.

[EGGBEATER]

Hey there, having some headlight issues.

Tuesday my passenger side headlight went out, so of course I grab a new bulb and toss it in, and it doesn't light up all the way. Dim, and not coming all the way on. So, I figure maybe I got a bum bulb and get another, same issue. Started googling around, checked my underhood 10A fuses, all were fine. Wiggled the connector around, no change. Used a multi on the connector, and was getting about 5 volts and then it started dropping down on the green wire, the black and blue wires were like .004 volts I think. Checked it with car off, and car in accessory.

Thought maybe I had a bad ground, only one I can find that looks like it may go to it is a small wire (same size as the HL connector wires) that is white, and connects to the frame for the radiator on the drivers side. It looked fine, and the drivers side bulb has no issues so I didn't mess with it.

Any help would be appreciated. It worked fine before, now kaput.

Car Info:

2008 Toyota Yaris Hatch
All stock.

[ern-diz]

Sorry you're having trouble. I'm by no means an expert, but I do remember having a similar issue to yours years ago. It started happening after having a front end collision early in my car's life. The body shop that did the repairs used regular size fuses rather than the extra tiny fuses the car comes with from the factory. My headlights still worked, but because the fuses were larger than they were supposed to be, they would occasionally touch each other from vibration (the fuses install opposite of each other in the fuse box) and when they did, one of my headlights would dim. Swapping out the standard size fuses for the smaller ones solved the issue and it's never given me another problem.

I know you said you checked all fuses and they were good, but did you pull them out to confirm that they are the super small kind and haven't been replaced at some point with the larger, standard size fuses?

[EGGBEATER]

Yep they are the tiny bus fuses. Car has never been in a wreck.

[B.B._07]

The Yaris has the headlights on a ground side switched set, what that means is the black wire at the passenger side headlight should have +12V at all times. Test the black wire with one lead on the black wire and the other lead on the a good ground or the negative battery terminal. If you don't have at least 12V then swap the two headlight fuses around (the fuses can be partially blown which is hard to spot just by looking). If you're still getting less then 12V then you know it's a wiring problem between the fuse box and the headlight, if the dimness issue moved to the other headlight you know it's the fuses. The blue wire is the low beam ground, green wire is the high beam ground. If you have a solid 12V at the black wire and the pass. side headlight is still dim you know it's a ground issue.