Weird Headlight Issue

[Bill Jennings]

Hi All,
Checked headlight light night before and both worked fine.
Car just failed the annual safety check as the right hand side high beam was not working. Bought a new H4 bulb but discovered both filaments on the old bulb were fine when I removed it.
Then I noticed that the three pin socket had been cut down to two pins with the third connection being made with a crimped on spade terminal, so I bought a new three pin connector and fitted it being careful to connect the wires in the right places.
Now I have two weird issues.
1. It seems that both high and low beam is going to the same wire.
2. With bulb connected just by the wires hanging loose in headlamp bucket the bulb is bright, but when fully installed/ assembled into front of headlamp with front glass fitted to car bulb is dim?????
There are two grounds in there correct? One going to 3 pin socket and one to a spade terminal that goes to the plate that has the springs on it to secure the bulb.
All wires are separate in headlight bucket ie not touching or shorting to each other. I soldered my new connections and covered with shrink wrap tubing.
I get 12 v between either ground and the wire that is hot in either high or low beam mode.
Any ideas of what the fault is?
I can take pics when I get home after work.
Cheers
Bill

[Bill Jennings]

Humble Pie Time,
I fixed it.
The high beam filament in the bulb was blown.
The high beam fuse was blown.
I wired the new Plug in reverse. I had it facing the rear of the car when I connected it up!
Cheers
Bill

[Wayne 962]

FYI for future readers of this thread, dim bulbs are typically caused by grounding problems...

-Wayne