The interior lighting system consists of the following components
- Smart junction box (SJB)
- Dimmer control switch
- Interior/map lamps
- Luggage compartment lamp
- Vanity mirror lamps
- Door ajar switches
The interior lighting system consists of 2 subsystems
- Courtesy lamps
- Demand lamps
The courtesy lamps are controlled by the SJB. The SJB supplies voltage to the courtesy lamps. The courtesy lamp subsystem consists of the interior dome lamps, the overhead console lamps (if equipped), and the puddle lamps (if equipped).
The demand lamps are controlled by the SJB. The SJB supplies voltage to the demand lamps. The demand lamps subsystem consists of the luggage compartment lamp, front map lamps, and the left and right vanity mirror lamps.
The SJB supplies power to the interior lighting system. The SJB will set DTCs if certain circuit failures exist with the interior lighting system.
Special Tools Illustration Tool Name Tool Number 73III Automotive Meter 105-R0057 or equivalent Vehicle Communications Module (VCM) and Integrated Diagnostic System (IDS) software with appropriate hardware, or equivalent scan tool Flex Probe Kit 105-R025C or equivalent
Scheme 1
Scheme 2
Principles of Operation
The smart junction box (SJB) supplies voltage to the interior lighting system. The interior lighting system illuminates the courtesy lamps to enhance visibility of the interior while a vehicle door is open or ajar, and the vehicle speed is less than 15 km/h (9 mph). The SJB controls all interior lighting functions and timing by monitoring inputs from the door ajar switches and vehicle speed.
The interior lighting delay feature provides temporary illumination of the courtesy lamps after the doors are opened and then closed. The interior lighting delay feature will keep the courtesy lamps on for a period of 25 seconds. If during the 25 second delay time the SJB detects that the ignition has been turned ON, or if the vehicle is locked using the remote keyless entry (RKE) transmitter or the keypad, the courtesy lamp illumination will be discontinued.
Normal Operation
Power is supplied to the courtesy lamps through the smart junction box (SJB) fuse 3 (15A), which supplies voltage to the courtesy lamps/demand lamps. When any door is opened, the ajar switch opens, signaling the SJB. The SJB monitors the ajar circuits, and based on the ajar status, the SJB will supply voltage to the courtesy lamps on circuit CLN26 (BU). Ground for the courtesy lamps is supplied through circuit GD139 (BK/YE).
Possible Causes
- Fuse
- Circuit CLN09 (YE/GN) short to ground
- Circuit CLN26 (BU) open or short to ground
- Circuit GD139 (BK/YE) open
- SJB
The smart junction box (SJB) provides voltage to the courtesy lamps on circuit CLN26 (BU). The courtesy lamps are grounded through circuit GD139 (BK/YE). The luggage compartment lamp is also on the courtesy lamp circuit. Circuit CLN26 (BU) provides voltage to the luggage compartment lamp, and the lamp is grounded through circuit GD139 (BK/YE).
Possible Causes
- Circuit CLN26 (BU) open
- Circuit GD139 (BK/YE) open
- Interior lamp
When any door is open, including the luggage compartment lid, the ajar switch opens the circuit to the smart junction box (SJB). The SJB monitors the ajar circuits and the dimmer switch, and based on the input, the SJB will supply voltage to the courtesy lamps on circuit CLN26 (BU).
Possible Causes
- Circuit CLN26 (BU) short to voltage
- Circuit CLN28 (GN/BU) short to ground
- Circuit CPL26 (GN/VT) open
- Circuit CPL31 (WH) open
- Circuit CPL36 (GN) open
- Circuit CPL39 (YE) open
- Circuit CPL44 (YE/OG) open
- Dimmer switch
- Door ajar switch
- Luggage compartment lid ajar switch
- SJB
When any door is open, including the luggage compartment lid, the ajar switch opens the circuit to the smart junction box (SJB). The SJB monitors the ajar circuits, and based on the ajar status, the SJB will supply voltage to the courtesy lamps on circuit CLN26 (BU).
Possible Causes
- Circuit CPL26 (GN/VT) short to ground
- Circuit CPL31 (WH) short to ground
- Circuit CPL36 (GN) short to ground
- Circuit CPL39 (YE) short to ground
- Circuit CPL44 (YE/OG) short to ground
- Circuit GD171 (BK/GY) open
- Door ajar switch
- Luggage compartment lid ajar switch
- SJB
The smart junction box (SJB) supplies voltage to the demand lamps on circuit CLN09 (YE/GN). The demand lamps are grounded through circuit GD139 (BK/YE). The glove compartment lamp (MKZ only) is case grounded.
Possible Causes
- Circuit CLN09 (YE/GN) open
- SJB
The smart junction box (SJB) supplies voltage to the demand lamps on circuit CLN09 (YE/GN). The demand lamps are grounded through circuit GD139 (BK/YE). The glove compartment lamp (MKZ only) is case grounded.
Possible Causes
- Circuit CLN09 (YE/GN) open
- Circuit GD139 (BK/YE) open
- Interior lamp
The illuminated entry provides interior lighting whenever the smart junction box (SJB) receives a doors unlock request from the RKE transmitter. The SJB provides voltage on circuit CLN26 (BU) for the courtesy lamps.
Possible Causes
- RKE system
- SJB
The smart junction box (SJB) provides a battery saver function. The battery saver function provides automatic shutoff of the interior lamps (courtesy lamps and demand lamps) after a predetermined time has elapsed in order to save battery power.
Possible Causes
- Circuit CLN09 (YE/GN) short to voltage
- SJB
The smart junction box (SJB) provides voltage to the puddle lamps through circuit CLN26 (BU). The puddle lamps have separate ground circuits. The LH exterior mirror is grounded through circuit GD126 (BK/WH), and the RH exterior mirror is grounded through circuit GD139 (BK/YE).
Possible Causes
- Circuit CLN26 (BU) open
- Circuit GD126 (BK/WH) open
- Circuit GD139 (BK/YE) open
- Exterior mirror
The smart junction box (SJB) monitors the dimmer switch status on circuit CLN28 (GN/BU) to determine if the courtesy lamps are requested. Based on the dimmer switch status, the SJB supplies voltage to the courtesy lamps through circuit CLN26 (BU).
Possible Causes
- Circuit CLN28 (GN/BU) open or short to ground
- Dimmer switch
- SJB