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Home >> Lincoln >> 2018 >> MKZ Select, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1577 (Exterior Lighting (Except Electric)) >> Description And Operation >> Exterior Lighting - System Operation and Component Description >> Turn Signal and Hazard Lamps

Turn Signal and Hazard Lamps

WARNING: This page is about a different car, the 2018 Ford Focus. However, it is still accessible from the selected car via links, so may be relevant.

System Diagram 

GFD269760Courtesy of FORD MOTOR COMPANY
Item Description
1 MS-CAN
2 LIN
3 SASM
4 FCIM
5 LH front turn lamp
6 RH front turn lamp
7 LH rear turn lamp
8 RH rear turn lamp
9 Ignition switch
10 Start/Stop switch
11 (with Sony Sound)
12 (with base or premium audio)
13 Hazard flasher lamp switch
14 DDM
15 PDM
16 LH exterior mirror
17 RH exterior mirror
18 (vehicles with one-touch down driver window)
19 (vehicles with one-touch up and down front windows)
20 LH exterior mirror
21 RH exterior mirror
22 HCM
23 LH cornering lamp
24 RH cornering lamp
25 (with High Intensity Discharge (HID) headlamps)
26 (without push button start)
27 (with push button start)
28 LH steering column multifunction switch

Network Message Chart 

DDM and PDM Network Input Messages 

Broadcast Message Originating Module Message Purpose
Turn indicator command BCM A command to the DDM or PDM to activate/deactivate the exterior mirror turn indicator.

HCM Network Input Messages 

Broadcast Message Originating Module Message Purpose
Turn indicator command BCM A command to the HCM to activate/deactivate the cornering lamp.

Turn Signals 

The SASM monitors the multifunction switch position. When the multifunction switch is in the left or right turn position, the SASM sends a turn signal switch status message over the LIN circuit to the BCM indicating a request for the left or right turn signal.

When the BCM receives a request for a turn signal, the BCM supplies on/off voltage to the appropriate turn lamps. The BCM sends a turn indicator command message over the MS-CAN to the door models for the exterior mirror turn lamps (if equipped) and the HCM for the front cornering lamps (High Intensity Discharge (HID) headlamps).

The timed on/off cycle for turn lamps is determined by the BCM and is set to flash approximately 70 times per minute if both the front and rear turn signal lamps operate correctly. If a front or rear turn signal lamp is inoperative, the BCM fast flashes the remaining turn lamp(s) approximately 150 times per minute to indicate a bulb outage to the driver.

The multifunction switch is a momentary contact switch, with 2 detents for the left turn position and 2 detents for the right turn position. When placed in the first detent and released, the corresponding turn signals flash 3 times and turn off. When the multifunction switch is moved to the second detent, the turn signal flashes until the steering wheel is turned in the opposite direction to mechanically return the multifunction switch to the rest position.

The BCM also provides Field Effect Transistor (FET) protection of the turn lamp output circuits. When an excessive current draw is detected, the BCM disables the affected circuit driver.

Refer to: Module Controlled Functions - System Operation and Component Description .

Hazard Lamps 

The BCM sends a voltage signal to the hazard flasher lamp switch (on vehicles equipped with base or premium audio systems, this is integrated into the FCIM) to monitor for a hazard lamp function request. When the hazard flasher lamp switch is pressed, the voltage signal is routed to ground, indicating a request to activate or deactivate the hazard lamp function.

When the BCM receives a request for the hazard lamps, the BCM supplies on/off voltage to all the turn lamps.

The timed on/off cycle for the hazard lamps is approximately 70 times per minute, regardless of bulb outage.