Headlights do not work

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 .

I would check the fuses first. Headlights are typically on a separate fuse then the parking lights. If the fuse is fine check and see if the Bulb is burnt out but it is rare for both lights to go out at the same time.

Dimmer switch faulty or possibly light switch itself, or thier connectors.

The problem will be due to a malfunctioning headlight dimmer switch and a dimmer switch connector. Also check the high beam connector.

Replace light switch assembly. Remenber some switches pull up to flash headlights and press down to change from low to high--press down again goes from high to low.

HEADLIGHTS NOT WORKING

It can be faulty headlight switch or issue with its wiring. Or its faulty head light fuse.

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To troubleshoot the issue i suggest you few help links with appropriate solution. So you can follow the test and confirm what exact problem is there in your case of headlights not working:-----

Click the link below: -----

All headlights not working?

http://repairhelpcenter.blogspot.com/2012/01/all-headlights-not-working.html

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• Working of Headlight switch?
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• Both headlight bulbs blow together?

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• Car headlight bulbs don't last long?

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2007 Dodge Caliber: Low Beam Headlight Not working

http://technoanswers.blogspot.in/2012/06/2007-dodge-caliber-low-beam-headlight.html

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2003 Toyota Camry: Headlights Work Intermittently?

http://technoanswers.blogspot.in/2012/04/2003-toyota-camry-headlights-work.html

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Chevy Tahoe: Low Beam Lamps are not working?

http://technoanswers.blogspot.in/2012/04/chevy-tahoe-low-beam-lamps-are-not.html

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2001 Chevrolet Tahoe: Headlights not coming ON?

http://technoanswers.blogspot.in/2012/04/2001-chevrolet-tahoe-headlights-not.html

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2004 Dodge Ram: High Beam Light is DIM?

http://technoanswers.blogspot.in/2012/04/2004-dodge-ram-high-beam-light-is-dim.html

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2001 Chevrolet Tahoe: Both Low Beam Lamps Not Working?

http://technoanswers.blogspot.in/2012/04/2001-chevrolet-tahoe-both-low-beam.html

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Low beam headlights Modification?

http://schematicsdiagram.blogspot.in/2012/04/low-beam-headlights-modification.html

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How to Replace a Headlight

http://schematicsdiagram.blogspot.com/2011/08/how-to-replace-headlight.html

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How to Replace a Headlight Bulb

http://schematicsdiagram.blogspot.com/2011/07/how-to-replace-headlight-bulb.html

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How to Replace a Headlight Switch

http://schematicsdiagram.blogspot.com/2011/07/how-to-replace-headlight-switch.html

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How to Replace a Headlight Assembly

http://schematicsdiagram.blogspot.com/2011/08/how-to-replace-headlight-assembly.html

How to Replace a Park Light Assembly

http://schematicsdiagram.blogspot.com/2011/08/how-to-replace-park-light-assembly.html

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Low beam headlights Modification?

http://schematicsdiagram.blogspot.in/2012/04/low-beam-headlights-modification.html

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Headlight Assembly Removal On Honda Accord

http://technoanswers.blogspot.in/2012/06/headlight-assembly-removal-on-honda.html

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Honda Headlight Assembly Removal
http://schematicsdiagram.blogspot.in/2012/06/honda-headlight-assembly-removal.html

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How to Replace a Headlight Door

http://schematicsdiagram.blogspot.com/2011/08/how-to-replace-headlight-door.html

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How to replace HID headlight bulbs for lexus 400h?

http://schematicsdiagram.blogspot.com/2012/01/how-to-replace-hid-headlight-bulbs-for.html

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These will help.

Thanks.

There is a relay that controls the headlights, volvo calls it a step relay. You will have to check that power is getting to this relay. If not, check all fuses and wiring. If power supply checks out ok, you may have to replace the relay. Let me know if you need any more info or a wiring diagram.

check the bulbs first and also the fuses theres a fuse for each side and for low and high beams, start there, good luck.

Replace the high beam switch, it is part of the multifunction switch.

The main/high beam relay/switch must be stuck on high presuming the high beam stalk selector does not operate. Probably needs replacement.