HEADLAMP ISSUE

Hi, i have 4 headlamp system on my 2014 t800 kenworth. so one is a low beam and the other highbeam on each of the sides. this is how it should work.....when you turn on your low beams ....low beams on the passenger and driver side go on...and if you turn on the highbeams than both the high and low beams turn on the passenger side and driver side.

The issue i have is when i turn on the low beam only the passenger side is on and when i turn on the highbeams than the low beam on the passenger side turns off and the low and high beam on the driver side is on. So when the low beam is on i am not getting any power to the driver side. i checked with multimeter and when the high beam is on i am not getting any power to the passenger side. This is what i have done so far:

1) i checked and replaced the headlights still the same issue.
2) checked the 8 fuses by the fire wall---they are good
3) replaced the lowbeam switch---still the same issue

What should i do next? is there a relay?

 

They have 8 fuses labeled chas node under the hood box. i have checked those they are fine. i cant seem to find the relay....so i dont know if it is run through a module. I am the original owner and haven't touched the wiring at all. i will look for any spot the harness is flexing. also out of the 8 fuses only two show power when the headlights are turned on. So does this mean the relay is not working as it should? i will try to get a wiring schematic.

 

Ok i will check that and get back to you guys. Thanks for the help.

 

Ok so i disconnected the lights and measured the volts. their are 3 wires going to head lights (one is for the ground, the second is for the high beam and the third is for the low beam. When the low beams are turned on the driver side, the low beam voltage varies from 0.5v to 3.0v but is steady unless you shake the wire harness and at one time read 12.67v and the high beam wire was reading 8.6v. And when the high beam is on the high beam wire reads 12.6v and lowbeam wire reads 0.5v and this stays steady regardless of shaking the wire.