Online 1996 gmc yukon headlight schematic? free?

Drl only work in daytime not at night ???? Daytime running lamps are only suppose to work in day light hours . Low beam & high beams ? none of these work at night ?
Headlamps
The headlamps may be turned on in two different ways. First, when the driver places the headlamp switch in the HEADLAMP position, for normal operation. Second, with the headlamp switch placed in the AUTO position, for automatic lamp control (ALC). During ALC the headlamps will be in day time running lamp (DRL) operation in daylight conditions, or headlamp operation in low light conditions.
Headlamp ON/OFF control is determined by the body control module (BCM) by a signal on the headlamp switch on input circuit when the headlamp switch is in the HEAD position. When the headlamp switch is in the AUTO position, the BCM determines headlamps ON/OFF by the voltage from the ambient light sensor.
If the headlight switch is left in the ON position, the inadvertent power control feature will turn off the headlights approximately 10 minutes after the ignition switch is turned to the OFF position. If the driver places the headlight switch in the ON position after the ignition switch has been turned OFF, or if the ignition switch is in the ACCY position, the headlights will remain on until turned off or the battery runs dead.
The high beam indicator is illuminated when the instrument cluster receives a class 2 serial data message from the BCM that the high beams are illuminated.

Do you know what the BCM is ? Do you know what DTC'S - diagnostic trouble code's are ?
DTC B2575
When the body control module (BCM) senses a request for low beam headlamp illumination, the BCM sends a ground signal to the low beam headlamp relay through the headlamp low beam relay control circuit. The headlamp low beam relay will apply voltage to illuminate the headlamps.

Low and High Beams Headlamps Inoperative
Step
Action
Yes
No
Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics
Connector End View Reference: Lighting Systems Connector End Views or Body Control System Connector End Views in Body Control System.
1
Did you perform the Lighting System Diagnostic System Check?
YES - Go to Step 2
NO - Go to Diagnostic System Check - Lighting Systems
2
Place the headlamp switch in the ON position.
Change the dimmer switch position from the high to low beam positions several times.
YES - Does the headlamp system operate normally?
NO - Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems
Go to Step 3
3
Are both high and low beam headlamps inoperative?
YES - Go to Step 4
NO - Refer to Headlamps Inoperative - Low Beams or Headlamps Inoperative - High Beams
4
With a scan tool, observe the headlamp switch parameter.
Does the scan tool indicate ACTIVE? YES - Go to Step 7
NO - Go to Step 5
5
Connect a test lamp between the ground circuit of the headlamp switch connector and battery positive voltage.
Does the test lamp illuminate?
YES - Go to Step 6
NO - Go to Step 9
6
Test the headlamps switch headlamps on signal circuit of the headlamp switch for a high resistance, an open, or a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 12
Go to Step 8
7
Inspect for poor connections to the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 12
Go to Step 10
8
Inspect for poor connections to the headlamp switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 12
Go to Step 11
9
Repair the ground circuit of the headlamp switch.
Did you complete the repair?
Go to Step 12
--
10
Important: Perform the setup procedure for the body control module.
Replace the body control module. Refer to Body Control Module Replacement
Did you complete the replacement?
Go to Step 12
--
11
Replace the headlamp switch. Refer to Headlamp Switch Replacement
Did you complete the replacement?
Go to Step 12
--
12
Operate the system in order to verify the repair.
Did you correct the condition?
System OK
Go to Step 3

i would try replacing those bulbs,the headlights are dual filiment and can work on just high beam and not on low beam,so start there and replace your bulbs

Replace Relay #46 in the underhood fuse panel.

Either both bulbs are bad(I've seen it before) or your
dimmer/headlight switch is bad. If you can without pulling the bulb, pull plug from the light. If it's a 4 lamp system pull the low beam. Do this on the left side as the right feeds from the left. With a 12v test light, check for power. (with lo beam on) if you have
power, change the lamp, if you don't it's most likly
the dimmer switch at the steering collum.
Hope this helps Good luck

i had same p w 1996 gmc chgd bulb chgd switch checked wires in steering coloumfinmally went under dash where your left boot would be and wiggled a 3quarter by half inch relay and done it lite up all day of jackin 2sec fix

CHECK THE FUSES TO THE LIGHTS,CHECK THE HEADLIGHT SWITCH,SOMETIMES IT ACTS UP AND OR NEED TO CHANGE THE SWITCH, CHECK WIRES TO AND FROM THE LIGHTS

try taking your tilt steering(steeringwheel) and check which setting its on if the tilt steering is all the way down click it up to the next setting and then try your low beams if that still doesn't work try it one more click up you might have a short or pinched wire in your wheel colum

You headlight lamp have a diffuser mechanism which allows it to flip between the hight beam and low beam feature of the bulb. In fact, you high beam will function even if the low beam is not working.

I would recommend the purchase of the new headlight lamp. It would cost you you any where from $15.00 per unit to get a replacement lamp

Ok Guys Thanks I will check into the dimer switch first, But if it is the turn signal switch assembly with the high beam control on it, it will not be cheap, I think they run about 260.00 each.

Thank you for your input.

The headlight high/low beam switch assembly.96 Safari has the turn signal stem as the high/low beam switch.Removal of the steering wheel is necessary to get to the switch assembly for replacement.