Hi all. New problem just popped up this morning. 98 Firebird, turned on the lights, they came up with no problem, but only my driver's side lights are working. Low and high beams are inop. Replaced the low beam but no change. Parking light and fog lights work fine, but no headlight on the right only. Socket looks ok, not melted. Smacked the connector around a little since that can cause the dreaded "all 4 lights on" situation, but again, no change. Any help would be appreciated.
Formula757fixer
When you turn lights on, power goes to headlight change over switch and is fed to driver side lights. This is for low and high beams. The passenger side lights get power from splice S202 and S152. Both splices are on the driver side light wires. Also before going to passenger side lights, wires go through a connector. So make sure connector is good.
And make sure the black ground wire for passenger lights has a good ground.
I suggest downloading the 99 service manual for wiring diagram on page 8-47 I'd say download the 98 service manual, but for some reason it's missing the wiring diagram section.
So your first job is to get your multimeter out set to dc volts. Turn lights on. See if passenger lights get power on yellow and light green wires. You will have to toggle headlight change over switch to check low & high beam circuit. If no voltage at lights, go back to the connectors and check for battery voltage on the 2 wires there.
If no voltage at connectors, you will have to go to driver side of car and find splice S202 & S152. Check for battery power at splice. Since driver side lights work, the splice would have to be the problem.
So what you are looking for is where battery power disappears from splices on driver side lights to passenger side lights. This is assuming the black ground wire checked out as OK earlier. If you have battery power at lights and lights don't work, then black ground wire is suspect.
If no ground to passenger lights, lights won't work even with battery power at lights. So in this case, turn light off, disconnect battery cable. Disconnect connector at passenger lights. Follow ground wire to where it grounds to car body. Disconnect ground wire. Set multimeter to resistance and check ground wire for continuity. If bad, replace ground wire. If good, try cleaning the place where ground wire connects to car body.
Starting on page 8-72 is the component location chart to help you find ground G105, splices S202, S152, connectors, etc.
And make sure the black ground wire for passenger lights has a good ground.
I suggest downloading the 99 service manual for wiring diagram on page 8-47 I'd say download the 98 service manual, but for some reason it's missing the wiring diagram section.
So your first job is to get your multimeter out set to dc volts. Turn lights on. See if passenger lights get power on yellow and light green wires. You will have to toggle headlight change over switch to check low & high beam circuit. If no voltage at lights, go back to the connectors and check for battery voltage on the 2 wires there.
If no voltage at connectors, you will have to go to driver side of car and find splice S202 & S152. Check for battery power at splice. Since driver side lights work, the splice would have to be the problem.
So what you are looking for is where battery power disappears from splices on driver side lights to passenger side lights. This is assuming the black ground wire checked out as OK earlier. If you have battery power at lights and lights don't work, then black ground wire is suspect.
If no ground to passenger lights, lights won't work even with battery power at lights. So in this case, turn light off, disconnect battery cable. Disconnect connector at passenger lights. Follow ground wire to where it grounds to car body. Disconnect ground wire. Set multimeter to resistance and check ground wire for continuity. If bad, replace ground wire. If good, try cleaning the place where ground wire connects to car body.
Starting on page 8-72 is the component location chart to help you find ground G105, splices S202, S152, connectors, etc.
Turns out it was the connector, yet again, right behind the passenger headlight. Squeezed it around some more and poof low beam came on. Did it again for the high beam and it finally popped on. Don't know what it is about that particular connector but it seems to be a "problem area" for my car at least as far as the headlights are concerned. Fortunately it doesn't happen often. Thank you again for your great description though, Im gonna write all that down for the future!
The connector is ac delco pt1251 and available online, had to replace the one on my driver side, the pins rusted off
So I had a problem with the right (starboard 
headlight as well. Was dim. Turned out it was the connector. I had to bend the prongs on the lamp to fit tightly in the connector. No troubles since.
headlight as well. Was dim. Turned out it was the connector. I had to bend the prongs on the lamp to fit tightly in the connector. No troubles since.-
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