[1974SD455]

I replaced all four headlight bulbs after 3 of them ceased to work. After this replacement, I notice that the two outboard bulbs light up when on low beam, which I think should be normal.
When I switch to high beam, only the two inboard bulbs are lighting.
I am looking at the factory shop manual, and it seems like all 4 bulbs should be lighting when on high beam.
Is this correct?

If is not correct, has anyone else had this issue and what was done to fix it?
It is the original front wiring harness.

Thanks

[leeklm]

All four of mine light up on bright. I would suggest taking aook at the low/hi beam switch as the potential culprit.

Sent from my SM-G965U using Tapatalk

[68tpls400]

All four should be on when high beams are on. There must be a switch issue like Lee states.

[OG68]

Do the outboard headlights have three terminals?

[68tpls400]

Yes, the outer lights are low beam. They have three contacts, so they are on low, and high beam. The high beams only have two contacts, for high beam only.

[1974SD455]

Thanks guys. Yes, the outboard ones are three terminal. I will investigate the dimmer switch more today. I appreciate your help. 👍🏼

[OG68]

Take a look at the sockets behind the outer bulbs. Since the inner headlights are lighting up that means the switch is working. IIRC the splice for the inner high beams is at the outer low beam sockets.

[1974SD455]

I wanted to thank you guys again for your input. I was able to get my headlights working correctly this past weekend. It turns out that one of the new low beam bulbs was inop on high beam side. When I checked it with an oh meter, that element was open. I don’t understand how that would have caused what was going on to happen, but when I replaced that bulb, everything worked normal.

Cheers!