The interior lighting system consists of two subsystems: The interior lamps and the demand lamps.
The interior lamps are controlled by the front electronics module (FEM). The interior lamp subsystem consists of the left and right puddle lamps, footwell lamps, map lamps and the grab handle lamps. The FEM controls the interior lamps by providing the ground circuit when a door ajar is detected.
The demand lamps subsystem consists of the glove compartment lamp, luggage compartment lamp, front map lamps, left and right vanity mirror lamps and the rear grab handle reading lamps. Each of these lamps are switched individually and share a common ground circuit.
Both subsystems use the same power supply circuit through switched system power (SSP) relay 3, with the exception of the luggage compartment lamp which is powered through SSP relay 4.
Principles of Operation
Note. A new front electronic module (FEM) or rear electronic module (REM) must be reconfigured before installing. REFER to MODULE COMMUNICATIONS NETWORK .
The electronic functions are divided into zones. The FEM controls the front portion of the vehicle and the REM controls the rear portion of the vehicle. These systems rely on the standard corporate protocol (SCP) communication network in order to transmit and receive signals. As a technician, it is very important to understand
- where the input (command) originates from.
- all information (messages) necessary in order for a feature to operate.
- which module(s) receive(s) the input or command message.
- whether the module which received the input (message) controls the output of the feature, or whether it outputs a message over the SCP communication network to another module.
- which module controls the output of the feature.
FEM Operation
This system is unique in that many of the inputs the FEM receives are delivered via the SCP communication network. These input messages come from other modules connected to the network, such as the rear electronics module (REM), driver door module (DDM), and instrument cluster. The FEM interprets the inputs and, in turn, commands the correct output. The FEM also receives inputs which come directly from components hardwired to the module, such as the front door ajar switches.
The FEM controls the outputs to all interior lighting. The lamps are illuminated if any door is ajar. The front door switches are hardwired to the FEM. When either of the two doors is opened, the FEM commands the interior lamps on by supplying the ground circuit. The rear door ajar switches are hardwired to the REM. When any of these doors are ajar, the REM sends a command through the SCP network to the FEM. The FEM then commands the appropriate interior lamps on.
Fault management of the interior lamps provides limited functionality in the event of certain dome or lighting mode inputs, vehicle speed or ignition switch failures. All interior lighting is powered by the switched system power (SSP) feature (see below). A failure of any or all of the SSP feature(s) could cause inoperative interior lighting. When diagnosing the interior lighting, it is essential to determine if all relative symptoms and DTCs are controlled by the SSP feature.
Normal Operation
The interior lighting feature provides interior lighting whenever a door is ajar. The interior lamps are controlled through the FEM. The FEM provides the ground circuit for the front dome/map lamps, rear grab handle lamps, RH and LH footwell lamps and the RH and LH puddle lamps through common circuit 31S-LC3 (BK/BU). Power for the interior lamps is supplied through common circuit 29S-LB2 (OG/BU) from switched system power (SSP) relay 3.
The interior lighting feature provides interior lighting whenever a door is ajar. The interior lamps are controlled through the FEM. The FEM provides the ground circuit for the front dome/map lamps, rear grab handle lamps, RH and LH footwell lamps and the RH and LH puddle lamps through common circuit 31S-LC3 (BK/BU). Power for the interior lamps is supplied through common circuit 29S-LB2 (OG/BU) from switched system power (SSP) relay 3. The LH and RH dome/map lamps and LH and RH grab handle lamps share a common power supply splice from circuit 29S-LB2 (OG/BU) and a common ground circuit splice to circuit 9-LB1 (BN/RD). The LH and RH puddle lamps and LH and RH footwell lamps are supplied power from circuit 29S-LB2 (OG/BU) through the central junction box (CJB). All interior lamp ground circuits connect at the auxiliary junction box and combine into one common ground circuit 29S-LC3 (BK/OG).
The interior lighting feature provides interior lighting whenever a door is ajar. The interior lamps are controlled through the FEM. The FEM provides the ground circuit for the front dome/map lamps, rear grab handle lamps, RH and LH footwell lamps and the RH and LH puddle lamps through common circuit 31S-LC3 (BK/BU). Power for the interior lamps is supplied through common circuit 29S-LB2 (OG/BU) from switched system power (SSP) relay 3. The LH and RH dome/map lamps and LH and RH grab handle lamps share a common power supply splice from circuit 29S-LB2 (OG/BU) and a common ground circuit splice to circuit 9-LB1 (BN). The LH and RH puddle lamps and LH and RH footwell lamps are supplied power from circuit 29S-LB2 (OG/BU) through the central junction box (CJB). All interior lamp ground circuits connect at the auxiliary junction box and combine into one common ground circuit 29S-LC3 (OG).
The demand lamps consist of the glove compartment lamp, LH and RH map lamps, LH and RH vanity mirror lamps and the LH and RH grab handle lamps. Switched system power is supplied to these lamps through SSP relay 3, and circuit 29S-LB2 (OG/BU). The glove compartment lamp uses ground circuit 31-LB8 (BK/OG). All other demand lamps are spliced into a common ground circuit 31-LB3 (BK/OG).
The luggage compartment lamp is controlled through the REM. SSP relay 4 supplies power to the lamp through circuit 29S-LB4 (OG/BK). The luggage compartment lid ajar switch provides a ground signal to the REM through circuit 8-GL20 (WH/BK) which, in turn, provides a ground signal to the luggage compartment lamp through circuit 31S-LB25 (BK/BU).
The luggage compartment lamp is controlled through the REM. SSP relay 4 supplies power to the lamp through circuit 29S-LB4 (OG/BK). The luggage compartment lid ajar switch provides a ground signal to the REM through circuit 8-GL20 (WH/BK) which, in turn, provides a ground signal to the luggage compartment lamp through circuit 31S-LB25 (BK/BU).