electrical and ignition One H4 Headlight Too Dim

[Mitch_M]

So over the summer I upgraded to Hella H4 headlights. I noticed the other day that the driver's side headlight is about half as bright as the passenger side. I've checked the relays to make sure the connection is good, and checked where the actual light plugs in. Any ideas on what could cause this? I wouldn't think the bulb would already be going bad, but that could be it. TIA.

[MikeWooldridge]

Swap sides with the bulbs to determine where the fault is.

[bnam]

Swap the bulbs left to right to confirm bad bulb.

[jgerock]

+1 on the above advice, but please tell us what year your car is and if it has been modified with additional relays (if a Roundie).  You mention relays so I am guessing it is a 74-76.

[Mitch_M]

+1 on the above advice, but please tell us what year your car is and if it has been modified with additional relays (if a Roundie).  You mention relays so I am guessing it is a 74-76.

 

Sorry, it's a '72 tii. I read on here that it was safer to put in a relay when upgrading to H4's. I'll swap bulbs when my classes let out for the day and report back then.

[M3M3M3]

so you DID use relays to power them and new wiring from batt+ to lights?

[Mike87]

Also check the ground connections.

[Mike Self]

+ 1 on grounds.  Headlight grounds are a simple bolt/screw that's fastened to the body, in a location that's vulnerable to rust/corrosion.  Just trace the brown wire (brown wires are always grounds on 2002s) back to it's ground, then clean and reinstall.

 

mike

[Mitch_M]

Yes I used new relays. And I swapped the bulbs. Problem still persists, so I'll check the grounds tomorrow when it's light out. Hopefully that does it.

[Poon]

Also check the ground connections.

This for sure.

A bad ground increases resistance. As the resistance in the circuit increases you experience a higher voltage drop, and less current flows through the circuit.

[FunkyLaneO]

Also feel the wires leading to the bulb. resistance = heat, if they feel warm when the light is dim then you know which wire/connection  is the culprit. My guess is the ground wire but it could also be one of the new connections you made when you added in the relays.

[Mitch_M]

Worked on the lights today. First thing I did was check the ground. Y'all were right. Grounds were dirty. Cleaned them up and voila! Lights are bright like they should be. Thanks everyone!