Part 8B

SPEEDOMETER
A speedometer is standard equipment on all instrument clusters. The speedometer is located next to the tachometer, just to the right of center in the instrument cluster. The speedometer consists of a movable gauge needle or pointer controlled by the instrument cluster circuitry and a fixed 210 degree primary scale on the gauge dial face that reads left-to-right either from 0 to 120 mph, or from 0 to 200 kph, depending upon the market for which the vehicle is manufactured. Each version also has a secondary inner scale on the gauge dial face that provides the equivalent opposite units from the primary scale. Text appearing on the cluster overlay just above the hub of the speedometer needle abbreviates the unit of measure for the primary scale in all upper case letters (i.e.: MPH or KPH), followed by the unit of measure for the secondary scale in all lower case letters (i.e.: mph or kph). The speedometer graphics are white (primary scale) and red (secondary scale) against a black field, making them clearly visible within the instrument cluster in daylight. When illuminated from behind by the panel lamps dimmer controlled cluster illumination lighting with the exterior lamps turned ON, the white graphics appear blue-green and the red graphics appear red. The orange gauge needle is internally illuminated. Gauge illumination is provided by replaceable incandescent bulb and bulb holder units located on the instrument cluster electronic circuit board. The speedometer is serviced as a unit with the instrument cluster.

The speedometer gives an indication to the vehicle operator of the vehicle road speed. This gauge is controlled by the instrument cluster circuit board based upon cluster programming and electronic messages received by the cluster from the Powertrain Control Module (PCM) over the Programmable Communications Interface (PCI) data bus. The speedometer is an air core magnetic unit that receives battery current on the instrument cluster electronic circuit board through the fused ignition switch output (run-start) 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:

- Message Failure - If the cluster fails to receive a speedometer message, it will hold the gauge needle at the last indication for about four seconds, or until the ignition switch is turned to the OFF position, whichever occurs first. If a new speedometer message is not received after about four seconds, the gauge needle will return to the far left (low) end of the scale.

- 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 in order to confirm the functionality of the gauge and the cluster control circuitry.

The PCM continually monitors the vehicle speed sensor to determine the vehicle road speed, then sends the proper vehicle speed messages to the instrument cluster. For further diagnosis of the speedometer or the instrument cluster circuitry that controls the gauge, (Refer to INSTRUMENT CLUSTER - DIAGNOSIS AND TESTING). For proper diagnosis of the vehicle speed sensor, the PCM, the PCI data bus, or the message inputs to the instrument cluster that control the speedometer, a DRB III scan tool is required. Refer to the appropriate diagnostic information.

TACHOMETER
A tachometer is standard equipment on all instrument clusters. The tachometer is located to the left of the speedometer, just to the left of center in the instrument cluster. The tachometer consists of a movable gauge needle or pointer controlled by the instrument cluster circuitry and a fixed 210 degree scale on the gauge dial face that reads left-to-right from 0 to 7. The text "RPM X 1000" imprinted on the cluster overlay directly above the hub of the tachometer needle identifies that each number on the tachometer scale is to be multiplied by 1000 rpm. The tachometer graphics are white against a black field, making them clearly visible within the instrument cluster in daylight. When illuminated from behind by the panel lamps dimmer controlled cluster illumination lighting with the exterior lamps turned ON, the white graphics appear blue-green. The orange gauge needle is internally illuminated. Gauge illumination is provided by replaceable incandescent bulb and bulb holder units located on the instrument cluster electronic circuit board. The tachometer is serviced as a unit with the instrument cluster.

The tachometer gives an indication to the vehicle operator of the engine speed. This gauge is controlled by the instrument cluster circuit board based upon cluster programming and electronic messages received by the cluster from the Powertrain Control Module (PCM) over the Programmable Communications Interface (PCI) data bus. The tachometer is an air core magnetic unit that receives battery current on the instrument cluster electronic circuit board through the fused ignition switch output (run-start) 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:

- Message Failure - If the cluster fails to receive an engine speed message, it will hold the gauge needle at the last indication for about four seconds, or until the ignition switch is turned to the OFF position, whichever occurs first. If a new engine speed message is not received after about four seconds, the gauge needle will return to the far left (low) end of the scale.

- 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 in order to confirm the functionality of the gauge and the cluster control circuitry.

The PCM continually monitors the crankshaft position sensor to determine the engine speed, then sends the proper engine speed messages to the instrument cluster. For further diagnosis of the tachometer or the instrument cluster circuitry that controls the gauge, (Refer to INSTRUMENT CLUSTER - DIAGNOSIS AND TESTING). For proper diagnosis of the crankshaft position sensor, the PCM, the PCI data bus, or the message inputs to the instrument cluster that control the tachometer, a DRB III scan tool is required. Refer to the appropriate diagnostic information.

TRANSMISSION TEMP INDICATOR
A transmission over-temperature indicator lamp is standard equipment on all instrument clusters. The transmission over-temperature indicator is located in the Information Center area of the instrument cluster, to the left of center. The transmission over-temperature indicator consists of a stencilled cutout of the words "TRANS TEMP" in the opaque layer of the instrument cluster overlay. The dark outer layer of the overlay prevents the indicator from being clearly visible when it is not illuminated. A red lens behind the cutout in the opaque layer of the overlay causes the "TRANS TEMP" text to appear in red through the translucent outer layer of the overlay when the indicator is illuminated from behind by a Light Emitting Diode (LED) soldered onto the instrument cluster electronic circuit board. The transmission overtemperature indicator is serviced as a unit with the instrument cluster.

The transmission over-temperature indicator gives an indication to the vehicle operator when the trans- mission fluid temperature is excessive, which may lead to accelerated transmission component wear or failure. This indicator is controlled by a transistor on the instrument cluster circuit board based upon cluster programming and electronic messages received by the cluster from the Powertrain Control Module (PCM) over the Programmable Communications Interface (PCI) data bus. The transmission over-temperature indicator Light Emitting Diode (LED) receives battery current on the instrument cluster electronic circuit board through the fused ignition switch output (run-start) circuit whenever the ignition switch is in the ON or Start positions; therefore, the LED will always be OFF when the ignition switch is in any position except ON or Start. The LED only illuminates when it is provided a path to ground by the instrument cluster transistor. The instrument cluster will turn ON the transmission over-temperature indicator for the following reasons:

- Bulb Test - Each time the ignition switch is turned to the ON position the transmission over-temperature indicator is illuminated for about two seconds as a bulb test.

- Trans Over-Temp Lamp-On Message - Each time the cluster receives a trans over-temp lamp-ON message from the PCM indicating that the transmission fluid temperature is 135 °C (275 °F) or higher, the indicator will be illuminated and a single chime tone is sounded. The lamp remains illuminated until the cluster receives a trans over-temp lamp-off message from the PCM, or until the ignition switch is turned to the OFF position, whichever occurs first. The chime tone feature will only repeat during the same ignition cycle if the transmission over-temperature indicator is cycled OFF and then on again by the appropriate trans over-temp messages from the PCM.

- Actuator Test - Each time the cluster is put through the actuator test, the indicator will be turned ON, then OFF again during the bulb check portion of the test to confirm the functionality of the LED and the cluster control circuitry.

The PCM continually monitors the transmission temperature sensor to determine the transmission operating condition, then sends the proper messages to the instrument cluster. If the instrument cluster turns ON the transmission over-temperature indicator due to a high transmission oil temperature condition, it may indicate that the transmission and/or the transmission cooling system are being overloaded or that they require service. For further diagnosis of the transmission over-temperature indicator or the instrument cluster circuitry that controls the LED, (Refer to INSTRUMENT CLUSTER - DIAGNOSIS AND TESTING). For proper diagnosis of the transmission temperature sensor, the PCM, the PCI data bus, or the message inputs to the instrument cluster that control the transmission over-temperature indicator, a DRB III scan tool is required. Refer to the appropriate diagnostic information.

TURN SIGNAL INDICATOR
Two turn signal indicators, one right and one left, are standard equipment on all instrument clusters. The turn signal indicators are located near the upper edge of the instrument cluster overlay, between the speedometer and the tachometer. Each turn signal indicator consists of a stenciled cutout of the International Control and Display Symbol icon for "Turn Warning" in the opaque layer of the instrument cluster overlay. The dark outer layer of the overlay prevents these icons from being clearly visible when their lamps are not illuminated. The icons appear in green through the translucent outer layer of the overlay when the indicator is illuminated from behind by a replaceable incandescent bulb and bulb holder unit located on the instrument cluster electronic circuit board. The turn signal indicators are serviced as a unit with the instrument cluster.

The turn signal indicators give an indication to the vehicle operator that the turn signal (left or right indicator flashing) or hazard warning (both left and right indicators flashing) have been selected. These indicators are controlled by two individual hard wired inputs to the instrument cluster electronic circuit board. The turn signal indicator bulbs are grounded on the instrument cluster electronic circuit board at all times. The turn signal indicator bulbs only illuminate when they are provided with battery current by the turn signal and hazard warning circuitry of the combination flasher through separate left and right turn signal circuit inputs to the instrument cluster; therefore, these indicators can be illuminated, regardless of the ignition switch position.

The turn signal indicators are connected in series between ground and the output of the combination flasher circuitry, but in parallel with the other turn signal circuits. This arrangement allows the turn signal indicators to remain functional regardless of the condition of the other circuits in the turn signal and hazard warning system. For more information on the turn signal and hazard warning system, (Refer to LIGHTING - TURN SIGNAL & HAZARD WARNING SYSTEM). The turn signal indicators can be diagnosed using conventional diagnostic tools and methods.

VOLTAGE GAUGE
A voltage gauge is standard equipment on all instrument clusters. The voltage gauge is located in the upper left quadrant of the instrument cluster, above the temperature gauge. The voltage 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 "L" (or Low) to "H" (or High). An International Control and Display Symbol icon for "Battery Charging Condition" is located on the cluster overlay, in the center of the gauge directly above the hub of the gauge needle. The voltage gauge graphics are white against a black field except for a single red graduation at each end of the gauge scale, making them clearly visible within the instrument cluster in daylight. When illuminated from behind by the panel lamps dimmer controlled cluster illumination lighting with the exterior lamps turned ON, the white graphics appear blue-green and the red graphics appear red. The orange gauge needle is internally illuminated. Gauge illumination is provided by replaceable incandescent bulb and bulb holder units located on the instrument cluster electronic circuit board. The voltage gauge is serviced as a unit with the instrument cluster.

The voltage gauge gives an indication to the vehicle operator of the electrical system voltage. This gauge is controlled by the instrument cluster circuit board based upon cluster programming and electronic messages received by the cluster from the Powertrain Control Module (PCM) over the Programmable Communications Interface (PCI) data bus. The voltage gauge is an air core magnetic unit that receives battery current on the instrument cluster electronic circuit board through the fused ignition switch output (run-start) 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:

- Charge Fail Message - Each time the cluster receives a message from the PCM indicating a charge fail condition (system voltage is 10.8 volts or lower), the gauge needle is moved to the "L" graduation on the gauge scale and the check gauges indicator is illuminated. The gauge needle remains on the "L" graduation and the check gauges indicator remains illuminated until the cluster receives a message from the PCM indicating there is no charge fail condition (system voltage is 10.9 volts or higher, but lower than 16.7 volts), or until the ignition switch is turned to the OFF position, whichever occurs first.

- Voltage High Message - Each time the cluster receives a message from the PCM indicating a voltage high condition (system voltage is 16.7 volts or higher), the gauge needle is moved to the "H" graduation on the gauge scale and the check gauges indicator is illuminated. The gauge needle remains on the "H" graduation and the check gauges indicator remains illuminated until the cluster receives a message from the PCM indicating there is no voltage high condition (system voltage is 16.6 volts or lower, but higher than 10.9 volts), or until the ignition switch is turned to the OFF position, whichever occurs first.

- Message Failure - If the cluster fails to receive a system voltage 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 in order to confirm the functionality of the gauge and the cluster control circuitry.

The PCM continually monitors the system voltage to control the generator output. The PCM then sends the proper system voltage messages to the instrument cluster. For further diagnosis of the voltage 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 charge fail or voltage high condition, it may indicate that the charging system requires service. For proper diagnosis of the charging system, the PCI data bus, or the message inputs to the instrument cluster that control the voltage gauge, a DRB III scan tool is required. Refer to the appropriate diagnostic information.

WASHER FLUID INDICATOR
A washer fluid indicator is standard equipment on all instrument clusters. The washer fluid indicator is located in the Information Center area of the instrument cluster to the right of center. The washer fluid indicator consists of a stenciled cutout of the International Control and Display Symbol icon for "Windshield Washer Fluid" in the opaque layer of the instrument cluster overlay. The dark outer layer of the overlay prevents the indicator from being clearly visible when it is not illuminated. 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 Light Emitting Diode (LED) soldered onto the instrument cluster electronic circuit board. The washer fluid indicator is serviced as a unit with the instrument cluster.

The washer fluid indicator gives an indication to the vehicle operator when the fluid level in the washer fluid reservoir is low. This indicator is controlled by a transistor on the instrument cluster electronic circuit board based upon cluster programming and a hard wired washer fluid level switch input to the cluster. The washer fluid indicator Light Emitting Diode (LED) receives battery current on the instrument cluster electronic circuit board through the fused ignition switch output (run-start) circuit whenever the ignition switch is in the ON or Start positions; therefore, the indicator will always be OFF when the ignition switch is in any position except ON or Start. The LED only illuminates when it is provided a path to ground by the instrument cluster transistor. The instrument cluster will turn ON the washer fluid indicator for the following reasons:

- Bulb Test - Each time the ignition switch is turned to the ON position the indicator is illuminated for about two seconds as a bulb test.

- Washer Fluid Level Switch Input - Immediately after the bulb test, if the cluster senses ground on the washer fluid switch sense circuit for more than about thirty seconds, it turns ON the washer fluid indicator. Any time after the bulb test, the cluster must sense ground on the washer fluid switch sense circuit for more than about sixty seconds before it turns ON the indicator. Once illuminated, the indicator will remain illuminated until the ignition switch is cycled and the cluster senses an open circuit on the low washer fluid sense input. This strategy is intended to reduce the effect that fluid sloshing within the washer reservoir can have on reliable indicator operation.

- Actuator Test - Each time the cluster is put through the actuator test, the indicator will be turned ON, then OFF again during the bulb check portion of the test to confirm the functionality of the LED and the cluster control circuitry.

The washer fluid level switch is connected in series between ground and the washer fluid switch sense input to the instrument cluster. For more information on the washer fluid level switch, (Refer to WASHER FLUID LEVEL SWITCH - OPERATION). For further diagnosis of the washer fluid indicator or the instrument cluster circuitry that controls the indicator, (Refer to INSTRUMENT CLUSTER - DIAGNOSIS AND TESTING). The washer fluid level switch input to the cluster can be diagnosed using conventional diagnostic tools and methods.