Headlight Issues

I've been replacing parts on this truck with my son. Putting it back together and having headlight issues, no wiring was replaced and all lights worked before. Not sure if this matters but the gas tanks and bed are not on the truck. Driving lights all work in 1st position. When pulling the light knob to the headlight or second position the driver's headlight and parking light are much dimmer than the passenger headlight. When turning on the brights, the drivers side headlight and parking light are very dim. Also, when in the brights position the left turn signal indicator is illuminated on the dash and won't turn off. I've cleaned all the grounds, and cleaned the connectors at the lights with no luck. Not sure what my next steps should be.

That's definitely a ground issue imo. Two headlight grounds on each side of the core support. Make sure the ground from the firewall to the engine block is good. Then there should be a ground from the core support to the frame on the passenger side. Then your battery should be grounded to the engine block. Check your tail light grounds too.

Sounds like a ground issue in the headlight system. Could be a headlight switch/connector issue too possibly.

Agree with ground issue. And likely it’s something you removed. Since they worked before.

Appreciate your responses and will work on this again this week and provide an update. Again, the bed is not on the truck thus the taillights are not hooked up at this time, hoping that is not an issue to try and resolve the headlight problem. Could anyone also post pictures of the ground locations so I can make sure I have all of mine hooked up properly. Also not sure if this is relevant but my truck has a dual battery setup.

I can't say for sure but Id bet the tail lights are gonna need to be hooked up for the rest of the lights to work properly. When wiring or bulb issues arise on these trucks it always seems to make the lights act very strange.

If anything ground the tail light grounds and the check what it does after that.

Do a volt drop test. Put a volt meter on the headlight ground,ground the other end to the battery negative,whatever the volt meter reads is the amount of voltage you are dropping through the ground. If you aren't dropping a volt or more ground is not your problem do the same thing but headlight positive and battery positive,same thing,look your volt drop. If that is confusing,put a clip on a long chunk of wire,clip it to negative battery post,touch it to headlight negative,did the bulb get bright? Do the same thing on the hot side,did the bulb get bright.