Headlamp control malfunction

Ive changed the relay and the headlight switch on the dash .. still wont turn off headlights ? Just changing parts won't fix it , need to test . Hooking up a professional scan tool , one that can read codes in the BCM - body control module is the way to start to find the problem . Then familiarize yourself with how they work.

Headlamps
Major components of this system are the body control module (BCM), headlamp relay, beam select relay, ambient light sensor, headlamp and panel dimmer switch, turn signal/multifunction switch, park brake switch, and the low and high beam headlamps.
The headlamps may be turned ON in 2 different ways. First, when the driver places the headlamp switch in the ON position, normal operation occurs. Second, when the headlamp switch is placed in the AUTO position, automatic lamp control (ALC) operation occurs. During ALC control, the headlamps will be OFF in daylight conditions or in low/high beam operation in low light conditions.
The headlamp relay receives battery positive voltage directly from the battery. The BCM supplies a ground signal to the headlamp relay for normal headlight operation. The BCM also supplies voltage to the beam select relay coil for high beam headlight operation. When the driver places the headlamp switch in the ON position and the dimmer switch is in the low beam position, the headlamp relay supplies current flow through the left and right low beam headlamp fuses to both low and high beam headlamps. Both low beam headlights are grounded through the beam select relay. When activated, 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 G106. The BCM then energizes the beam select relay which switches the headlamp grounds from the low beam headlight bulbs to the high beam headlight bulbs illuminating 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.
The instrument panel cluster (IPC) illuminates the high beam indicator when the BCM detects that the high beams are requested. The IPC receives a class 2 message from the BCM requesting illumination.
The Headlamps On at Exit and Perimeter Lighting modes can be adjusted using the steering wheel controls to select the function as displayed in the driver information center (DIC). The Headlamps On at Exit selection will allow the driver to customize the period of time that the headlamps remain illuminated upon exiting the vehicle. This period can be adjusted from 0-180 seconds. The Perimeter Lighting feature allows the driver to select if they want the headlamps and backup lamps to illuminate when the door UNLOCK button on the key fob is activated. This feature can be turned ON or OFF by using the DIC steering wheel control buttons.

DTC B2575 Headlamp Control Circuit

Circuit Description
When the body control module (BCM) senses a request for headlamp or daytime running lamp (DRL) illumination, the BCM sends a ground signal to the headlamp relay through the low beam headlamp relay control circuit. The headlamp relay will illuminate the low beam headlamps.

Install a scan tool.
Turn ON the ignition, with the engine OFF.
With a scan tool, command the headlamps ON and OFF.
Does the headlamp relay turn ON and OFF with each command?

Do you know what bi-directional control means ? Need a professional scan tool to do these type of test .

DTC B2602: Daytime Running Lamp Control Circuit Low or Open
DTC B2603: Daytime Running Lamp Control Circuit High

Without this type of info. from service repair manual an using a scan tool your missing the big picture .

Could be any number of reasons why this happens . The headlamp switch , the dimmer switch the headlamp relay , the BCM - body control module , wiring , connections , ground etc..... Without testing no one on here could say for sure what's wrong . Do you know how to test electrical circuits ? Viewing wiring diagrams then using a DVOM - digital volt ohmmeter to test the headlamp electrical circuits . Possibly hooking up a scan tool an checking headlamp switch input data to the BCM an seeing if the BCM is energizing the headlamp relay .
Free wiring diagrams here http://www.bbbind.com/free-tsb/ 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 click on the blue links .

https://www.youtube.com/watch?v=SO-eKuhCOqc&t=125s

https://www.youtube.com/watch?v=YaYtCVBodpw&t=98s

Headlamps
You can use the headlamps two different ways.
• Place the headlamp switch in the HEAD position for normal operations.
• Place the headlamp Switch in the OFF position for automatic lamp control (ALC) operation. During ALC the low beam headlamps are on for daytime running lamp (DRL) operation in daylight conditions or low beam headlamps and exterior park lamps on in low light conditions.
The DRL/EXT Fuse in the top underhood junction block supplies battery positive voltage at all time to the coil side of DRL relay, left low and high beam headlamps. The EXT LTS Fuse in the top underhood junction block supplies battery positive voltage at all time to the right low and high beam headlamps.
For normal manual low beam operation when the headlamp switch is placed in the HEAD position, ground is applied from G203, through the low beam contacts in the headlamp switch to the body control module (BCM).
The BCM then applies a ground to the headlamp relay control circuit. This energizes the headlamp relay in the left I/P junction block allowing ground from G201 to be applied through the switched contacts of the headlamp relay, through low beam contacts in the headlamp dimmer switch then to the left and right low beam headlamps, illuminating them.
For high beam operation the headlamp dimmer switch is placed in the HIGH position, ground is then applied from G201 through the switched contacts of the headlamp relay, through high contacts of the headlamp dimmer switch to the left and right high beam headlamps, illuminating them.
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.
If the headlamp switch is left in the HEAD position, the inadvertent power control feature will turn off the headlamps after 10 minutes after you turn the ignition switch to the OFF position. If you place the headlamp switch in the head position after the ignition switch has been turned OFF, or if the ignition switch is in ACCY position, the headlamps will remain on until you turn them off or until the battery runs dead.

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

What code's ? # code's P0 what ? Any BCM - body control module code's ? Did you do diagnostic test's for said code's ? Do you know what a factroy diagnostic flow chart is ? Is the vehicle a 4X4 or 2X4 ? What engine ? Do you know what class 2 serial data bus is ? Do you have wiring diagrams ?
Headlamp ON/OFF control is determined by the body control module (BCM) by a signal on the headlamp switch headlamp on signal 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.

High Beams
The high beam headlamps receive voltage from the headlamp HI relay located in the underhood fuse block. The body control module (BCM) controls the relay on the headlamp high beam relay control circuit. High beam control is determined by a signal on the headlamp dimmer switch signal circuit from the multifunction switch. When the headlamp dimmer switch signal circuit is grounded, the BCM grounds the headlamp high beam relay control circuit, illuminating the high beam headlamps. The right and left high beam circuits are independent and are fused independently in the underhood fuse block. The right and left headlamps are grounded at G100 and G104.
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.
Low Beams
The low beam headlamps receive voltage from the headlamp LOW relay located in the underhood fuse block. The body control module (BCM) controls the relay on 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 headlamp dimmer switch signal circuit is open, the BCM grounds the headlamp low beam relay control circuit, illuminating the low beam headlamps. The right and left low beam circuits are independent and are fused independently in the underhood fuse block. The right and left headlamps are grounded at G100 and G104.

DTC B2645
The body control module (BCM) monitors the ambient light sensor signal circuit in order to determine if the daytime running lights (DRL) or the auto headlights (ALC) should be turned ON in the AUTO mode. When the BCM senses the ambient light sensor signal voltage is between 1.75-4.9 volts, either the DRL will be commanded ON or the ALC will be commanded ON depending upon the amount of light received by the sensor.

DTC B2645 Ambient Light Sensor Circuit

The headlamps may be turned ON in 2 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 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.

Low Beams - Standard
The low beam headlamps receive voltage from the headlamp low beam relay located in the underhood fuse block. The BCM controls the relay on 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 headlamp dimmer switch signal circuit is open, the BCM grounds the headlamp low beam relay control circuit, illuminating the low beam headlamps. The right and left low beam circuits are independent are fused independently in the underhood fuse block.


Do you know how to test electrical circuit's - relay's ? How to use a digital voltmeter ?

Headlamp relay stuck closed ,maybe. or BCM - body control module problem . Do you know how these systems work ? Headlamp switch is an input to the BCM , BCM energizes the headlamp relay to turn on headlamps .

The headlamps are controlled by the BCM - body control module , do you know what that is ? The headlamp switch is a input to the BCM ,the BCM energizes relays to turn on the headlmps , low beam relay , high beam relay , DRL relay . These relay's are PCB - printed circuit board relay's ( non - serviceable ) If found to be bad the whole under hood fuse box would need to be replaced .
Low Beam Headlamp Operation
The low beam headlamps may be turned ON in 3 different ways:
• When the headlamp switch in the HEAD position for normal operations
• When the headlamp switch is in the AUTO position, for automatic lamp control (ALC)
• When the headlamp switch is placed in the AUTO position, with the windshield wipers ON in daylight conditions, after a 6 second delay
Battery voltage is applied at all times to the coil and switch sides of the LOW BEAM PCB Relay located in the underhood fuse block. When the headlamp switch is placed in the HEAD position, ground from G202 is applied through headlamps ON switch signal circuit to the body control module (BCM), signaling the headlamps ON request. In response to this signal, the BCM applies ground through the headlamp low beam relay control circuit energizing the low beam relay. With the relay energized, battery voltage is applied through the switch side of the relay, the left and right low beam fuses, and the low beam supply voltage circuits illuminating the low beam headlamps. Ground for the left headlamp is provided at G101 and the right headlamp at G100.

Do you know what B codes are ? BCM - DTC'S - diagnostic trouble codes , need a factory scanner or professional one to view these codes , not autozone or advance etc....Having a qualified repair shop check your vehicle would be your best bet.

DTC B2575 00: Headlamp Control Circuit

Circuit/System Description
The vehicle headlamps are controlled by the body control module (BCM) based on inputs from the headlamp switch and the turn signal/multifunction switch. The headlamp switch has four positions: Off, Auto, Park, and Headlamps. The default headlamp switch position is Auto, in which the BCM uses the ambient light sensor to determine when headlamps are needed. The Off portion of the headlamp switch is a momentary switch which overrides the automatic headlamps and will turn off the vehicle headlamps. When in the Off position, the headlamp switch grounds the headlamp switch headlamps off signal circuit, prompting the BCM to turn off the headlamps. The Park position of the headlamp switch will only illuminate the vehicle parking lamps. The Headlamp position of the headlamp switch will illuminate both the parking lamps, as well has the headlamps. With the headlamp switch in the Headlamp position, the headlamp switch headlamps on signal circuit is grounded, prompting the BCM to turn on the headlamps, regardless of other factors such as ambient light.
The headlamp high beams are controlled through the flash to pass switch and the headlamp dimmer switch, both located in the turn signal/multifunction switch. The flash to pass switch is a momentary type switch, designed to illuminate the high beams as long as the switch is held. With the switch closed, the flash to pass switch signal circuit is grounded, prompting the BCM to turn on the high beam lamps. The headlamp dimmer switch allows the operator to select between full time high or low beam operation. Unlike the flash to pass switch, it is not a momentary switch. When the headlamp dimmer switch is in the high beam position, the headlamp dimmer switch high beam signal circuit is grounded. This prompts the BCM to turn on the high beam lamps.
The BCM controls the headlamps based on the inputs explained above. When a low beam request is received, the BCM grounds the headlamp low beam relay control circuit. This energizes the coil in the LOW BEAM PCB relay, causing the relay switch to close. This then applies B+ to both low beam headlamps through the LT LO BEAM and RT LO BEAM fuses, illuminating the low beam headlamps. When a high beam request is received, the BCM grounds the headlamp high beam relay control circuit. This energizes the coil in the HIGH BEAM PCB relay, causing the relay switch to close. This then applies B+ to both high beam headlamps through the LT HI BEAM and RT HI BEAM fuses, illuminating the high beam headlamps

Do you know anything about automotive electronics ? Electronic control modules .
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 GMLAN serial data message from the BCM that the high beams are illuminated.
High Beams
The high beam headlamps receive voltage from the headlamp high relay located in the underhood fuse block. The BCM controls the relay on the headlamp high beam relay control circuit. High beam control is determined by a signal on the headlamp dimmer switch signal circuit from the multifunction switch. When the headlamp dimmer switch signal circuit is grounded, the BCM grounds the headlamp high beam relay control circuit, illuminating the high beam headlamps. The right and left high beam circuits are independent and are fused independently in the underhood fuse block.
Low Beams - Standard
The low beam headlamps receive voltage from the headlamp low beam relay located in the underhood fuse block. The BCM controls the relay on 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 headlamp dimmer switch signal circuit is open, the BCM grounds the headlamp low beam relay control circuit, illuminating the low beam headlamps. The right and left low beam circuits are independent are fused independently in the underhood fuse block.

Hooking up a factory scan tool an checking DTC'S - diagnostic trouble codes would be the very first step in trouble shooting this problem .
DTC B257A 00: Headlamp Switch Input Signal Mismatch
DTC 2575 00: Headlamp Control Circuit

LAMPS/LIGHTING - EXTERIOR PT
HEADLAMP LEVELING MOTOR - EXPORT
REMOVAL
(1) Remove headlamp unit
(2) Disconnect headlamp levelling motor electrical
connector.
(3) Rotate levelling motor one quarter turn counter clockwise.
This will free levelling motor housing from
the headlamp unit.
(4) Pull levelling motor straight from headlamp
unit. Significant force will be required to unsnap
motor control arm from lens reflector.
NOTE: The headlamp levelling motor control arm is
snapped into the lens reflector mechanism very
securely. Use a firm, steady pull to disengage motor
arm from reflector.
(5) Remove levelling motor from headlamp unit.
INSTALLATION
(1) While holding headlamp reflector assembly
still, push levelling motor until control arm is fully
seated into reflector mechanism. An audible "snap"
will be heard.
(2) Push and rotate levelling motor one quarter
turn clockwise to lock motor to the headlamp unit.
(3) Connect headlamp levelling motor electrical
connector.
(4) Install headlamp unit in the vehicle Locksmith Buffalo Ny 24 Hour Locksmith in Buffalo Ny 716 249 2944

Do you know how to test automotive electrical circuits ?
When the headlamp switch is turned to the HEAD position, battery voltage is applied to the headlamp opening door actuator control module through CKT 103. The LH head lamp door opens when battery voltage is applied to the LH headlamp opening door assembly through CKT 576 and ground is applied to CKT 577. The RH headlamp door opens when battery voltage is applied to the RH headlamp opening door assembly through CKT 578 and ground is applied to CKT 579. When the headlamp switch is moved to the OFF position, battery voltage is applied to the headlamp opening door actuator control module through CKT 306. The LH headlamp door closes when battery voltage is applied to the LH headlamp opening door assembly through CKT 577 and ground is applied to CKT 576. The RH headlamp door closes when battery voltage is applied to the RH headlamp opening door assembly through CKT 579 and ground is applied to CKT 578. Battery voltage is constantly applied to the headlamp opening door actuator control module from the HDLP MOT L MiniFuse® #4 (CKT 2940) and from the HDLP MOT R, MiniFuse #3 (CKT 3040). The headlamp opening door actuator control module is grounded by CKT 150 through Splice Pack #100 to G102.

Headlamp Doors Do Not Close
Install a scan tool and go to the BCM input display.
Monitor the headlamp off switch status.
Turn the headlamps on and off.
Does the scan tool indicate the headlamp off switch inactive and active?
--
YES - Go to Step 4
NO - Go to Step 6
4
Disconnect the headlamp opening door actuator control module connector C1.
Connect a DMM from connector C1 terminal D to ground.
Measure resistance to ground of circuit 150.
Is resistance within the specified values?
0-2 ohms
YES - Go to Step 5
NO - Go to Step 9
5
Connect a test light from the headlamp opening door actuator control module connector C1 terminal C to ground.
Turn the headlamp switch off.
Does the test light illuminate?