Dim headlight

[caltanian]

Took off today and found that the passengers side headlight is dim. This is strange and sudden, as I have installed the relay upgrade as well as headlight upgrades, and have had no issue for almost a year.

Would love to hear some ideas on what this could be a result of.

[SteveJ]

Did you check your fuses?

[rcb280z]

Also check and make sure your relays aren't the issue. I had a similar situation and found my relay was not making good enough contact in the connector.

[Marty Rogan]

I had that issue once. I pulled the fuse, pinched the prongs together, so it held the fuse tighter. the problem went away.

Hope your problem is that simple.

Marty

[Montezuma]

Odd I have the same problem. I have to fix it; kinda embarassing having one dim headlight. I however do not have the upgrade yet.

[caltanian]

So went out with a power probe, and started doing a little seeking. Gave it a ground, and lo and behold its bright again. The wire must have just moved strangely, or something but that fixed it..

[Wade Nelson]

This is a classic voltage drop problem.

Turn on the headlights. Now measure the voltage across the battery. Should be 12.4-12.6 volts or so, engine off.

Now measure the voltage AT the headlight itself. Chances are you'll only see 11.5 or so.

So you're missing around .9Volts. That is a voltage "DROP"

The trick is to find where you're losing that voltage; in a dirty relay contact, at a poor ground, in a poor crimp. One of those is adding resistance to your circuit, and when the headlight current flows through it, well, V= IR, the resistance times the headlight current equals around .9 volts of "drop"

You can lose voltage on either the ground side OR the positive side of the headlight circuit.

Start by running a wire from battery ground directly to the headlight connector. Does your bulb suddenly get a lot brighter? Then you probably have a bad ground; paint underneath a ring terminal, whatever so your headlight isn't seeing zero volts like it should.

Next run a wire directly from battery plus (B+) to the headlight connector? Does it get brighter? Next, using your meter trace back through the relays, switches, connectors, fuses, till you find where the voltage is getting dropped.

A little corrosion, a very little resistance (as little as 1/10 of an ohm) and you can create a significant voltage drop that will make headlamps dim.

[TomoHawk]

Keep a few cans of DeOxit in the arsenal. It is used to remove oxidation from fuse panel clips, blade connectors, pin connections, switch contacts, etc. DeOxit 100 takes off the heavy oxidation, and DeOxit 5 is used to lubricate and maintain the contacts.