Question about 2003 Mercury Grand Marquis

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Can I bypass the LCM to install a headlamp switch?

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  • yadayada
    yadayada Nov 14, 2010

    The LCM controls more than just the headlights, so the answer is no

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  • Mercury Master
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No LCM runs lots of stuff. Guy oin ebay fixes them for about $100 all the time. Type LCM repair.

Posted on Dec 03, 2010

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Posted on Jan 02, 2017

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SOURCE: 1999 olds aurora,headlamps wont turn off,sometimes will blink.

those are problems with the olds light switches, same switch used on other gm vehicles. replace it , new or salvage yard

Posted on Sep 18, 2009

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2005 merc grand marquis Headlights keep blowing a fuse


Does your Grand Marquis have head lamps with auto lamps ? Which fuse keeps blowing ? Could be a shorted LCM - lighting control module ?

Lighting Control Module (LCM)
The LCM eliminates the electronic interference and heat associated with the thermoelectric devices used previously. The LCM is a microprocessor-based module that controls several vehicle subsystems. It responds to electrical input signals from various switches, sensors, and external modules..

Visual Inspection Chart Mechanical Electrical
  • Headlamp switch
  • Central junction box (CJB) fuse(s).
    • 1 (15A)
    • 9 (20A)
    • 26 (10A)
    • 15 (7.5A)
    • 7 (10A)
  • Headlamp bulb
  • Circuitry
  • Headlamp switch
  • Lighting control module (LCM)
  • Underhood power distribution box (PDB)
    • F104 (40A)
    • F01 (20A)
    • F02 (25A)

Feb 12, 2017 | Cars & Trucks

1 Answer

Right low beam headlight does not come on but my right turn signal will stay even tho i diddnt turn it on. If I cut on my high beams the rurn signal cuts off. Whats wrong? Helo


It could be the lamp control module !
Headlamps
Battery positive voltage (B+) is applied at all times to the lamp control module (LCM) through the underhood fuse block HDLP fuse.
When you place the headlamp switch in the HEAD position, the headlamps input to the LCM is grounded. The LCM then applies battery positive voltage (B+) through the underhood fuse block HDLOBML fuse and HDLOBMR fuse, which feed the left low beam headlamp and the right low beam headlamp respectively. When you activate the headlamp dimmer switch by pulling on the multifunction lever until the switch clicks, the high beam input circuit to the LCM in grounded . The LCM then removes battery positive voltage (B+) from the low beam headlamps and supplies battery positive voltage (B+) through the underhood fuse block HDHIBML fuse and HDHIBMR fuse, which feed the left high beam headlamp and the right high beam headlamp respectively.
Check this fuse in the left under hood fuse box first. HDLOBMR Fuse 18 10 Amp. RH Low Beam Headlamp . If the fuse is good check for B+ voltage with the low beams on . Use a test light or volt meter . If you look on top of fuse there are two metal tabs ,check there for B+ voltage , If no B+ voltage the LCM - lamp control module isn't supplying any .
Lamp Control Module (LCM)
Under the left side of the IP, to the right of the steering column
Turn Signal Flasher
Under the left side of the IP, to the right of the steering column
Lighting Systems Component Views in Lighting Systems
Lighting Systems Connector End Views in Lighting Systems
Turn Signal/Hazard Switch
In the left front of the passenger compartment, in the steering column

Apr 28, 2016 | 2000 Buick Park Avenue

1 Answer

Why doesn't my speedometer/odometer, horn and headlights work?


Which insturment cluster does your's have ? electronic instrument cluster or standard instrument cluster !

Standard insturment cluster - speedo / odometer
Speedometer/Odometer
The speedometer and odometer provides speed information based on a speed/distance pulse signal from the vehicle speed sensor (VSS). The VSS is mounted on the speedometer driven gear in the transmission.
Could be the VSS is bad .
Horn The horn system includes the following:
  • horn relay
  • horn
  • clock spring
  • steering wheel control switch harness
  • steering wheel pad horn switch, which is part of the driver side air bag module. For additional information, refer to Section 501-20B .
The horn is located behind the front bumper mounted to the radiator support.

Is the air bag light lit on the insturment cluster ? If it is the clock spring could be the problem . If not lit check the circuits from the horn relay .

VEHICLE RELAYS Operation Diagnosis .

Which headlamps don't work ? Low beams , high beams , both ?
  • The high beams are inoperative
  • Bulbs.
  • Circuitry.
  • Multifunction switch.
  • GO to Pinpoint Test C .
  • The low beams are inoperative
  • Bulbs.
  • Circuitry.
  • Headlamp switch.
  • Multifunction switch.
  • LCM.
  • GO to Pinpoint Test D .
Principles of Operation
NOTE: Due to varying wattage ratings and resulting current draw, certain aftermarket headlamp bulbs may cause the lighting control module (LCM) to shut down the short circuit protection, resulting in the low beams becoming inoperative. Verify that the headlamp bulbs meet Ford specifications.
Headlamp System The headlamp system consists of:
  • two aerodynamic halogen headlamp bulbs and retainers
  • headlamp switch
  • multifunction switch
  • lighting control module (LCM)
  • circuit wiring and circuit protection
In normal operation:
  • With the multifunction switch in the low beam position, power is supplied by the LCM to the low beam elements through the multifunction switch.
  • With the multifunction switch in the high beam position (forward detent), power is supplied to the high beam elements and to the high beam indicator in the instrument cluster.
  • When the multifunction switch is pulled toward the steering wheel, the flash-to-pass switch (part of the multifunction switch) is closed and power is supplied to the high beam elements. When the switch is released, they return to low beam operation.
  • The battery saver feature of the LCM will automatically turn off the courtesy lamps, demand lamps, headlamps, or parking lamps under the following conditions:
    • The ignition switch is in the OFF position.
    • The headlamp switch is in parking lamps ON or headlamps ON positions.
    • After 10 minutes.
Headlamp Switch The headlamp switch is a multi-position switch.
  • The positions include OFF, PARK, and HEAD.
  • With the headlamp switch in the PARK position (first detent), a signal is supplied to the LCM which powers the front parking lamps, the tail lamps, the side marker lamps, and the license lamp.
  • With the headlamp switch in the HEAD position, power is supplied to the headlamps through the LCM and the multifunction switch.
  • The panel dim switch (part of the headlamp switch) is located above the headlamp switch. The panel dim switch operates only with the parking lamps or headlamps on.
  • When the panel dim switch is held in the up position, the instrument panel lighting will progressively brighten.
  • When the panel dim switch is held in the down position, the instrument panel lighting will progressively dim.
For additional information, refer to Section 413-00 .
Headlamps On Warning Chime If the headlamp switch is left in either the PARK or HEAD position and the driver door is opened, the LCM will sound a headlamps on reminder chime when the following conditions occur:
  • The ignition switch is OFF with the ignition key out.
  • The driver door is ajar.
For additional information, refer to Section 413-09 .

Inspection and Verification
  1. Verify the customer concern by operating the system.
  1. Visually inspect for obvious signs of mechanical and electrical damage.


Visual Inspection Chart Mechanical Electrical
  • Headlamp switch
  • Central junction box (CJB) fuse(s):
    • 6 (15A)
    • 15 (15A)
    • 21 (15A)
    • 23 (15A)
    • 27 (20A)
  • Battery junction box (BJB) HI-BEAM HEADLIGHTS (20A) fuse
  • Circuitry
  • Headlamp bulb
  • Lighting control module (LCM)
  • Loose or corroded connections

Jul 10, 2017 | 2003 Ford Crown Victoria

1 Answer

Replace dimmer switch


The headlamps ( high an low ) are controlled by the LCM lamp control module .
Headlamp Dimmer Switch
Under the left side of the IP, on the base of the steering column

Headlights Circuit Description (Buick)
Battery positive voltage (B+) is supplied at all times to the lamp control module (LCM) through the LH underhood fuse block LCM/HDLP circuit breaker via CKT 242 (RED). When the headlamp switch is placed in the ON position, the headlamp switch input to the LCM is grounded via CKT 103 (WHT). The LCM then supplies battery positive voltage (B+) via CKT 12 (TAN) to the following components:
• Left low beam headlamp
• Right low beam headlamp
When the headlamp dimmer switch is placed in the HIGH position, the LCM removes battery positive voltage (B+) from the low beam headlamps. The LCM supplies battery positive voltage (B+) via CKT 11 (LT GRN) to the following components:
• Left high beam headlamp
• Right high beam headlamp
The LCM provides battery positive voltage (B+) to the appropriate headlamps under the following conditions:
• The ignition switch is in the RUN position.
• The ambient light sensor indicates darkness.
The lamp control module (LCM) monitors the ambient light conditions through the ambient light sensor. The ambient light sensor is a variable resistor whose resistance changes as the surrounding ambient light level changes. As the ambient light decreases, the resistance of the ambient light sensor increases. The LCM measures the resistance across the ambient light sensor and determines whether it is day or night.

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Do you know how to test automotive electrical circuits ? Check power in an power out . Videos on youtube on basic automotive electrical testing .

Mar 08, 2017 | Buick LeSabre Cars & Trucks

1 Answer

Twilight sentinel will not work; now headlight and tail lights won't come on; interior lights still work with knob. Do you think it is the F-switch? Also, where can I get a schematic of how to ins


It's probably the lighting control module , but without doing some electrical testing that is just a guess !
Battery positive voltage (B+) is applied at all times to the lamp control module (LCM) through the underhood junction block HDLP MaxiFuse® and CKT 1242 (RED).
When you place the headlamp switch in the HEAD position, the headlamps input to the LCM is grounded. The LCM then applies battery positive voltage (B+) through the underhood junction block HDLOBML fuse and HDLOBMR fuse, which feed the left low beam headlamp and the right low beam headlamp respectively. When you activate the headlamp dimmer switch by pulling on the multifunction lever until the switch clicks, CKT 524 (PPL) is grounded to the LCM. The LCM then removes battery positive voltage (B+) from the low beam headlamps and supplies battery positive voltage (B+) through the underhood junction block HDHIBML fuse and HDHIBMR fuse, which feed the left high beam headlamp and the right high beam headlamp respectively.

Twilight Sentinel Circuit Description
Twilight sentinel determines whether the daytime running lamps (DRL), or the exterior lamps and the low beam headlamps at full intensity should be on based upon the signal of the ambient light sensor. When the ambient light sensor detects daytime, the twilight sentinel turns on the DRL. When the ambient light sensor detects darkness, the twilight sentinel turns on the exterior lamps and the low beam headlamps at full intensity. The twilight sentinel also keeps the lamps on for a delay period of 3 to 180 seconds under the following conditions:
• The vehicle is in PARK.
• The ambient light sensor detects darkness.
• The ignition switch is turned to the OFF position.
You may turn off the twilight sentinel manually. When it is dark and the gear selector is in PARK, pushing the twilight sentinel switch to OFF will turn off the headlamps and exterior lamps. Pushing the twilight sentinel switch to OFF again will turn on the headlamps and the exterior lamps. If the gear selector is not in PARK, pushing the twilight sentinel switch will have no effect.
The F- switch is just an input from the LCM - lamp control module .
Do you know how to test control module inputs an outputs ? Very easy to fry a module if you don't know how to do it .
Also have a full scan of all modules on the vehicle , could have DTC'S - diagnostic trouble codes stored . Not for the OBD 2 engine computer . The instrument cluster , BCM , LCM can all set codes too, related to lighting an someother thing's .
ECM Inputs and Outputs Diagnosis

Electric Testing Techniques You Need to Know

You can find free wiring diagrams here http://www.bbbind.com/free_tsb.html Enter vehicle info. year , make , model and engine ! Under system click on lighting ,then under subsystem click headlamps . Click the search button then the blue link . The first diagram you will see at the top the power supply to the LCM , down a little you will see the headlamp switch , ambient light sensor . Now if you want to start replacing thing's without testing good luck !

Jun 02, 2017 | 1997 Buick Park Avenue

1 Answer

Can't turn off headlights on 2001 crwn victoria polce intercepter


I hate to say this but it sounds like the dreaded expensive LCM, Lighting Control Module. It is the common cause. New is $550. It is above the brake pedal and steering coumn under the dash.

There is a guy on ebay who fixes them and sells you the last one he fixed. Then you send yours back for a core charge refund. He is in California.

Here is what it controls. DO you have auto lamps? Also, pleae rate this help, thx

Lighting Control Module (LCM)
The LCM eliminates the electronic interference and heat associated with the thermoelectric devices used previously. The LCM is a microprocessor- based module that controls several vehicle subsystems. It responds to electrical input signals from various switches, sensors, and external modules.
LCM subsystem functions include:
  • headlamps with autolamps
  • turn signal lamps/hazard flasher lamps
  • cornering lamps
  • parking lamps
  • courtesy lamps
  • demand lamps
  • battery saver
  • backlighting
------------------------------------------------------------
The system consists of:
  • a light-sensitive light sensor amplifier
  • a lighting control module (LCM)
  • an autolamp time delay control (part of the headlamp switch and includes an OFF position)
------------------------------------------------------------------------------------------------------------------
see owner manual for fuse box location
  • The autolamps are inoperative - the autolamps are always on
  • CJB fuse 21 (15A).
  • Circuitry.
  • Autolamp switch (part of the headlamp switch).
  • Light sensor amplifier.
  • LCM.

---------------------------------------------------------------------------------------------------------
dealer has scan tool to do this test. About 1/2 hour labor charge.
  1. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.
  1. If the concern remains after the inspection, connect the diagnostic tool to the data link connector (DLC) located beneath the instrument panel and select the vehicle to be tested from the diagnostic tool menu. If the diagnostic tool does not communicate with the vehicle:
    • check that the program card is correctly installed.
    • check the connections to the vehicle.
    • check the ignition switch position.
  1. If the diagnostic tool still does not communicate with the vehicle, refer to the diagnostic tool manual.
  1. Carry out the DATA LINK DIAGNOSTIC TEST. If the diagnostic tool responds with:
    • CKT914, CKT915 or CKT70 = ALL ECUS NO RESP/NOT EQUIP, refer to Section 418-00 .
    • NO RESP/NOT EQUIP for LCM, refer to Section 419-10 .
    • SYSTEM PASSED, retrieve and record the continuous diagnostic trouble codes (DTCs), erase the continuous DTCs and carry out the self-test diagnostics for the LCM.
  1. If the DTCs retrieved are related to the concern, go to the LCM Diagnostic Trouble Code (DTC) Index.
-------------------------------------------------------------------------
Module -Lighting Control (LCM) Removal and Installation
  1. s1a~us~en~file=ani_caut.gif~gen~ref.gif CAUTION: Prior to removal of the lighting control module (LCM), it is necessary to upload module configuration information to a diagnostic tool. This information needs to be downloaded into the new module once installed. For additional information, refer to Section 418-01 .
    Disconnect the battery ground cable. For additional information, refer to Section 414-01 .
  1. Remove the LH instrument panel lower insulator.
    1. Remove the pin-type retainers.
    1. Disconnect the courtesy lamp.
  1. If equipped with adjustable pedals, remove the accelerator pedals, and shaft. For additional information, refer to Section 310-02 .
  1. Position the LCM aside.
    1. Remove the screws.
    1. Release the locking tab.
  1. Disconnect the electrical connectors and remove the LCM.

snorkelbobby_69.gif

Jun 23, 2011 | Ford Crown Victoria Cars & Trucks

1 Answer

1999 olds aurora,headlamps wont turn off,sometimes will blink.


those are problems with the olds light switches, same switch used on other gm vehicles. replace it , new or salvage yard

Sep 18, 2009 | 1999 Oldsmobile Aurora

1 Answer

2004 crown vic interior lights stay on


Don't think you have a door ajar switch problem , more then like the lighting control module is the culprit . Does the door ajar light on the instrument cluster stay lit ?
The interior lighting can be separated into two distinct modes of operation: the courtesy lighting and the demand lighting. The lighting control module (LCM) controls all of the interior lighting in the vehicle, as described in the following text.
The front dome lamps, rear reading lamps, and instrument panel courtesy lamps, can be illuminated either by opening any of the vehicle doors (courtesy lamp function) or by depressing the headlamp switch (demand lamp function).
When any door is open, the door ajar switch grounds an input to the LCM which then sends power to the courtesy lamps. The voltage sent to the courtesy lamps gradually increases from 0 volts to 12 volts within 500 ms (± 50 ms), to achieve the theater lighting effect. When the door(s) are closed the door ajar switch(es) break(s) the ground to the LCM input which then gradually reduces the power from 12 volts to 0 volts within 5 seconds. (± .5 second).
When the headlamp switch is depressed it grounds an input to the LCM which in turn sends 12 volts to the front dome lamps, rear reading lamps, and instrument panel courtesy lamps. When the headlamp switch is depressed a second time, it breaks the ground to the LCM input which then ceases to send power to the front dome lamps, rear reading lamps, and instrument panel courtesy lamps.

The battery saver will disrupt power to the courtesy lamps after 10 minutes, the demand lamps after 30 minutes, and the headlamps after 10 minutes. Turning the ignition switch to the RUN or ACC position will terminate the battery saver feature by disabling the interrupt timers and reinstate power to the lamps.
Do you know what DTC'S are ? diagnostic trouble codes !
LCM Diagnostic Trouble Code (DTC) Index DTC Description Source Action B1322 Driver Door Ajar Circuit Short to Ground LCM Go To Pinpoint Test F . B1442 Door Handle Switch Circuit Failure LCM Go To Pinpoint Test G . B1445 Door Handle Switch Circuit Short to Ground LCM Go To Pinpoint Test G . B1563 Door Ajar Circuit Failure LCM Go To Pinpoint Test C . B1566 Door Ajar Circuit Short to Ground LCM Go To Pinpoint Test H . B1685 Lamp Dome Input Circuit Failure LCM Go To Pinpoint Test I . B1687 Lamp Dome Input Circuit Short to Battery LCM Go To Pinpoint Test I . - All Other DTCs LCM REFER to Section 419-10 .

PINPOINT TEST C: THE COURTESY LAMPS STAY ON CONTINUOUSLY CONDITIONS DETAILS/RESULTS/ACTIONS C1 CHECK THE SYSTEM OPERATION Open and close each door, making sure that each door is completely closed.
  • Are the courtesy lamps still illuminated after the 25 second time-out period?
Yes GO to C2 .

No The system is operating correctly. C2 TEST DOME LAMP SWITCH Depress the dome lamp switch.
  • Are the courtesy lamps still illuminated?
Yes DEPRESS the dome lamp switch a second time. GO to C3 .

No The system is operating correctly. C3 CHECK THE LIGHTING CONTROL MODULE
LCM C2145a

  • Are the courtesy lamps still illuminated?
Yes REPAIR circuit 53 (BK/LB). REPEAT the self-test. CLEAR the DTCs.

No INSTALL a new LCM. REFER to Section 419-10 . REPEAT the self-test. CLEAR the DTCs.

Apr 16, 2017 | 2004 Ford Crown Victoria

1 Answer

Headlights won't come on, now car won't start.


It is definitely the Lighting Control Module. Just fixed one for a friend. It has internal printed circuit board failure.
It is easy repair but it is expensive. New are 500. Controls much more than lights. Alarm, air bag, door key pad, etc.

You need to have correct part for 2003. tascafordparts,com has the for about $250.

It's just above brake pedal. remove the sond panel. The module will come out without removing other components.

Lighting Control Module (LCM)
The LCM eliminates the electronic interference and heat associated with the thermoelectric devices used previously. The LCM is a microprocessor- based module that controls several vehicle subsystems. It responds to electrical input signals from various switches, sensors, and external modules.
LCM exterior lighting subsystem functions include:
  • headlamps with autolamps (if equipped)
  • turn signal lamps/hazard flasher lamps
  • cornering lamps
  • parking lamps
  • battery saver
Principles of Operation
The lighting control module (LCM) is a microprocessor-based module that controls several vehicle subsystems. The LCM responds to electrical input signals from various switches, sensors, and external modules. The LCM is located under the LH side of the instrument panel. Subsystem functions of the LCM include headlamps with autolamps, turn signal lamps/hazard flasher lamps, cornering lamps, parking lamps, courtesy lamps, demand lamps, battery saver and control backlighting.
Module —Lighting Control (LCM) Removal and Installation

  1. Remove the LH instrument panel lower insulator.
    1. Remove the pin-type retainers.
    1. Disconnect the courtesy lamp.
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  1. Position the LCM aside.
    1. Remove the screws.
    1. Release the locking tab.
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  1. Disconnect the electrical connectors and remove the LCM.
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Apr 20, 2009 | 2003 Mercury Grand Marquis

1 Answer

No high beam headlights 1996 crown victoria


does the flash to pass function work? That uses high beam bulbs.

If yes, I would bet $100 it's the lighting control module. Very expensive. @ $500. Can buy for $250 @ tascafordparts.com.

Sometimes on Ebay for cheap price.

--------------------------------
Lighting Control Module Principles of Operation
NOTE: Due to varying wattage ratings and resulting current draw, certain aftermarket headlamp bulbs may cause the lighting control module (LCM) to shut down the short circuit protection, resulting in the low beams becoming inoperative. Verify that the headlamp bulbs meet Ford specifications.
The lighting control module (LCM) receives inputs from the following:
  • headlamp switch
  • multifunction switch
  • photocell and amplifier
Depending on the inputs received, the LCM will command the headlamps on or off.

Power is supplied to the headlamps through lighting control module Circuit 502 (GY) and circuit protection C in the fuse junction panel. Ground is provided to the headlamp bulb and retainer (13N021) through Circuit 57 (BK).

The lighting control module is located under the instrument panel, to the right of the steering column, under the lower steering column cover.

Removal and Installation
  1. Open hood. Disconnect battery ground cable (14301).
  1. Disengage three pushpins and remove lower driver side intrument panel (04320) finish panel.
  1. Locate lighting control module above accelerator pedal.
  1. Disconnect bottom two eletrical connectors from lighting control module.
  1. Remove two screws retaining LCM to bracket and unclip from bracket.
  1. Remove lighting control module from bracket and disconnect two remaining electrical connectors.
  1. To install, reverse Removal procedure. Check lighting control module for proper operation.
---------------------------------

the module is about 6 inches lng and 4 inches wide and has 3 wire connectors.

Jul 30, 2008 | 1996 Ford Crown Victoria

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