Daylight running lights work but not headlight on left side

Bulbs are too big. Try bulb #194 in them.

try replacing the bulbs. They don't last forever.

Not sure I follow you.
Since 2000 most GM models use the dimmer switch and headlight switch to ground the lights instead of providing power.
The headlights get power from fuses for left and right, control is on the ground circuit side. So the ground wires go thru the dimmer then the headlight switch to complete the circuit.
The body control module grounds the headlight relay.

its a circut breaker for posission light, daylight, running light posissioned in front off your stearingwheel left side

both headlights?
many cars have 2 fuse one for left and one for right.
the operators guide shows fuses. fues 45 and 46 (HL left/right)
USA answer, if in Canada, with DRL light, do say so now....
(daylight running light option)
this car has headlight relay,
the HL switch ground the HL relay coil, the coil energizes and
12v power hits both head light fuses. and then lamps.
the lamps are grounded and glow.
the schematic is on alldata.com
easy tests. with any voltmeter.

did you blow a fuse when changing the light over?

Check fuses or relay..

head light switch replace.....hope it helps

Do you have tail ligts and side marker lights with drls on? if so you will have only dim headlights. Check fuses, I think the headlights are fused seperately.

Blue to headlights
White to Headlight switch
Brown to fuse hot
Red to ignition switch starter side
Orange to ignition switch keyed on
Green to ground