bjamick

iTrader: (31)

Soo not a newbie but might be missing something here.

99 trans am. Seen my low beam headlight was out. So bought a new one and it didn’t work. Took it back after I made sure I had 12v at the connector and I had like 11.6v. Got a new bulb and put it in, and same problem.

So im completely lost here. 12v at the connector yet bulb doesn’t work??? Put the headlight straight to the battery and the light worked 🤔

any ideas here, or am I missing something.

98CayenneT/A

Bad ground

bjamick

iTrader: (31)

thats what I was thinking. Wouldn’t that mean I wouldn’t have 12v at the connector?

B52bombardier1

No. The 12 volt + side is one half of the circuit and the negative (ground) side is the other half of the circuit. The electrons that flow out one side of your headlight circuit return on the other side though they are . . . somewhat less energetic on the return trip.

Run a short length of 14 gauge wire as a temporary ground to the bad headlight socket ground lug. See if that fixes it. If yes, you know which side of the circuit is the offending aspect. Fix that. Use caution here about shorting things out. It won't hurt anything if you do except blow a headlight fuse.

Rick

wssix99

iTrader: (5)

It's not uncommon for the stock bulbs to be bad off the shelf. There was a bad batch of Sylvanias a few years ago. Particularly if you aren't getting these from a big box store that turns a lot of stock, this is not shocking.

I'd swap your left/right bulbs to be 100% sure.

bjamick

iTrader: (31)

thats why I hooked it directly to the battery. Just to rule that out. I’ll try and run a dedicated ground wire and see if that fixes it.

TheNutDriver

iTrader: (1)

If you are measuring 12v at the connector plug, the ground must be ok, unless you're using a chassis ground instead of the ground on the connector plug.

bjamick

iTrader: (31)

Yup I measured at the connector. Red on my multi meter to the yellow wire and black on the black. I get 11.6v

TheNutDriver

iTrader: (1)

This just happened to me on Friday - measured a healthy 12volt at the connector with it off and in my hand, but with it connected to the sealed beam terminals, the light wouldn’t turn on. Pulled the connector off again and found that just inside the plastic, the live wire was severed off to the point where it would only connect and show voltage in certain orientations, one of which was when holding it upright in my hand to test with my meter.

wssix99

iTrader: (5)

Sorry. I missed that. This also happens and has happened to me before. I'd still try swapping the bulbs (left to right) and see what happens.

Sometimes, the bulbs (out of the box) don't make good contact with the headlight connector or the headlight connector gets corroded. (Actually, these bulbs are in a very wet location so all of the connectors back there get really corroded.) You can try bending the bulb prongs inward slightly toward each other. This will have them make more solid contact.

If that fails, you may need a new connector/pigtail for the bulb.

If you are going to keep the car for a while, I highly recommend the LMC Truck upgrade. All these problems go away and the light from the bulbs is many times better: https://ls1tech.com/forums/stereo-el...ht-option.html

RevGTO

iTrader: (12)

I have had exactly this happen several times with my sons' cars. I do this and then tape up the connector to the bulb so it doesn't work loose.