95 Legacy, headlight problem

[Eurodevo]

Hello,

Please help.....

I have a 95 Legacy with a headlight electrical problem.

 

The left headlight has full power to the lamp. The right headlight keeps burning out.  Before it burns out it gets progressively dimmer over weeks.  In addition when I turn on the brights, the left lamp gets dimmer and the right lamp seems to get full power.  I checked the amps at each relay and I was getting 10.9-11.2.

I am thoroughly confused.

 

 

Thank you

Devin

[heartless]

have you checked grounds near the headlights?

[lmdew]

Check the connector on the lamp itself.  Lot's of times the connectors are loose and there is high resistance.

 

I've seen lots of them melted.

 

Check out, www.brighterideas.com  I bet you have a voltage drop in the system.  LoadPro will find the fault.

Edited November 18, 2013 by lmdew

[Fairtax4me]

Have you replaced the left headlamp bulb?

Most of the time a problem with the headlamps is due to a loose terminal in the connector.

 

 

have you checked grounds near the headlights?

There are no grounds near the headlamps on these. The lamps are grounded through the hi/lo dimmer switch in the dash.

[Eurodevo]

Hi.

I have replaced both headlamp bulbs and both plugs.  Over the course of the last year I have had to replace both plugs due to them over heating and melting.  Two days ago the right lamp looked like it exploded due to what appeared to be excessive heat.

 

I actually thought initially that there was to much power going to the lamps.  Now, it seems like there is a voltage drop on the right side.  I did not put my finger on each relay while someone turned on the switch, though I swapped right to left and they both seem to be working. ????

[lmdew]

Could be high resistance in the relay contacts.  Again checking the voltage under load at the headlight is the best way to figure out what's going on.

[Cougar]

If you are using bulbs that are a higher wattage than the original design was then that could be part of the problem. I assume the numbers you gave in your first post was really the voltage and not current draw. The voltage at that point is a little low if that is correct depending on if the battery voltage was at about 12.5 volts. Along with checking the voltage getting to the bulb itself it might be a good idea to check the voltage drop on the return side of the bulb and the negative battery post while the light is on. You should have less than .5 volts across that ground connection.

[Fairtax4me]

This could be a wiring problem with the headlamp circuit.

With the lamps on check for voltage on all three wires with the headlamps on low, do the same with all three on high.

On low you should have 12v on two wires, and close to 0v on the third. (The third will be the low side ground wire).

On high there should be 12v on two of the wires (the low side ground being one of them), and close to 0v on the third. The third now being the high side ground.

 

Anything more than 1V on the ground side wires indicates a wiring or connection problem to ground. Corroded frayed or broken wiring, poor connection at the head lamp dimmer switch, poor contact in the dimmer switch, poor ground for the dimmer switch, or poor connection in the junction connector where the wiring comes through the firewall.

 

Measure battery voltage with the headlamps on lo and hi. If the feed wire voltage drops more than 1v lower than battery voltage there is a problem with the power feed circuit. Poor fuse connection, bad fuse, poor relay connection, high resistance in the relay contact, or corroded frayed or broken wire.

[Eurodevo]

Imdew, Cougar, and Fairtax4me thank you so much.  Looks like I need to get busy chasing down voltage.  Will follow your advice and hope I can scare something up.  If not I will let ya know what I find.

 

Thank you so much.