dragmop

2002 Cavalier coupe 2.2L auto

No low beam. High beam works fine (but seem dim). Put car in gear, green daytime running light (DRL) turns on then flashes for a few seconds, then off. Headlights also flash with this; and the relay at left of dash clicks.

Hoping for some insight or experience ...or maybe just some support
I searched here and via google.
If there is a thread or DIY that I missed, please feel free to shame me and point me in right direction.

I replaced both bulbs
I replaced the DRL relay
RT HDLP & LTHDLP fuses are good
The large plug under battery looks ok. Unplugged, terminals look ok. Some of the wires are chalky white where they exit the plug, but nothing appears corroded except the plastic plug housing (mainly the lock clip)

Still same behavior.

I removed cover from a DRL relay and plugged it in. If I manually hold the relay switch, low beams work and DRLs work.

I cleaned the battery ground at engine block and at battery tray
I cleaned the ground block that pigtails out from the headlight wire harness under battery tray (it was more nasty).

Now - still flashing behavior of DRL indicator and headlights ...but no high beam and no low beam. Switch lights on and left running light illuminates but right running light does not illuminate; and the right dash turn signal indicator illuminates when lights are switched on. (also left turn works but right turn is fast flash)

I checked at left running light socket and 12v while right running light socket is ~9v - but check right socket and battery ground, get 12v (so bad ground connection somewhere still).


My questions -
What is that ground block under the battery? Can I remove it and solder all the wires together? ...then connect it to chassis ground that is more easily accessed?

Do you think is worth it at this point to remove the large plug and solder all those wires? (I am thinking this is my next step)

Is there some other connection or ground etc that I should check?

Thank you

dragmop

So I am thinking either this issue is so beleaguered and beaten that you are all tired of explaining it to noobs; or I maybe stumped the community.

I am glad I did not spend any money on the headlamp bulbs and DRL relay I tested with - not the problem.
I am glad I did not tear into the large plug under the battery tray - it would have been a waste of time.

I found this video It provided the insight I was looking for and maybe more important, it provided a schematic.

No continuity between headlamp sockets and the plug on the blue return for ground wire (the one for low beam). So then my problem was in the front wire harness.
Taking it apart was not complex as it is mostly in open. Someone had fixed this problem before - poorly, with unsealed crimp connectors. While only the blue wire splice had failed, I replaced all the previous splices (4 total) with soldered and sealed connections.

The right running lamp was due to bad connection in the ground block I had cleaned the night before. Maybe I knocked it loose, maybe it was because the whole block was corroded. Either way, cleaned and repaired and good ground now.

All lights work as they should. Success!!

I also replaced a broken right front spring last night.
Next I will replace the left drive axle (torn CV boot, no symptoms yet, noticed when I was under to change oil)
...then figure out what is making a clunk in the rear brakes

(My daughter's car. She has been driving like this for ?months ...she did not hear the clunk (stereo too loud); she thought the popping when turning in parking lots, driveways, etc was just "something under the tire"; and my favorite - "yeah, lights don't work ...it's embarrassing because they flash, but I just use the brights so it's ok")