Dim headlights, voltage problem?

[buck91]

On our 01 aurora the headlights are quite dim and yellow despite clean and clear lenses with fresh Philips extreme vision bulbs. Measure the voltage at the plug to be in the high 11 to low 12vdc range. Battery is remotely located in the truck and I believe there is a factory relay setup in place. What is the proper way to measure headlight bulb voltage? Any ideas for improving my situation with a major rewiring? I was thinking about adding a better ground but not sure how that would effect the oem relay?

 

[97prizm]

Chevy out the jeep wrangler forum there is a write up on this very issue. Typically this indicates a poor or dirty ground wire.

 

[wrcsixeight]

I was getting nearly 3 volts drop measured at h4 connector with the lights on.

I made up a new 12awg relayed harness and now it is about 0.2v drop. Quite a difference in output.

Daniel Stern has a specific procedure listed for measuring voltage drop in the HL circuit. I am not sure what the difference in his method is compared to taking readings right at the contacts on the connector itself

http://danielsternlighting.com/tech/relays/relays.html

 

[Shaman]

Do you have an underhood fuse block with a jumper and positive connection?

 

[BHopkins]

Originally Posted By: buck91
On our 01 aurora the headlights are quite dim and yellow despite clean and clear lenses with fresh Philips extreme vision bulbs. Measure the voltage at the plug to be in the high 11 to low 12vdc range. Battery is remotely located in the truck and I believe there is a factory relay setup in place. What is the proper way to measure headlight bulb voltage? Any ideas for improving my situation with a major rewiring? I was thinking about adding a better ground but not sure how that would effect the oem relay?


You said you were considering adding a better ground. How did the ground look when you checked it? Was it tight, and free of corrosion? If the answer to either is no, then undo the ground, clean up the attach point to bare metal and reattach.

 

[buck91]

I do not have a ground chart for the vehicle and have not had time to try to chase the harness yet.

 

[BHopkins]

Originally Posted By: buck91
I do not have a ground chart for the vehicle and have not had time to try to chase the harness yet.


It is usually pretty easy to find headlight grounds, particularly on GM cars. Just follow the lead from the back of the headlight to where the ground wire comes out of the corrugate. It usually is grounded to the frame only a few inches from there. GM likes to attach the ground to the frame right over the headlights, or sometimes to the inside of the wheel wells, right behind the headlights.

 

[Klutch9]

To the OP, this is a perfect excuse to make yourself a homemade headlight harness! All you need is a relay, some electrical connectors and/or solder, 12-gauge wire, corrugated plastic sheathing (optional, for appearance), and a basic knowledge of low-voltage DC circuitry. I made one myself last winter in a few hours, and it worked great! I still need to get around to making one for my van.

 

[Olas]

Here is a diagram of a relay'd headlight loom i made and used in my car.. shows H4's but the principle is the same no matter what lamp you use

http://i64.photobucket.com/albums/h199/the_smudger/NewImage.jpg

 

[Ken2]

Measure the voltage across the battery terminals with the engine running at a moderate rate (about 2000 rpm if you have a tach). It should be in the high 13+ range, maybe a bit higher. If the voltage is lower after the battery has time to fully charge, you have a charging system problem or a dying battery.

Measure from one headlight contact to the battery negative post with the lights turned on. If you see almost the same as the full battery voltage, you're on the positive contact. If you see much lower voltage than the battery voltage, you have a poor connection on the positive side.

If you see zero volts or very little voltage, you're on the negative contact and know you have an excellent ground connection. Of you see a couple of volts here, you know you have a poor ground connection.

If you have the poor ground connection and a simple cleaning and tightening doesn't help, a relay system can work around a lot of hard to trace problems.

 

[buck91]

Thanks Ken2, very concise. So this requires back probing the headlight connector (in other words, you parallel the DMM with the circuit)?