Headlight high beam fault

I saw this question hanging around since yesterday, so thought I would take a crack at it. I remembered that Jeff has access to data where grounds are, so thought I would try. I see he has answered.

Jeff Armer Aug 18, 2023
It's not a ground issue, driver side headlamp grounds at same place (G201) underneath the dash .

Headlamps
The headlamps may be turned on 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 OFF position, for automatic lamp control (ALC). During ALC, the headlamps will be in day time running lamp (DRL) operation in daylight conditions, or low beam operation in low light conditions. The LH HDLP and RH HDLP fuses, supply battery positive voltage from the under hood junction block to the left and right headlamps. The circuit continues through both low and high beam lamps, then back to the under hood junction block. The low beam and high beam circuits continue to the headlamp switch. The low beam and high beam circuits also provide the body control module (BCM) with both low and high beam inputs. The headlamp switch includes the dimmer switch and the flash-to-pass switch. When the headlamp switch is placed in the HEADLAMP position a path to ground is provided. Ground is provided at G201. Depending on the position of the high/low beam switch, either the low or high beam circuit will now have power and ground.

G201
On the left side of the I/P, near the fuse block

I found this, as Jeff says, not a normal ground near the light unit because it is computer controlled.

What is the ground wire for the headlight on a 2000 Pontiac

JustAnswer https://www.justanswer.com > Pontiac Problems
Mar 21, 2017 - What is the ground wire for the headlight on a 2000 Pontiac Grand Am? It only has three wires. two blue and one red or pink.

1 answer · Top answer: Hi, my name is ***** ***** body control module controls the ground for the headlights, ...

..

https://www.fixya.com/cars/t8706315-2003_gmc_yukon_xl_denali_low_beam

Did you test the low beam electrical circuit using a volt meter ? Look at a wiring diagram to see what all is involved in turning the lights on ? Do you know how to test electrical circuits ?
Also reading service repair manual about the head lamps opp. would be a good thing to do .
Headlamps
The major common components of this system are the body control module (BCM), ambient light sensor, multifunction switch, park brake switch, and the headlamps.
The headlamps may be turned on in 2 different ways. First, when the driver places the headlamp switch in the HEADLAMP position, normal operation occurs. Second, with the headlamp switch is placed in the AUTO position, automatic lamp control (ALC) occurs. During ALC control, the headlamps will be in daytime running lamp (DRL) operation in daylight conditions, or low beam operation in low light conditions.
The low beam relay and high beam relay receive battery positive voltage directly from the battery through the HDM and COILS fuses in the underhood fuse block. The BCM supplies a ground signal to the low beam relay coil for automatic headlamp control and normal headlamp operation. The BCM also supplies ground to the high beam relay coil for high beam headlamp operation. When the driver places the headlamp switch in the HEADLAMP position and the dimmer switch is in the low beam position, the low beam relay energizes sending current flow through the left and right low beam headlamp fuses to both low beam headlamps. The dimmer switch sends a ground signal to the BCM in the high beam position and a momentary ground signal in the flash-to-Pass (FTP) position from G102 to deactivate the low beam headlights and activate the high beam headlights. With the headlights in the low beam position, the high beams may be momentarily turned on or flashed by activating the FTP portion of the switch.

Low Beams - Standard
The standard low beam headlamps receive voltage from the headlamp driver module located in the underhood fuse block. The body control module (BCM) controls the headlamp driver module with the headlamp low beam relay control circuit. Low beam control is determined by a signal on the headlamp dimmer switch signal circuit from the multifunction switch. When the headlamps are requested ON and the headlamp dimmer switch signal circuit is open, the BCM sends a pulse width modulated (PWM) ground signal though the headlamp low beam relay control circuit to the headlamp driver module which illuminates the low beam headlamps at a 100 percent intensity level. The right and left low beam circuits are independent and are fused separately in the underhood fuse block. The LOW HDLP-RT 10A fuse supplies voltage to the right low beam headlamp and the LOW HDLP-LT 10A fuse supplies voltage to the left low beam headlamp. The right and left headlamps are grounded at G103 and G107 respectively.

Your best bet mite be to have a qualified technician check it

Most total headlight failures are caused by a bad component like a fuse, relay, or module. Wiring problems can also cause both headlights to stop working. High beam headlights don't work or low beams don't work. If just one bulb fails to work in either high beam mode or low beam mode, it may be the bulb. Check your manual to find your headlamp relay.

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

Both the headlight switch and the BCM provide a ground, or control circuit, to the headlight relay coil circuit for manual or automatic headlamp operation. When you place the headlamp switch in the OFF position, and the ambient light sensor indicates low light conditions, the BCM energizes the headlamp relay for low beam operation. You may switch the headlights to high beam by pulling the dimmer switch handle toward you until the dimmer switch is activated. When the dimmer switch is placed in the HIGH position, the indicator lamp input to the BCM is pulled low. The BCM then sends a class 2 message to the instrument cluster in order to illuminate the high beam indicator lamp.
Low and High Beams Headlamps Inoperative ?
Replace the headlamp switch. Refer to Headlamp Switch Replacement .
Did you check the headlamp relay ? Location ,left instrument panel
Did

Not a fuse problem , same fuse power's low an high beams . Looking at wiring diagrams an using a DVOM - digital volt ohm meter to test the electrical circuit's is the way to find the problem . The light's staying on for 3 or 4 min's. is a function of the BCM - body control module ! Do you know anything about automotive electrical testing ? Do you know what a wiring diagram is an how to read one . Free wiring diagrams here http://www.bbbind.com/free_tsb.html Enter vehicle info. Year , make , model an engine size . Under system click on lighting ,then under subsystem click on headlamps .Click the search button then the blue link. get yourself a cheap DVOM an test the electrical circuit's , this is how electrical problems are solved .
Electric Testing Techniques You Need to Know
Basic Electricity for Service Techs Ohm law Current Flow Opens Shorts

Plus reading factory service repair info for how it should work would be a good idea .

Headlamps
The headlamps may be turned on 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 OFF position, for automatic lamp control (ALC). During ALC, the headlamps will be in day time running lamp (DRL) operation in daylight conditions, or low beam operation in low light conditions. The LH HDLPand RH HDLP fuses, supply battery positive voltage from the underhood junction block to the left and right headlamps. The circuit continues through both low and high beam lamps, then back to the underhood junction block. The low beam and high beam circuits continue to the headlamp switch. The low beam and high beam circuits also provide the body control module (BCM) with both low and high beam inputs. The headlamp switch includes the dimmer switch and the flash-to-pass switch. When the headlamp switch is placed in the HEADLAMP position a path to ground is provided. Ground is provided at G201. Depending on the position of the high/low beam switch, either the low or high beam circuit will now have power and ground.
The LH HDLP fuse in the underhood junction block, supplies battery positive voltage to the automatic lamp control (ALC) headlamp relay coil circuit. The ALC relay switch circuit is connected to the low beam circuit at the headlamp switch. When the headlamp switch is placed in the OFF position, the BCM will automatically turn on the low beams in low light conditions. The BCM energizes the ALC relay, closing the switch contacts and grounding the low beam circuit. Ground is provided at G201. With the headlights in the low beam position, the high beams may be momentarily turned on or flashed with the dimmer switch handle. The flash-to-pass feature is accomplished by pulling the dimmer switch handle toward the driver. The headlights may be switched to high beam with the opposite movement of the dimmer switch lever. When the headlamp dimmer switch handle is pulled toward the driver, the flash-to-pass switch closes grounding the high beam circuit. Ground is provided at G201. Both high beams will remain on until the driver releases the switch handle.
If the driver places the headlight switch in the HEADLAMP position , the headlights will remain on until turned off or the battery runs dead.
Do you know what a factory diagnostic trouble shooting chart is ?

Headlamps Inoperative - Low Beams

Step
Action
Yes
No
Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics
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 HEADLAMP position.
Place the headlamp dimmer switch in the LOW position.
Do the low beam headlamps illuminate?
YES - Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems
NO - Go to Step 3
3
Disconnect the turn/headlamp wiper switch assembly connector C2.
Connect a 15 amp fused jumper between the headlamp low beam signal circuit and a good ground.
Do the low beam headlamps illuminate?
YES - Go to Step 4
NO - Go to Step 5
4
Inspect for poor connections at the harness connector of the turn/headlamp wiper switch assembly. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
YES - Go to Step 7
NO - Go to Step 6
5
Repair an open or high resistance in the headlamp low beam signal circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
YES - Did you complete the repair?
NO - Go to Step 7
--
6
Replace the turn/headlamp wiper switch assembly. Refer to Multifunction Turn Signal Lever Replacement - On Vehicle in Steering Wheel and Column.
Did you complete the replacement?
Go to Step 7
--
7
Operate the system in order to verify the repair.
Did you correct the condition?
YES - System OK
NO - Go to Step 3

Is this both the high beams and low beams that do not work ?

If you checked all 3 fuses with a meter ( with the headlamp in Low position for both low beam fuses or in high for the high beam fuse ), the next items to test are the MFS ( MultiFunction Switch ) and the main headlamp switch ( test not look at it ).

The main headlamp test chart


The test chart for the MFS

The headlamps themselves will look identical. If you were to look at the beam pattern of the light, then it would be different. Your original headlights were designed to throw excess light to the passenger side of the road (I.E. away from oncoming cars). Now that driving directions are opposite in France, your old headlights would be throwing the excess light into the oncoming cars, blinding them). The new lights are designed to throw the light away from those oncoming cars.

The adjustment screws/nuts should be located either on the top of the headlamp assembly, behind the headlamp assembly, or near the frame rail by the radiator support.

You will have vertical adjustment screws for each independent beam (separate highs and separate lows, but will be same screw if highs and lows are the same bulb). You may also have additional horizontal adjustment screws as well

Park your car on a level ground 30 feet from a wall and measure the height from the ground to the bulb and mark on a wall (do this for highs beams and low beams if the bulbs are separate, if highs and lows are the same bulb, only do it for the lows)

For Low Beams: If the headlights read VOR, then aim the brightest part or cutoff part just below the mark on the wall. If it says VOL or nothing, aim them 2 inches below the mark on the wall.

For High Beams (if separate from low beams): Aim the headlight directly at the line you marked on the wall.

The headlamp circuit is rather simple. From the 15 amp RH headlamp fuse, there is a red w/yellow trace that goes to the RH high beam. Out of the 15 amp LH headlamp fuse, the wire going to the LH Hi beam is solid red. Both of these wires should have power when the headlamp relay is energized. The wires from the Hi Beam bulbs going back to the switch should both be red w/black trace. The wire going from the headlamp relay to power the 2 15 amp fuses is white. The headlamp switch applies a ground to illuminate either the Lo Beams or the Hi Beams.