Part 5 of 8
LOW FUEL INDICATORA low fuel indicator lamp is used only on the high-line instrument clusters. The low fuel indicator lamp is located near the lower left corner of the instrument cluster overlay, adjacent to the "Empty" graduation of the fuel gauge. The low fuel indicator lamp consists of a International Control and Display Symbol icon for "Fuel". This icon is a stenciled cutout in the opaque layer of the instrument cluster overlay. The dark outer layer of the overlay prevents the icon from being clearly visible when the lamp is not illuminated. However, an amber lens behind the cutout in the opaque layer of the overlay causes the icon to appear in amber through the translucent outer layer of the overlay when it is illuminated from behind by a replaceable incandescent bulb and bulb holder unit located on the instrument cluster electronic circuit board. The low fuel indicator lamp is serviced as a unit with the instrument cluster.
The low fuel indicator lamp gives an indication to the vehicle operator when the level of fuel in the fuel tank becomes low. This lamp is controlled by the instrument cluster circuit board based upon the cluster programming and electronic messages received by the cluster from the Powertrain Control Module (PCM) over the Chrysler Collision Detection (CCD) data bus. The low fuel indicator lamp bulb receives battery current on the instrument cluster electronic circuit board through the fused ignition switch output (st-run) circuit whenever the ignition switch is in the ON or Start positions; therefore, the lamp will always be OFF when the ignition switch is in any position except ON or Start. The lamp bulb only illuminates when it is switched to ground by the instrument cluster circuitry. The instrument cluster will turn ON the low fuel indicator lamp for the following reasons:
- Bulb Test - Each time the ignition switch is turned to the ON position the lamp is illuminated for about three seconds.
- Percent Tank Full Message - Each time the cluster receives a message from the PCM indicating that the percent tank full of the fuel tank equals about one-eighth full, the instrument cluster low fuel circuitry monitors the incoming percent tank full messages for ten seconds. If no percent tank full messages above one-eighth full are received during that ten seconds, the lamp will be illuminated. If any above one-eighth full messages are received during that monitored period, the ten second delay counter returns to zero. Once the lamp is illuminated, each time the instrument cluster low fuel circuitry receives a message indicating that the percent tank full of the fuel tank is above one-eighth full, it monitors the incoming percent tank full messages from the PCM for twenty seconds. If no percent tank full messages of one-eighth or less are received during that twenty seconds, the lamp will be turned OFF. If any one-eighth full or below messages are received during that monitored period, the twenty second delay counter returns to zero. This strategy is intended to reduce the effect that fuel sloshing within the fuel tank can have on reliable lamp indications. The lamp is also turned OFF and the delay counters are returned to zero when the ignition switch is turned to the OFF position.
- Actuator Test - Each time the cluster is put through the actuator test, the lamp will be turned ON and OFF in a prescribed sequence to confirm the functionality of the lamp and the cluster circuitry.
The PCM continually monitors the fuel tank sending unit, then sends the proper messages to the instrument cluster. If the low fuel indicator fails to light during the bulb test, replace the bulb with a known good unit. For further diagnosis of the low fuel indicator lamp or the instrument cluster circuitry that controls the lamp, (Refer to INSTRUMENT CLUSTER - DIAGNOSIS AND TESTING). For proper diagnosis of the PCM, the CCD data bus, or the message inputs to the instrument cluster that control the low fuel indicator, a DRB III scan tool and the appropriate diagnostic information are required.
LOW OIL PRESSURE INDICATOR
A low engine oil pressure warning lamp is used only in the low-line instrument clusters. The low engine oil pressure warning lamp is located on the right side of the instrument cluster overlay, above the engine coolant temperature warning lamp. The low engine oil pressure warning lamp consists of a red lens behind a round cutout in the instrument cluster overlay. An International Control and Display Symbol icon for "Engine Oil" is imprinted in black near the center of the red lens. The icon is clearly visible on the face of the instrument cluster when the lamp is not illuminated, and is silhouetted in a bright red glow when the low engine oil pressure warning lamp is illuminated from behind by a replaceable incandescent bulb and bulb holder unit located on the instrument cluster electronic circuit board. The low engine oil pressure warning lamp is serviced as a unit with the instrument cluster.
The low engine oil pressure warning lamp gives an indication to the vehicle operator when the engine oil pressure is low. This lamp is controlled by the instrument cluster circuit board based upon the cluster programming and electronic messages received by the cluster from the Powertrain Control Module (PCM) over the Chrysler Collision Detection m(CCD) data bus. The low engine oil pressure warning lamp bulb receives battery current on the instrument cluster electronic circuit board through the fused ignition switch output (st-run) circuit whenever the ignition switch is in the ON or Start positions; therefore, the lamp will always be OFF when the ignition switch is in any position except ON or Start. The lamp bulb only illuminates when it is switched to ground by the instrument cluster circuitry. The instrument cluster will turn ON the low engine oil pressure warning lamp for the following reasons:
- Bulb Test - Each time the ignition switch is turned to the ON position the lamp is illuminated for about three seconds.
- Engine Oil Pressure Low Message - Each time the cluster receives a message from the PCM indicating the engine oil pressure is about 0.003 kg/sq.cm or lower (about 6 psi or lower), the lamp will be illuminated. The lamp remains illuminated until the cluster receives a message from the PCM indicating that the engine oil pressure is about 0.004 kg/sq.cm or higher (about 8 psi or higher), or until the ignition switch is turned to the OFF position, whichever occurs first. The cluster will only turn the lamp ON in response to an engine oil pressure low message if the engine speed is 300 rpm or greater.
- Actuator Test - Each time the cluster is put through the actuator test, the lamp will be turned ON and OFF in a prescribed sequence to confirm the functionality of the lamp and the cluster circuitry.
The PCM continually monitors the engine oil pressure sensor to determine the engine oil pressure. The PCM then sends the proper engine oil pressure messages to the instrument cluster. If the low engine oil pressure warning lamp fails to light during the bulb test, replace the bulb with a known good unit. For further diagnosis of the engine oil pressure warning lamp or the instrument cluster circuitry that controls the lamp, (Refer to INSTRUMENT CLUSTER - DIAGNOSIS AND TESTING). If the instrument cluster turns ON the lamp after the bulb test, it may indicate that the engine or the engine oiling system requires service. For proper diagnosis of the engine oil pressure sensor, the CCD data bus, or the message inputs that control the low engine oil pressure warning lamp, a DRB III scan tool and the appropriate diagnostic information are required.
ODOMETER
An odometer and trip odometer are standard equipment in all instrument clusters. The odometer and trip odometer information are displayed in a common electronic Vacuum-Fluorescent Display (VFD), which is centered on the lower edge of the instrument cluster and visible through a small window cutout on the instrument cluster overlay. However, the odometer and trip odometer information are not displayed simultaneously. The trip odometer reset switch on the instrument cluster circuit board toggles the display between odometer and trip odometer modes by depressing the odometer/trip odometer switch knob that extends through the lower edge of the cluster lens, just right of center. Both the odometer and trip odometer information are stored in the instrument cluster memory.
The odometer can display values up to 999,999 kilometers (999,999 miles) before it rolls over to zero. The trip odometer can display values up to 999.9 kilometers (999.9 miles) before it rolls over to zero. The odometer display does not have a decimal point and will not show values less than a full unit (kilometer or mile), the trip odometer display does have a decimal point and will show tenths of a unit (kilometer or mile). The unit of measure for the odometer and trip odometer display is not shown in the VFD. If the instrument cluster has a speedometer with a primary scale in kilometers-per-hour, a "KM" is printed on the cluster mask next to the VFD to indicate the odometer unit of measure. During daylight hours (exterior lamps OFF) the VFD is illuminated at full brightness for clear visibility. At night (exterior lamps are ON) an Analog/Digital (A/D) converter on the instrument cluster circuit board converts the analog panel lamps dimmer rheostat input from the headlamp switch to a digital dimming level signal for controlling the lighting level of the VFD. The VFD is serviced as a unit with the instrument cluster.
The odometer and trip odometer give an indication to the vehicle operator of the distance the vehicle has traveled. This gauge is controlled by the instrument cluster circuit board based upon the cluster programming and electronic messages received by the cluster from the Powertrain Control Module (PCM) over the Chrysler Collision Detection (CCD) data bus. The odometer and trip odometer information is displayed by the instrument cluster Vacuum-Fluorescent Display (VFD), and the VFD will not display odometer or trip odometer cluster information after the ignition switch is turned to the OFF position. The instrument cluster circuitry controls the VFD and provides the following features:
- Odometer/Trip Odometer Display Toggling - Actuating the trip odometer reset switch momentarily with the ignition switch in the ON position will toggle the VFD between the odometer and trip odometer display. Each time the ignition switch is turned to the ON position the VFD will automatically return to the mode (odometer or trip odometer) last displayed when the ignition switch was turned to the OFF position.
- Trip Odometer Reset - When the trip odometer reset switch is pressed and held for longer than about two seconds will reset the trip odometer to 000.0 kilometers (miles). The VFD must be displaying the trip odometer information in order for the trip odometer information to be reset.
- Message Failure - If the cluster fails to receive a distance message during normal operation, it will hold and display the last data received until the ignition switch is turned to the OFF position. If the cluster does not receive a distance message within one second after the ignition switch is turned to the ON position, it will display the last distance message stored in the cluster memory. If the cluster is unable to display distance information due to an error internal to the cluster, the VFD display will be blank.
- Actuator Test - Each time the cluster is put through the actuator test, the VFD will display all of each number (0 through 9) in two second steps to confirm the functionality of the VFD and the cluster circuitry.
The PCM continually monitors the vehicle speed sensor, then sends the proper distance messages to the instrument cluster. For further diagnosis of the odometer/trip odometer or the instrument cluster circuitry that controls these functions, (Refer to INSTRUMENT CLUSTER - DIAGNO515 AND TESTING). For proper diagnosis of the PCM, the CCD data bus, or the message inputs to the instrument cluster that control the odometer/trip odometer, a DRB III scan tool and the appropriate diagnostic information are required.
OIL PRESSURE GAUGE
An oil pressure gauge is used only in the high-line instrument clusters. The oil pressure gauge is located on the right side of the instrument cluster, above the engine coolant temperature gauge. The oil pressure gauge consists of a movable gauge needle or pointer controlled by the instrument cluster circuitry and a fixed 90 degree scale on the cluster overlay that reads left-to-right from 0 kg/sq.cm (or 0 psi) to 5.4 kg/sq.cm (or 80 psi). An International Control and Display Symbol icon for "Engine Oil" is located on the the cluster overlay above the left end of the gauge scale. The gauge needle, gauge scale, and icon are clearly visible on the face of the instrument cluster in daylight, and are illuminated from behind by the panel lamps dimmer controlled cluster illumination lighting when the exterior lamps are turned ON. Cluster illumination is provided by replaceable incandescent bulb and bulb holder units located on the instrument cluster electronic circuit board. The oil pressure gauge is serviced as a unit with the instrument cluster.
The oil pressure gauge gives an indication to the vehicle operator of the engine oil pressure. This gauge is controlled by the instrument cluster circuit board based upon the cluster programming and electronic messages received by the cluster from the Powertrain Control Module (PCM) over the Chrysler Collision Detection (CCD) data bus. The oil pressure gauge is an air core magnetic unit that receives battery current on the instrument cluster electronic circuit board through the fused ignition switch output (st-run) circuit whenever the ignition switch is in the ON or Start positions. The cluster is programmed to move the gauge needle back to the low end of the scale after the ignition switch is turned to the OFF position. The instrument cluster circuitry controls the gauge needle position and provides the following features:
- Engine Oil Pressure Low Message - Each time the cluster receives a message from the PCM indicating the engine oil pressure is about 0.003 kg/sq.cm or lower (about 6 psi or lower), the gauge needle is moved to the far left (low) end of the gauge scale and the check gauges indicator is illuminated. The gauge needle remains and the check gauges indicator remains illuminated until the cluster receives a message from the PCM indicating that the engine oil pressure is about 0.004 kg/sq.cm or higher (about 8 psi or higher), or until the ignition switch is turned to the OFF position, whichever occurs first. The cluster will only turn the check gauges indicator lamp ON in response to an engine oil pressure low message if the engine speed is 300 rpm or greater.
- Message Failure - If the cluster fails to receive an engine oil pressure message, it will hold the gauge needle at the last indication until a new message is received, or until the ignition switch is turned to the OFF position, whichever occurs first.
- Actuator Test - Each time the cluster is put through the actuator test, the gauge needle will be swept to several calibration points on the gauge scale in a prescribed sequence to confirm the functionality of the gauge and the cluster circuitry.
The PCM continually monitors the engine oil pressure sensor to determine the engine oil pressure. The PCM then sends the proper engine oil pressure messages to the instrument cluster. For further diagnosis of the oil pressure gauge or the instrument cluster circuitry that controls the gauge, (Refer to INSTRUMENT CLUSTER - DIAGNOSIS AND TESTING). If the instrument cluster turns ON the check gauges indicator due to a low oil pressure gauge reading, it may indicate that the engine or the engine oiling system requires service. For proper diagnosis of the engine oil pressure sensor, the CCD data bus, or the message inputs to the instrument cluster that control the oil pressure gauge, a DRB III scan tool and the appropriate diagnostic information are required.