Twin headlamp failure

Question edited for clarity.

Fuses 4 and 8, but there is also a relay involved.

Fuse Box Diagram Mercury Mountaineer (1997-2001)

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Here you will find fuse box diagrams of Mercury Mountaineer 1997, 1998, 1999, 2000 and 2001, get information about the location of the fuse panels inside ...

Mercury Mountaineer (1997 - 2001) - fuse box diagram

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Aug 11, 2018 - Mercury Mountaineer (1997 - 2001) - fuse box diagram. Year of production: 1997, 1998, 1999, 2000, 2001. Passenger compartment fuse panel.

Mountaineer » Fuse Diagram

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Fuse Box Diagram Mercury Mountaineer; engine 4.0 L Cologne V6 and 5.0 L Windsor V8 (1996, 1997, 1998, 1999, 2000, 2001)

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 .

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

Check voltage circuits. The ten amp fuses are for low beam. Turn on the headlamps, lo beam setting, use a test lite to check voltage on those two fuses. If no voltage may be problem with dimmer switch?

By "dipped" headlamps, do you mean the "low" beam headlamps? If so, the dimmer switch [located on the turn signal stalk] may be bad. Have you checked for power to the low beam wires at the headlamp electrical sockets? BMWs, unlike most cars, do have fuses for the headlamps, so yes, it is possible that those fuses have blown.

Both your low beam and your high beam is protected by the same fuse, so it makes sense that the fuse is OK if the high beam is working on the passenger side. There are 3 fuses for the headlamps. Fuse #13 in the Battery Junction Box (20 Amp). If this fuse is blown, the headlamp relay will not have any power and neither high nor low beam on either side will work (you will have no headlamps at all) Then there is Fuses #2 and #3 (15 Amp) in the Battery Junction Box. #2 goes to the left low and high beam and #3 goes to the right low and high beam.
The headlamp switch uses a SINGLE CIRCUIT to control BOTH sides at the same time, so if one side works, the switch cannot be the problem. The headlamp relay provides power for fuses #2 and #3 and we already ascertained that these fuses must have power since we have working lights on both sides, so the relay cannot be the problem. A replacement bulb has already been tried, so that pretty much leaves us with a bad lamp socket. (Most likely cause) or a bad connection at splice #S122, which is located in the main wiring harness near the breakout for the left headlamp. (RED/BLACK wire)

This care is basically a Cadillac but without the badging.
Look under the hood for the main fuse block and then look for the headlamp fuses.
All four headlamps have their own fuse.

Try checking your fuses. I've seen them blow when the light bulb goes. Hope this helps.

Daytime Running Lamps
The daytime running lamp (DRL) system is designed to turn the high beam headlamps on, with a reduced light output, and without illuminating the high beam indicator lamp in the instrument panel. You have a DRL Module.
The multifunction switch is the stalk on your column.

This is 96 F150 circuit. Don't have 94.


Symptom Chart, Headlamps HEADLAMPS Condition Possible Source Action

• Headlamps Inoperative

• Circuitry open/shorted.
• Damaged headlamp switch.
• Blown fuse.

• GO to Pinpoint Test A .

• Headlamps On Continuously

• Circuitry open/shorted.
• Damaged headlamp switch.

• GO to Pinpoint Test B .

• High Beams or Low Beams Inoperative

• Circuitry open/shorted.
• Damaged multi-function switch.

• GO to Pinpoint Test C .

• One High Beam or One Low Beam Headlamp Inoperative

• Circuitry open/shorted.
• Damaged connector.
• Headlamp bulb damaged.

• GO to Pinpoint Test D .

• Flash-to-Pass Inoperative

• Blown fuse.
• Circuitry open/shorted.
• Damaged multi-function switch.

• GO to Pinpoint Test E .

do your flash to pass lamps light when you pull the stalk towards you? If yes, the bulbs are ok.
Do the hig beams work?
Your headlamps have sepaerate fuses for each headlamp and you have a low beam relay and a high beam relay under the hood in the black box.
If everything is out, I suspect a bad headlamp switch.
Check car-part.com and look on page with * for cheapest price.

Your owner manual will identify fuses & relays.

PS, You did not recently instal high current bulbs did you? If yes, put originals back in.

HEADLAMPS

The voltage is supplied to the lamp switch through a fuse. This fuse is located in the central junction box in the left-hand footwell.
When the headlamps are switched on, a voltage is supplied to the high beam/low beam switch and to the low beam relay. The relay for the low beam is located in the battery junction box (BJB) in the engine compartment.
If the high beam/low beam switch is set to "low beam", then a voltage is supplied through the low beam relay to the low beam part of the headlamp assembly. The left and right-hand low beams are fused separately. The fuses are located in the battery junction box (BJB) in the engine compartment.
If the high beam/low beam switch is set to "high beam", then a voltage is supplied through the high beam relay to the high beam part of the headlamp assembly. The left and right-hand high beams are fused separately. The fuses are located in the battery junction box (BJB) in the engine compartment.

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Lamp Switch
Removal

1. CAUTION: Disconnect the battery ground cable. For additional information, refer to Section 414-01 .
   Remove the lower driver's side footwell trim.

1. Detach the lamp switch bezel.
   • Remove two screws.

1. Remove the light switch.
   • Remove three screws.
• Disconnect the electrical connector