Exterior Lamps - Operation

OPERATION

Following are paragraphs that briefly describe the operation of each of the major exterior lighting systems. The lamps and the hard wired circuits between components related to the exterior lighting system may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, details of wire harness routing and retention, connector pin-out information and location views for the various wire harness connectors, splices and grounds.

However, conventional diagnostic methods will not prove conclusive in the diagnosis of the exterior lighting system or the electronic controls or communication between modules and other devices that provide some features of the exterior lighting system. The most reliable, efficient and accurate means to diagnose the exterior lighting system or the electronic controls and communication related to exterior lighting system operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.

AUTOMATIC HEADLAMPS

The optional automatic headlamp system includes the left (lighting) multi-function switch, the Steering Control Module (SCM), the ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN), the Totally Integrated Power Module (TIPM), the heater and air conditioner control unit and the sun load sensor on the top of the instrument panel. The A (Automatic) position must be selected using the left multi-function switch.

The A (Automatic) position must be selected using the left multi-function switch. Once this prerequisite has been met, the SCM responds by sending the appropriate electronic lighting request messages to the EMIC over the Local Interface Network (LIN) data bus. The EMIC relays this message to the TIPM over the Controller Area Network (CAN) data bus. The TIPM then monitors an ambient light level input received over the CAN bus from the EMIC or the heater and air conditioner control. When the engine is running, the TIPM responds to these messages by automatically controlling outputs to the selected headlamp circuits to illuminate the headlamps. The TIPM also sends the appropriate electronic messages back to the EMIC to control the illumination of the high beam indicator.

BACKUP LAMPS

The backup (or reverse) lamps have a path to ground at all times through a takeout and eyelet terminal of the body wire harness that is secured to the body sheet metal within the passenger compartment. On vehicles with a manual transmission, the backup lamp switch provides a hard wired input to the to the TIPM through a backup lamp switch signal circuit, and the TIPM provides battery voltage to the backup lamps on the backup lamp feed circuit whenever the ignition switch is in the ON position and the REVERSE position is selected with the transmission shift linkage.

On vehicles with an automatic transmission, the Powertrain Control Module (PCM) continually monitors a hard wired multiplex input from the Transmission Range Sensor (TRS), then sends the appropriate electronic transmission gear selector status messages to the TIPM over the CAN data bus. Whenever the ignition switch is in the ON position and the TIPM receives an input indicating the status of the transmission gear selector is REVERSE, it provides a battery voltage output through a high side driver to the backup lamps on the backup lamp feed circuit.

BRAKE LAMPS

The brake (or stop) lamps and the Center High Mounted Stop Lamp (CHMSL) each have a path to ground at all times through a takeout and eyelet terminal of the body wire harness that is secured to the body sheet metal within the passenger compartment. The CHMSL receives battery voltage directly on the brake lamp switch output circuit when the brake lamp switch is closed by the brake pedal arm. The TIPM also receives battery voltage on the brake lamp switch output circuit, which it uses as a signal to energize the brake lamps. The TIPM provides battery voltage to the brake lamps through a high side driver on the tail/stop lamp rear feed circuit when it receives the proper input from the closed brake lamp switch.

DAYTIME RUNNING LAMPS

Vehicles equipped with the Daytime Running Lamps (DRL) feature illuminate the turn signal bulbs (Chrysler) or the high beam headlamp bulbs (Dodge) of both front lamp units when the engine is running, the parking brake is released, the headlamps are turned OFF and the optional automatic transmission gear selector lever is in any position except PARK. The park lamps may be ON or OFF for DRL to operate. For vehicles with a manual transmission, the DRL will operate in any transmission gear selector lever position. The TIPM must be programmed appropriately for this feature to be enabled.

Once enabled, anytime the TIPM receives electronic messages over the CAN data bus from the PCM indicating the engine is running, from the EMIC indicating the status of the left (lighting) multi-function switch is in any position except headlamps ON and the parking brake lever is released, and from the PCM indicating the automatic transmission gear selector lever is in any position except PARK, the TIPM provides a voltage output to the turn signal or high beam headlamp bulb filaments through high side drivers on the appropriate feed circuits to produce illumination.

FRONT FOG LAMPS

The front fog lamps have a path to ground at all times through their connection to the engine compartment wire harness. The engine compartment wire harness has takeouts with eyelet terminals that are secured by nuts to ground studs on the front end sheet metal within the engine compartment. The SCM monitors a hard wired multiplex input from the left multi-function switch to determine whether the fog lamps are selected, then sends an electronic front fog lamp switch status message to the EMIC over the Local Interface Network (LIN) data bus and the EMIC relays an electronic front fog lamp request message to the TIPM over the CAN data bus.

When the TIPM receives a front fog lamp request message it then controls front fog lamp operation by controlling a battery voltage output through high side drivers on right and left fog lamp feed circuits. The TIPM also sends the appropriate electronic message back to the EMIC to illuminate or extinguish the front fog lamp indicator. In certain markets where required, the TIPM will automatically de-energize the front fog lamps any time the headlamp high beams are selected.

The TIPM also provides a battery saver (load shedding) feature for the front fog lamps, which will turn these lamps OFF if they are left ON for more than about eight minutes with the ignition switch in the LOCK position, if there is a charging system failure, or if the electrical system voltage falls below about 11.75 volts for more than about 30 seconds. The TIPM will return the front fog lamps to normal operation when it detects that system voltage is greater than 13.0 volts for more than about 30 seconds.

Each front fog lamp includes an integral adjustment screw to be used for static aiming of the fog lamp beams.

HAZARD WARNING LAMPS

The hazard warning system includes the EMIC, the TIPM and the hazard switch in the switch pod located in the center stack area of the instrument panel, below the air conditioner and heater controls. The hazard switch provides a hard wired output to the TIPM. The TIPM monitors the hazard switch input through an internal pull-up.

When the TIPM receives an input from the hazard switch it controls hazard warning system operation and flash rate by controlling battery voltage outputs through high side drivers on the right and left turn signal feed circuits. The TIPM also sends the appropriate electronic messages back to the EMIC over the CAN data bus to control the illumination and flash rate of the right and left turn signal indicators, as well as to control the click rate of an electromechanical relay soldered onto the EMIC electronic circuit board that emulates the sound emitted by a conventional hazard warning flasher. The EMIC then sends messages to the instrument panel switch pod over the LIN data bus to control the illumination of the hazard switch push button.

HEADLAMPS

The headlamp system includes the SCM, the EMIC, the TIPM, and the left (lighting) multi-function switch on the steering column. The headlamp bulbs have a path to ground at all times through their connection to the engine compartment wire harness. The engine compartment harness has takeouts with eyelet terminals that are secured to the front end sheet metal within the engine compartment. The TIPM will store a Diagnostic Trouble Code (DTC) for any shorts or opens in the headlamp circuits.

The SCM monitors a hard wired multiplex input to determine the status of the left multi-function switch and whether the headlamp high or low beams are selected. The SCM then sends the appropriate electronic headlamp switch and headlamp beam select switch status messages to the EMIC over the LIN data bus. The EMIC then sends the appropriate electronic headlamp and headlamp beam request messages to the TIPM over the CAN data bus. On Chrysler models, the TIPM responds to these messages by providing a pulse width modulated voltage output to the headlamp bulbs through high side drivers on the right and left low beam feed circuits to illuminate the headlamps, and controls the high and low beam shutter operation through high side drivers on the right and left high beam feed circuits. On Dodge models, the TIPM responds to these messages by providing a pulse width modulated voltage output to the headlamps through high side drivers on the right and left low and high beam feed circuits to illuminate the selected headlamp filaments. The TIPM also sends the appropriate electronic messages to the EMIC to control the illumination of the high beam indicator. When the optical horn feature is selected, the low beams will shut OFF about 200 milliseconds after the high beams are activated.

The TIPM also remembers which beams (LOW or HIGH) were selected when the headlamps were last turned OFF, and energizes those beams again the next time the headlamps are turned ON. The TIPM provides a battery saver (load shedding) feature for the headlamps, which will turn these lamps OFF if they are left ON for more than about eight minutes with the ignition switch in the LOCK position. The SCM and the EMIC each provide a fail-safe feature for the headlamps, which will cause the TIPM to turn the low beam headlamps ON automatically if there is no input available from the left multi-function switch. The TIPM also provides a fail-safe feature for the headlamps that will turn the headlamps ON automatically whenever a loss of CAN bus communication is detected with the ignition switch in the ON position.

Each headlamp includes an integral adjustment screw (domestic markets) to be used for static aiming of the headlamps.

HEADLAMP DELAY

The headlamp delay feature includes the left (lighting) multi-function switch, the SCM, the EMIC and the TIPM. This feature has customer programmable delay intervals of 0 seconds (disabled), 30 seconds, 60 seconds and 90 seconds. If the left multi-function switch remains in the headlamp ON position until after the ignition switch is turned to the OFF position, then the headlamps will remain illuminated until after the selected delay interval has elapsed. The park lamps will not stay ON during the headlamp delay interval. The default delay interval is zero seconds (disabled), but can be reprogrammed by the customer using the customer programmable features function of the EMIC.

PARK LAMPS

The park lamps system includes the left (lighting) multi-function switch, the SCM, the EMIC and the TIPM. The front park lamps each have a path to ground at all times through their connection to the engine compartment wire harness. The engine compartment wire harness has takeouts with eyelet terminals that are secured to the front end sheet metal within the engine compartment. The rear lamp units and license plate lamp bulbs have a path to ground at all times through a takeout and eyelet terminal of the body wire harness that is secured to the body sheet metal within the passenger compartment.

The SCM monitors a hard wired multiplex input from the left multi-function switch, then sends the appropriate electronic headlamp switch status messages to the EMIC over the LIN data bus. Then the EMIC relays the appropriate electronic message to the TIPM over the CAN data bus. The TIPM responds to these messages by providing a battery voltage output to the appropriate lamps through high side drivers on the proper park lamp right and left circuits. The TIPM and the SCM also send the appropriate electronic messages to the EMIC to control the illumination and lighting level of the panel lamps.

The TIPM provides a battery saver (load shedding) feature for the park lamps, which will turn these lamps OFF if they are left ON for more than about eight minutes with the ignition switch in the LOCK position. The SCM and the EMIC each provide a fail-safe feature for the park lamps, which will send an electronic message to the TIPM to turn these lamps ON automatically if there is no input available from the left multi-function switch. The TIPM also provides a fail-safe feature for the park lamps that will turn these lamps ON automatically whenever a loss of CAN bus communication is detected with the ignition switch in the ON position.