Part 2
SYSTEM OPERATIONCigar Lighter
A cigar lighter is standard equipment on this model. The cigar lighter is installed in the instrument panel accessory switch bezel, which is located near the bottom of the instrument panel center bezel area, below the heater and air conditioner controls. The cigar lighter base is secured by a snap fit within the accessory switch bezel.
The cigar lighter consists of two major components: a knob and heating element unit, and the cigar lighter base or receptacle shell. The receptacle shell is connected to ground, and an insulated contact in the bottom of the shell is connected to battery current. The cigar lighter receives battery voltage from a fuse in the junction block through the cigar lighter relay only when the ignition switch is in the Accessory or On positions. See Cigar Lighter Relay.
The knob and heating element are encased within a spring-loaded housing, which also features a sliding protective heat shield. When the knob and heating element are inserted in the receptacle shell, the heating element resistor coil is grounded through its housing to the receptacle shell. If the cigar lighter knob is pushed inward, the heat shield slides up toward the knob exposing the heating element, and the heating element extends from the housing toward the insulated contact in the bottom of the receptacle shell.
Two small spring-clip retainers are located on either side of the insulated contact inside the bottom of the receptacle shell. These clips engage and hold the heating element against the insulated contact long enough for the resistor coil to heat up. When the heating element is engaged with the contact, battery current can flow through the resistor coil to ground, causing the resistor coil to heat.
When the resistor coil becomes sufficiently heated, excess heat radiates from the heating element causing the spring-clips to expand. Once the spring-clips expand far enough to release the heating element, the spring-loaded housing forces the knob and heating element to pop back outward to their relaxed position. When the cigar lighter knob and element are pulled out of the receptacle shell, the protective heat shield slides downward on the housing so that the heating element is recessed and shielded around its circumference for safety.
The cigar lighter knob and heating element are available for service. The cigar lighter receptacle is serviced only as a part of the accessory switch bezel unit. If the cigar lighter base is faulty or damaged, the accessory switch bezel must be replaced.
Cigar Lighter Relay
The cigar lighter relay is a International Standards Organization (ISO)-type relay. The cigar lighter relay is a electromechanical device that switches fused battery current to the cigar lighter when the ignition switch is turned to the Accessory or On positions.
The cigar lighter relay is located in the junction block, on the right cowl side panel below the instrument panel in the passenger compartment. The cigar lighter relay cannot be repaired and, if faulty or damaged, it must be replaced.
Cluster Illumination Lamps
The cluster illumination lamps are hard-wired in the instrument cluster. When the park or head lamps are turned on, the cluster illumination lamps light. Illumination brightness is adjusted by rotating the headlamp switch knob (clockwise to dim, counter-clockwise to brighten). The instrument cluster illumination lamps receive battery feed from the panel dimmer rheostat in the headlamp switch through a fuse in the junction block.
Each of the illumination lamps is located on the instrument cluster circuit board. Each lamp has a replaceable bulb and bulb holder.
Coolant Temperature Warning Lamp
The coolant temperature warning lamp gives an indication when the engine coolant temperature is high. The lamp is turned on by the instrument cluster circuitry for about three seconds after the ignition switch is turned to the On position as a bulb test. After the bulb test, the lamp is controlled by the instrument cluster circuitry based upon an engine coolant temperature message received from the Powertrain Control Module (PCM) on the Chrysler Collision Detection (CCD) data bus.
The PCM uses an input from the engine coolant temperature sensor and internal programming to decide what engine coolant temperature message is required. The PCM then sends the proper message to the instrument cluster on the CCD data bus. If the PCM message indicates that coolant temperature is high, the instrument cluster circuitry turns on the coolant temperature warning lamp and generates a single chime tone.
The engine coolant temperature sensor is installed in a threaded hole that penetrates a coolant passage of the engine. It is a thermistor-type sensor that changes its internal resistance with changes in engine coolant temperature.
Cruise-On Indicator Lamp
The cruise-on indicator lamp gives an indication when the vehicle speed control system is turned on, even when the system is not currently engaged. The lamp is controlled by the instrument cluster circuitry based upon a message received from the Powertrain Control Module (PCM) on the Chrysler Collision Detection (CCD) data bus.
The PCM uses an input from the analog resistor- multiplexed vehicle speed control switches in the steering wheel to decide whether to turn the lamp on or off. The PCM then sends the proper message to the instrument cluster on the CCD data bus. Refer to Powertrain Management/Computer and Control System/Vehicle Speed Control System for more information.
Four-Wheel Drive Indicator Lamp
Part Time
On vehicles with the optional Command-Trac four-wheel drive system, the Part Time indicator lamp lights when the transfer case is engaged in the 4H or 4L positions. On vehicles with the optional Select-Trac four-wheel drive system, the Part Time indicator lamp lights when the transfer case is engaged in the 4 X 4 Part Time or 4 Lo positions.
When the ignition switch is in the On position, battery voltage is supplied to one side of the indicator lamp bulb. A normally-open, plunger-type, four-wheel drive switch threaded into the transfer case is hard- wired in series between the other side of the indicator lamp bulb and ground. When the transfer case is shifted into the proper position, the plunger of the four-wheel drive switch is moved, closing the switch and providing a path to ground. This causes the Part Time indicator lamp bulb to light.
Full Time
The Full Time indicator lamp is only operational on vehicles equipped with the optional Select-Trac four-wheel drive system. The Full Time indicator lamp lights when the transfer case is engaged in the 4 X 4 Full Time position.
When the ignition switch is in the On position, battery voltage is supplied to one side of the indicator lamp bulb. A normally-open, plunger-type, four-wheel drive switch threaded into the transfer case is hard-wired in series between the other side of the indicator lamp bulb and ground. When the transfer case is shifted into the proper position, the plunger of the four-wheel drive switch is moved, closing the switch and providing a path to ground. This causes the Full time indicator lamp bulb to light.
Headlamp High Beam Indicator Lamp
The headlamp high beam indicator lamp gives an indication when the headlamp high beams are turned on. The lamp is controlled by a hard-wired input from the headlamp dimmer (multi-function) switch.
One side of the indicator bulb is grounded at all times. The other side of the bulb receives a battery feed through the contacts of the dimmer switch when the multi-function switch stalk is actuated to turn on the headlamp high beams. Refer to Lighting and Horns for more information.
Low Fuel Warning Lamp
The low fuel warning lamp gives an indication when the fuel level in the fuel tank has fallen below about one-eighth of a full tank, as registered on the fuel gauge. The instrument cluster circuitry lights the lamp for about three seconds when the ignition switch is turned to the On position as a bulb test. After the bulb test, the instrument cluster circuitry controls the lamp based upon a fuel level message received from the Powertrain Control Module (PCM) on the Chrysler Collision Detection (CCD) data bus.
The PCM uses an input from the fuel gauge sending unit and internal programming to decide what fuel level message is required. The PCM then sends the proper message to the instrument cluster on the CCD data bus. If the PCM message indicates that the fuel level is below one-eighth of a full tank for more than ten seconds, the instrument cluster circuitry turns on the low fuel warning lamp and generates a single chime tone. Once the lamp is turned on, an increase in the fuel level message of at least one full needle width for more than twenty seconds is required before the cluster will turn the lamp off.
The fuel gauge sending unit is mounted to the electric fuel pump module inside the fuel tank. The sending unit has a float attached to the end of a swing-arm. The float moves up or down within the fuel tank as the fuel level changes. As the float moves, an electrical contact on the pivot end of the swing-arm wipes across a resistor coil, which changes the resistance of the sending unit.
Low Oil Pressure Warning Lamp
The low oil pressure warning lamp gives an indication when the engine oil pressure is low. The lamp is turned on by the instrument cluster circuitry for about three seconds after the ignition switch is turned to the On position as a bulb test. After the bulb test, the lamp is controlled by the instrument cluster circuitry based upon an engine oil pressure message received from the Powertrain Control Module (PCM) on the Chrysler Collision Detection (CCD) data bus.
The PCM uses an input from the engine oil pressure sensor and internal programming to decide what engine oil pressure message is required. The PCM then sends the proper message to the instrument cluster on the CCD data bus. If the PCM message indicates that oil pressure is low, the instrument cluster circuitry turns on the low oil pressure warning lamp.
The engine oil pressure sensor is installed in a threaded hole that penetrates an oil passage of the engine. The engine oil pressure sensor contains a flexible diaphragm and a variable resistor coil. The diaphragm moves in response to changes in the engine oil pressure, which changes the internal electrical resistance of the sensor.
Low Washer Fluid Warning Lamp
The low washer fluid warning lamp gives an indication when the fluid level in the washer fluid reservoir is too low. The instrument cluster circuitry controls the lamp based upon a hard-wired input from the washer fluid level sensor.
The washer fluid level sensor uses a float in the reservoir to monitor the fluid level. The up and down action of the float opens or closes the switch within the washer fluid level sensor that provides a ground signal to the instrument cluster circuitry.
If the instrument cluster circuitry senses a ground input from the washer fluid level sensor for more than about thirty seconds, it turns on the low washer fluid warning lamp. If the instrument cluster circuitry senses an open circuit from the washer fluid level sensor for more than about thirty seconds, it turns off the low washer fluid warning lamp. This helps to reduce the effects of fluid sloshing within the reservoir.
Malfunction Indicator Lamp
The Check Engine or Malfunction Indicator Lamp (MIL) gives an indication when the Powertrain Control Module (PCM) has recorded a Diagnostic Trouble Code (DTC) for an On-Board Diagnostics II (OBDII) emissions-related circuit or component malfunction. The lamp is controlled by the instrument cluster circuitry based upon messages received from the PCM on the Chrysler Collision Detection (CCD) data bus. The PCM sends a lamp-on message for about three seconds when the ignition switch is turned to the On position as a bulb test.
Following the bulb test, the PCM uses inputs from many emissions-related circuits and sensors, along with its internal programming, to decide whether a condition exists that requires the MIL lamp to be turned on. The PCM then sends the proper message to the instrument cluster on the CCD data bus to turn the lamp on or off.
The MIL lamp can also be used to display a stored DTC by flashing on and off. Refer to Powertrain Management/Computer and Control Systems for more information on the PCM or the PCM inputs. Refer to Powertrain Management/Computer and Control Systems for more information on DTCs and their retrieval.
Power Outlet
An accessory power outlet is standard equipment on this model. The power outlet is installed in the instrument panel accessory switch bezel, which is located near the bottom of the instrument panel center bezel area, below the heater and air conditioner controls. A plastic protective cap snaps into the power outlet base when the power outlet is riot being used.
The power outlet base or receptacle shell is connected to ground, and an insulated contact in the bottom of the shell is connected to battery current. The power outlet receives battery voltage from a fuse in the junction block at all times.
While the power outlet is very similar to a cigar lighter base unit, it does not include the two small spring-clip retainers inside the bottom of the receptacle shell that are used to secure the cigar lighter heating element to the insulated contact. The power outlet base is secured by a snap fit within the accessory switch bezel.
The accessory power outlet protective cap is available for service. The power outlet receptacle is serviced only as a part of the accessory switch bezel unit. If the power outlet base is faulty or damaged, the accessory switch bezel must be replaced.
Seat Belt Reminder Lamp
The seat belt reminder lamp gives a visual reminder to the vehicle occupants to fasten their seat belts. The lamp is turned on by the instrument cluster circuitry for about seven seconds when the ignition switch is turned to the On position.
The instrument cluster also receives a hard-wired input from the driver seat belt switch. If the driver seat belt switch is closed (seat belt is not buckled) when the ignition switch is turned to the On position, the instrument cluster will generate a chime warning for the duration of the seat belt reminder lamp illumination. The chime warning will stop when the driver seat belt switch is open (seat belt is buckled). If the driver seat belt switch is open (seat belt is buckled) when the ignition switch is turned to the On position, no chime tone will sound.
Turn Signal Indicator Lamps
The left and right turn signal indicator lamps give an indication when the turn signal circuits are activated. The lamps are hard-wired in the instrument cluster, and are completely controlled by the turn signal and hazard warning (multi-function) switches.
The indicator lamps are grounded at all times and receive battery feed through the contacts of the multi-function switch when the turn signal lever (multi-function switch stalk) or hazard warning button are actuated to the On position. The instrument cluster circuitry does not perform a bulb test of these lamps.
The turn signal indicator lamps are located in the instrument cluster. They flash with the exterior turn signal lamps to give the driver a visual indication that a turn signal or the hazard warning system is operating.
Upshift Indicator Lamp
Vehicles equipped with a manual transmission have an upshift indicator lamp. The upshift indicator lamp gives an indication when the driver should shift to the next highest gear for the best fuel economy. The lamp is controlled by the instrument cluster circuitry based upon a message received from the Powertrain Control Module (PCM) on the Chrysler Collision Detection (CCD) data bus.
The PCM uses inputs from many sensors and its internal programming to decide whether the engine speed and load conditions are correct for a transmission upshift. The PCM then sends the proper message to the instrument cluster on the CCD data bus to turn the lamp on or off. The PCM will send a lamp-off message three to five seconds after a lamp-on message, if an upshift is not performed. The lamp will then remain off until the vehicle stops accelerating and is brought back into the range of lamp operation, or until the transmission is shifted into another gear. If the instrument cluster circuitry receives no lamp-off messages from the PCM following a lamp-on message, the cluster will keep the lamp turned on until the ignition switch is turned to the Off position.
Voltage Warning Lamp
The voltage warning lamp gives an indication when the electrical system voltage is too low or too high. The lamp is turned on by the instrument cluster circuitry for about three seconds after the ignition switch is turned to the On position as a bulb test After the bulb test, the lamp is controlled by the instrument cluster circuitry based upon a system voltage message received from the Powertrain Control Module (PCM) on the Chrysler Collision Detection (CCD) data bus.
The PCM uses an input from the electrical system and internal programming to decide what system voltage message is required. The PCM then sends the proper message to the instrument cluster on the CCD data bus. If the PCM message indicates that the charging system is too low or too high, the instrument cluster circuitry turns on the voltage warning lamp.
Instrument Cluster
The instrument cluster is an electromechanical unit that contains integrated circuitry and internal programming to perform a variety of functions. The instrument cluster circuitry monitors hard-wired switch inputs, as well as message inputs received from other vehicle electronic control modules on the Chrysler Collision Detection (CCD) data bus network.
The instrument cluster uses these many inputs along with its internal programming and integral timer and logic circuitry to perform the functions of the rear window defogger timer on this model. The instrument cluster circuitry also has a self-diagnostic capability.
However, there are no diagnostics available for the rear window defogger timer and logic circuitry. Therefore, the diagnosis for this system consists of confirming the presence of a rear window defogger switch input signal at the instrument cluster connector, and the resulting rear window defogger relay control output signal at the defogger relay. For diagnosis of the CCD data bus and the data bus message inputs, a DRB scan tool and the proper Diagnostic Procedures are recommended.
The rear window defogger timer and logic circuitry cannot be adjusted or repaired and, if faulty or damaged, the instrument cluster assembly must be replaced.