My left headlight went im so i just thought the bulb at gone out but after changing the bulb the light is still dim and when the brights are flashed the bulb completely turns off....please help

 

That would be the electrical systems/wiring forum. But it might also be good to list model, body style, and year along with that.

Different years and models have different 'quirks' in their components. In this case it sounds like a dirty connector somewhere, but it could also be a bad light switch.

 

That has all the earmarks of a bad ground.

 

Moved to appropriate forum

(Thanks, Dutch! )

 

I agree, it sounds like a bad ground. You should have three wires going to the bulb. One is high beam, one is lowbeam, and one of them is ground. Trace the wiring back and see if the ground has a good connection to the body.

 

My left headlight went dim on my 2001 F-150 so i just thought the bulb at gone out but after changing the bulb the light is still dim and when the brights are flashed the bulb completely turns off....please help

 

This is going to call for a point to point wire check, as what sounds like happened is one or more bad wires or connections.

I thought about it. Look at this, okay? The right hand light is fine, but the left is messing up. That seems to me like the wiring in the engine compartment because the switch supplies power to both equally.

Next thought - is your battery on the left side right next to that headlight? Reason I ask is because battery acid does horrible things to wires and connectors.

If the battery location is on target, pull the battery and clean everything up with a dish soap, baking soda, and water solution. Then hose everything off thoroughly and let it dry.

Next step - go in and take a real hard look at the wire connector on the headlight. Make SURE that it's clean. Then follow the wires back towards the harness. Look for any other connectors at all, and check them too. Also be on the lookout for scraped insulation, pinched wires, wires that look like they got caught and pulled by anything... Also be alert to sharp edged metal areas that might have cut or rubbed through the wiring.

You want to find some kind of evidence of obvious definite damage, and make certain that all your connectors are clean. Don't forget to check ground wire attachments to the body or frame - they have to be clean too! You can put vaseline on connections in the battery area to protect them from acid spills, it works like a champ and is inexpensive.

For twelve volts to turn that light on either in high or low beam it needs two things:
1) A path to get there (from the switch - to the front wiring harness - to the light)
2) A path to ground

If this doesn't bring some kind of result, we need the wiring diagram for the lighting circuit and a Volt/Ohm meter to read what's going on.

~Wolf

NOTES:
Headlight wiring normally comes into the E-Bay on one set of wires for both lights, and then is spliced from one headlight to the other. if the splice is bad it could cause this.

A quick fix might be to run new wire from the right headlight to the left using the same wire colors. You should avoid this if the answer can be found without carving up your wires.

Since the right light is working - we can rule out the charging circuit, the light switch, the fuse panel, the ignition switch, and so on. The problem is up front between one light and the other.

 

What happened with this?

I did find one interesting thing - there may be a pair of ten amp fuses (one for each high beam), and if one of them goes bad, it would also cause your problem. But not both high and low beam. I still think there is a bad wire, but look at the following schemo and see what you think: