Part 4 of 8
ENGINE TEMPERATURE LAMPAn engine coolant temperature warning lamp is used only in the low-line instrument clusters. The engine coolant temperature warning lamp is located in the right lower quadrant of the instrument cluster overlay, below the oil pressure warning lamp. The engine coolant temperature 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 Coolant Temperature" 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 engine coolant temperature warning lamp is illuminated from behind by a replaceable incandescent bulb and bulb holder unit located on the instrument cluster electronic circuit board. The engine coolant temperature warning lamp is serviced as a unit with the instrument cluster.
The engine coolant temperature warning lamp gives an indication to the vehicle operator when the engine coolant temperature is high. 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 engine coolant temperature 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 engine coolant temperature 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 Temperature High Message - Each time the cluster receives a message from the PCM indicating the engine coolant temperature is about 124 °C or higher (about 255 °F or higher), the lamp will be illuminated. The lamp remains illuminated until the cluster receives a message from the PCM indicating that the engine temperature is about 122 °C or lower (about 252 °F or lower), 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 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 coolant temperature sensor to determine the engine operating temperature. The PCM then sends the proper engine coolant temperature messages to the instrument cluster. If the engine coolant temperature warning lamp fails to light during the bulb test, replace the bulb with a known good unit. For further diagnosis of the engine coolant temperature 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 cooling system requires service. For proper diagnosis of the engine coolant temperature sensor, the CCD data bus, or the message inputs to the instrument cluster that control the engine coolant temperature warning lamp, a DRB III scan tool and the appropriate diagnostic information are required.
FUEL GAUGE
A fuel gauge is standard equipment in all instrument clusters. In the low-line instrument cluster the fuel gauge is located just to the left of center in the instrument cluster. In the high-line instrument cluster the fuel gauge is located in the left lower quadrant of the instrument cluster, below the voltmeter. The fuel 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 E (or Empty) to F (or Full). An International Control and Display Symbol icon for "Fuel" is located on the cluster overlay just below the center of the low-line cluster gauge scale, or just below the left end of the high-line cluster 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 fuel gauge is serviced as a unit with the instrument cluster.
The fuel gauge gives an indication to the vehicle operator of the level of fuel in the fuel tank. 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 fuel 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:
- Less Than Empty Percent Tank Full Message - Each time the cluster receives a message from the PCM indicating the percent tank full is less than empty, the gauge needle is moved to the far left (low) end of the gauge scale. This message would indicate that the fuel tank sender input to the PCM is a short circuit.
- More Than Full Percent Tank Full Message - Each time the cluster receives a message from the PCM indicating the percent tank full is more than full, the gauge needle is moved to the far left (low) end of the gauge scale. This message would indicate that the fuel tank sender input to the PCM is an open circuit.
- One-Eighth Percent Tank Full Message - For the high-line cluster only, 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 indicator 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 low fuel indicator lamp will be illuminated and a single chime tone is sounded. The chime tone feature will occur only once per ignition cycle. 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 indicator 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.
- Message Failure - If the cluster fails to receive a percent tank full 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 fuel tank sending unit, then sends the proper messages to the instrument cluster. For further diagnosis of the fuel gauge or the instrument cluster circuitry that controls the gauge, (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 fuel gauge, a DRB III scan tool and the appropriate diagnostic information are required.
HIGH BEAM INDICATOR
A headlamp high beam indicator lamp is standard equipment on all instrument clusters. The high beam indicator lamp is located near the upper edge of the instrument cluster overlay, in the center of the cluster. The high beam indicator lamp consists of a International Control and Display Symbol icon for "High Beam". 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, a blue lens behind the cutout in the opaque layer of the overlay causes the icon to appear in blue 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 headlamp high beam indicator lamp is serviced as a unit with the instrument cluster.
The headlamp high beam indicator lamp gives an indication to the vehicle operator that the high beams of the headlights have been selected. This lamp is hard wired on the instrument cluster electronic circuit board, and is controlled by a headlamp beam select switch input to the cluster. The headlamp high beam indicator lamp bulb is grounded on the instrument cluster electronic circuit board at all times and receives battery current whenever the headlamps are turned ON and the headlamp high beams are selected; therefore, the lamp can be ON regardless of the ignition switch position. The headlamp high beam select switch is integral to the left multi-function switch on the steering column, and is connected in series between the headlamp switch and the headlamp high beam indicator lamp. (Refer to LAMPS/LIGHTING - EXTERIOR/MULTI-FUNCTION SWITCH - OPERATION). The high beam indicator lamp can be diagnosed using conventional diagnostic tools and methods.
LIFTGATE AJAR INDICATOR
A liftgate ajar indicator lamp is standard equipment on all instrument clusters. The liftgate ajar indicator lamp is located near the lower edge of the instrument cluster overlay, to the left of the odometer/trip odometer Vacuum-Fluorescent Display (VFD). The liftgate ajar indicator lamp consists of a stenciled cutout of the International Control and Display Symbol icon for "Rear Hood (Deck Lid)" in the opaque layer of the instrument cluster overlay. The dark outer layer of the overlay prevents the indicator 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 liftgate ajar indicator lamp is serviced as a unit with the instrument cluster.
The liftgate ajar indicator lamp gives an indication to the vehicle operator that the liftgate is open or the liftgate latch is not fully engaged. This lamp is hard wired on the instrument cluster electronic circuit board, and is controlled by a liftgate ajar switch input to the cluster. The liftgate ajar indicator lamp bulb receives battery current on the instrument cluster electronic circuit hoard 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 liftgate ajar switch is connected in series between ground and the liftgate ajar switch sense input to the instrument cluster. The liftgate ajar indicator lamp can be diagnosed using conventional diagnostic tools and methods.