Lighting - Headlamps Stay ON With Switch Turned OFF
TSB 06-19-1110/02/06
DTC B2498 - HEADLAMP FUNCTIONALITY (FAULT
DETECTION) - HEADLAMPS STAY ON AFTER
SWITCH IS OFF
FORD:
2006 Fusion
LINCOLN:
2006 Zephyr
MERCURY:
2006 Milan
ISSUE
Some 2006 Fusion, Milan, and Zephyr vehicles may experience headlamps remaining illuminated when the vehicle is not running and headlamp switch is in the off position with diagnostic trouble code (DTC) B2498 stored in memory.
ACTION
Follow the Service Procedure steps to correct the condition.
SERVICE PROCEDURE
The smart junction box (SJB) / generic electronic module (GEM) controls the exterior lighting functionality and has fault detection / mitigation strategies designed to induce as little impact to the end customer as possible.
The SJB / GEM receives command signals directly from the headlamp switch. The positions of the headlamp switch that drive input signals to the SJB / GEM, are Off, Park Lamps, and Headlamps (and Auto Lamps, as an option).
At any given time, exactly one of these signals should be active: Off or Park Lamps or Headlamps (or Auto Lamps, if equipped). If two (2) or more of these signals are active at the same time and remain active for at least 5 seconds, or if NONE of the signals are active for at least 5 seconds, then the SJB I GEM considers the input side of the exterior lighting subsystem to have a fault and will set DTC B2498 (Headlamp Switch Multiple Signals Input Active) and implement a planned subsystem fault strategy based on the specific fault.
In many cases, this will be transparent to the customer. Although depending on the specific fault, the SJB's / GEM's functional reaction may not necessarily be transparent to the customer.
For Example:
If the subsystem fault conditions are correct, the SJB might turn the headlamps on after a 5 second delay, and keep the headlamps on for 10 minutes (until the Battery Saver feature kicks in).
NOTE
THIS BEHAVIOR IS PART OF THE SJB / GEM DESIGN. IT DOES NOT MEAN THAT THERE IS A FAULT WITHIN THE SJB.
NOTE
THE FUSION, MILAN, AND ZEPHYR HEADLAMP SWITCH DESIGN IS SUCH THAT IT IS VERY EASY TO PUT THE HEADLAMP SWITCH IN BETWEEN "FIRM" VALID POSITIONS. IN BETWEEN PROPER POSITIONS, THE SWITCH COULD MAKE BOTH OF THE RELEVANT SIGNALS ACTIVE, ON OR NOT ACTIVE, OFF (BEING BETWEEN OFF AND PARK LAMPS).
Neither part should be replaced unless a true fault in one part or the other has been identified.
If DTC B2498 is found in the SJB I GEM to identify the portion of the subsystem: the headlamp switch, the SJB I GEM , and/or the wiring in between as the root cause, check the PIDs shown. (Figure 1)
Inputs from the headlamp switch should appear on an IDS or PDS as shown in the table for each headlamp switch position if there is no fault. Clear the DTC code, verify the proper switch function and advise the customer that was a normal system alert when the headlamp switch was left between two positions (Off-Park Lamps or Park Lamps-Headlamps or if equipped Auto lamp-Off).
If, for any of the headlamp switch positions, something other than what is in the table is seen, then the discrepant circuit(s) need to be investigated to determine where the fault is, according to Workshop Manual (WSM), Section 417-01 exterior lighting diagnosis and testing.
WARRANTY STATUS: Information Only
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