The instrument cluster scan tool data list and scan tool data definition information can assist in diagnosing instrument cluster related problems, especially when no diagnostic trouble codes (DTC) are stored in memory. A vehicle scan tool data can be compared with the scan tool data values from a known good vehicle in the scan tool data list table. When data from the vehicle is different from the typical data display value, the scan tool data definition information will help in understanding the nature of the difference and the source of the problem.
Data
Battery Voltage
Range: 9.0-19.0 Volts
This data refers to the battery system voltage that is measured by the instrument cluster.
Vehicle Speed
Range: 0-193 km/h (0-120 mph)
This is the instrument cluster's measurement of the vehicle's speed from a discrete input from the vehicle control module (VCM) or powertrain control module (PCM).
Engine Speed
Range: 0-7,000 RPM
This is the instrument cluster's measurement of the engine speed in revolutions per minute (RPM) from a discrete input from the vehicle control module (VCM) powertrain control module (PCM).
Monitored Coolant Temperature
Range: -40-215°C (-40-419°F)
The engine coolant temperature sensor monitors the engine coolant temperature and sends this information to the VCM/PCM. The VCM/PCM then sends this information to the instrument cluster over the class 2 serial data line. If a class 2 communication failure occurs, this data will be -40°.
Displayed Coolant Temperature
Range: 37.8-127°C (100-260°F)
The instrument cluster receives the engine coolant temperature information from the VCM/PCM over the class 2 serial data line. The instrument cluster then processes this information and displays it using the coolant temperature gauge. The displayed coolant temperature information refers to the information the instrument cluster is processing and attempting to display on the coolant temperature gauge. This data may be different from the monitored coolant temperature for a period of time due to filtering. The data may also be different from the monitored coolant temperature when the coolant temperature is not in the range of (37.8-127°C (100-260°F) since the display is limited to these values. If a class 2 communication failure occurs, this data will be at the minimum value of 37.8°C (100°F).
Monitored Fuel Level
Range: 0-100 percent
The fuel gauge sender monitors the level of fuel in the tank and sends this information to the VCM/PCM. The VCM/PCM then sends this information to the instrument cluster over the class 2 serial data line. If a class 2 communication failure occurs, this data will be 0.
Displayed Fuel Level
Range: 0-100 percent
The VCM/PCM receives the displayed fuel level information from the fuel gauge sender. The VCM/PCM then sends the displayed fuel level information to the instrument cluster over the class 2 serial data line. The instrument cluster then processes this information and displays it using the fuel gauge. The displayed fuel level information refers to the information the instrument cluster is processing and attempting to display on the fuel gauge. This data may be different from the monitored fuel level for a period of time due to filtering. If a class 2 communication failure occurs, this data will be 0.
Displayed Odometer
Range: 0-999,999 Kilometers/Miles
This data refers to the displayed odometer mileage on the odometer display.
Displayed Trip Odometer
Range: 0-9,999.9 Kilometers/Miles
This data refers to the displayed trip odometer mileage displayed on the trip odometer display.
Inputs
PRNDL State
Range: Park / Reverse / Neutral / Drive / Third / Second / First / Invalid
This data refers to the PRNDL position that is communicated to the instrument cluster over the class 2 serial data line by the PCM/VCM. The value of this parameter corresponds to the gear selected on the PRNDL display. The gear selected with the shift lever should have a square around the gear position in the PRNDL display. The PRNDL display can also display INVALID for a gear position. INVALID will be displayed when one of the following conditions exist:
| • | The data from the PCM/VCM is INVALID |
| • | The data from the PCM/VCM is PARK but the instrument cluster does detect a CLOSED state from the park position switch (column shift only) |
| • | The data from the PCM/VCM is not PARK but the instrument cluster does detect a CLOSED state from the park position switch (column shift only) |
| • | A class 2 communication failure has occurred between the instrument cluster and the PCM/VCM |
Park Switch
Range: Open / Closed
This data refers to the park position of the gear shift lever for column shift vehicles only. The park position switch is part of the steering column and is only on vehicles equipped with a column shift steering column.
OPEN is displayed when the gear shift lever is not in PARK.
CLOSED is displayed when the following conditions exist:
| • | The gear shift lever is in the PARK position |
| • | The gear shift lever is at the normal rest position |
| • | The park position switch is providing a ground to the instrument cluster for the park switch circuit |
Dimming
Range: Active / Inactive
This data refers to the dimming availability feature of the PRNDL and the odometer/trip odometer vacuum florescent displays.
ACTIVE is displayed when the park lamps are ON.
When ACTIVE is displayed, you may use the thumbwheel dimming switch in order to dim the following displays:
| • | The PRNDL display |
| • | The odometer/trip odometer vacuum florescent display |
INACTIVE is displayed when the Park Lamps are OFF.
When INACTIVE is displayed, you can not dim the following displays:
| • | The PRNDL display |
| • | The odometer/trip odometer vacuum florescent display |
Trip Reset Switch
Range: Active / Inactive
This data refers to the position of the trip odometer reset switch. ACTIVE is displayed when the trip reset switch is pushed in. INACTIVE is displayed when the trip reset switch is in the normal position (not pushed in).
Outputs
Check Gauges Lamp
Range: ON/ OFF
This output refers to the commanded state of the CHECK GAUGES indicator.
ON is displayed when the instrument cluster is commanding the CHECK GAUGES indicator to turn ON.
The instrument cluster will command the CHECK GAUGES indicator to turn ON when one of the following conditions exist:
| • | The instrument cluster receives a high engine coolant temperature (120°C or 248°F) from the VCM/PCM over the Class 2 data line and the engine is running. |
| • | The instrument cluster receives a low oil pressure signal (less than 5 ohms) from the oil pressure sender and the engine is running. |
| • | During the bulb check period. The bulb check will begin once the ignition switch is first turned to RUN position, and will last for 3 seconds. |
OFF is displayed when the instrument cluster is not commanding the CHECK GAUGES indicator to turn ON.
Low Fuel Lamp
Range: ON / OFF
This output refers to the commanded state of the LOW FUEL indicator. ON is displayed when the instrument cluster is commanding the LOW FUEL indicator ON. OFF is displayed when the instrument cluster is not commanding the LOW FUEL indicator ON. The instrument cluster will command the LOW FUEL indicator ON under the following conditions:
| • | When the instrument cluster receives a class 2 (percent monitored fuel level) message of less than 19.2 percent from the VCM/PCM. Once the indicator is ON, the Monitored Fuel Level must rise above 23 percent in order to turn the indicator OFF. |
| • | During the bulb check period. The bulb check will begin once the ignition switch is first turned to RUN position, and will last for 3 seconds. |
| • | A class 2 communication failure has occurred between the instrument cluster and the VCM/PCM. |
Service 4WD
Range: ON / OFF
This output refers to the commanded state of the SERVICE 4WD indicator. ON is displayed when the instrument cluster is commanding the SERVICE 4WD indicator ON. The instrument cluster commands the SERVICE 4WD indicator ON when it receives a class 2 serial data message from the automatic transfer case (ATC) module requesting the SERVICE 4WD indicator ON. OFF is displayed when the ATC module is not commanding the instrument cluster to turn the SERVICE 4WD indicator ON. The instrument cluster will also command the SERVICE 4WD indicator ON when one of the following conditions exist:
| • | The instrument cluster receives a class 2 serial data message from the ATC module indicating a 4WD malfunction |
| A class 2 communication failure has occurred between the instrument cluster and the ATC module |
| • | A DTC is set related to the 4WD system |
Overspeed Lamp
Range: ON/ OFF
This output refers to the OVERSPEED indicator.
ON is displayed when the instrument cluster is commanding the OVERSPEED indicator to FLASH because a Class 2 message is received from the VCM/PCM.
OFF is displayed when the instrument cluster is not commanding the OVERSPEED indicator to FLASH.
Anti-Lock Brake System (ABS) Lamp
Range: ON / OFF
This output refers to the commanded state of the ABS indicator. ON is displayed when the instrument cluster is commanding the ABS indicator to turn ON. OFF is displayed when the instrument cluster is not commanding the ABS indicator to turn ON. The instrument cluster will command the ABS indicator to turn ON under the following conditions:
| • | The instrument cluster receives a class 2 message from the electronic brake control module (EBCM) indicating there is a malfunction in the ABS system |
| • | During the bulb check period for 3 seconds after the ignition switch is first turned to the RUN position. |
| • | A class 2 communication failure occurs. |
| • | A diagnostic trouble code (DTC) is stored related to the system malfunction. |
Brake Lamp
Range: ON / OFF
This output refers to the commanded state of the red BRAKE indicator. ON is displayed when the instrument cluster is commanding the red BRAKE indicator to turn ON. OFF is displayed when the instrument cluster is not commanding the red BRAKE indicator to turn ON. The instrument cluster will command the red BRAKE indicator to turn ON under the following conditions:
| • | The red BRAKE indicator will FLASH when the instrument cluster receives a class 2 serial data message from the body control module (BCM) that indicates the parking brake is set. |
| • | When the instrument cluster receives a class 2 serial data message from the electronic brake control module (EBCM) indicating that there is a problem with the base brake system (non-ABS portion). |
| • | During the bulb check period. The bulb check will begin once the ignition switch is first turned to RUN position, and will last for 3 seconds. |
Fasten Seat Belts
Range: ON / OFF
This output refers to the commanded state of the fasten seat belts indicator. ON is displayed when the instrument cluster is commanding the fasten seat belts indicator to turn ON. OFF is displayed when the instrument cluster is not commanding the fasten seat belts indicator to turn ON. The instrument cluster will command the fasten seat belts indicator to turn ON under the following conditions:
| • | The fasten seat belt indicator will turn ON for 20 seconds followed by 55 seconds of FLASHING when it receives a class 2 serial data message from the body control module (BCM) that indicates the drivers seat belt is not buckled. |
| • | During the bulb check period for about 3 seconds after the ignition switch is first turned to the RUN position providing the drivers seat belt is not buckled. If the seat belt is buckled when the ignition switch is turned to the RUN position, the seat belt indicator will remain OFF. |
| • | If a class 2 communication failure occurs, the fasten seat belt indicator will turn ON for 20 seconds followed by 55 seconds of FLASHING. |
Security Lamp
Range: ON / OFF
This output refers to the commanded state of the SECURITY indicator. ON is displayed when the instrument cluster is commanding the SECURITY indicator ON. OFF is displayed when the instrument cluster is not commanding the SECURITY indicator ON. The instrument cluster will command the SECURITY indicator to turn ON under the following conditions:
| • | During the bulb check period. The bulb check will begin once the ignition switch is first turned to RUN position, and will last for 3 seconds. |
| • | When the instrument cluster receives a class 2 serial data message from the (BCM). |
| • | A class 2 communication failure occurs and the ignition switch in the RUN position. |
Upshift Lamp (Manual Transmission Vehicle Only)
Range: ON / OFF
This output refers to the commanded state of the UPSHIFT indicator. ON is displayed when the instrument cluster is commanding the UPSHIFT indicator to turn ON. OFF is displayed when the instrument cluster is not commanding the UPSHIFT indicator to turn ON. The instrument cluster will turn ON the upshift indicator when the instrument cluster receives a class 2 serial data message from the PCM/VCM.
High Beam Lamp
Range: ON / OFF
This output refers to the commanded state of the high beam lamp. ON is displayed when the instrument cluster is commanding the high beam lamp to turn ON. OFF is displayed when the instrument cluster is not commanding the high beam lamp to turn ON. The instrument cluster will turn ON the high beam lamp when the instrument cluster receives a class 2 serial data message from the body control module (BCM).
Battery
Range: ON / OFF
This output refers to the commanded state of the battery (voltage) indicator. ON is displayed when the instrument cluster is commanding the battery indicator ON. OFF is displayed when the instrument cluster is not commanding the battery indicator ON. The instrument cluster will command the battery indicator ON under the following conditions:
| • | The instrument cluster receives a class 2 serial data message from the PCM/VCM indicating that there is a charging system problem. |
| • | The ignition switch is turned to UNLOCK or RUN without the engine running. |
| • | A class 2 communication failure occurs. |
| • | During a 3 second bulb check after the engine has been started. |
Air Bag Lamp
Range: ON / OFF
This output refers to the commanded state of the Air Bag indicator. The Air Bag indicator is controlled by a class 2 serial data message from the supplemental restraint Sensing Diagnostic (SDM) module. ON is displayed when the SDM module sends a class 2 serial data message to the instrument cluster commanding the Air Bag indicator ON. OFF is displayed when the SDM module does not send a class 2 serial data message to the instrument cluster commanding the Air Bag indicator ON.
Service Engine Soon Lamp
Range: ON / OFF
This output refers to the commanded state of the Service Engine Soon indicator. The Service Engine Soon indicator is controlled by a discrete wire from the PCM/VCM. ON is displayed when the VCM/PCM grounds CKT 419. OFF is displayed when the VCM/PCM does not ground CKT 419.
