Scan Tool Data Definitions. Chevrolet Chevy C Silverado

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 1999 🢒 Chevy C Silverado - 2WD 🢒 Body and Accessories 🢒 Instrument Panel, Gauges, and Console 🢒 Scan Tool Data Definitions

The instrument cluster scan tool data display values and 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 data display values from a known good vehicle in the scan tool data display table. When data from the vehicle differs from the typical data display value, the 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 as measured by the instrument panel cluster (IPC).

Vehicle Speed -- Range: 0 MPH - 120 MPH (0 KM/H - 193 KM/H): This is the cluster 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 RPM- 7,000 RPM: This is the cluster 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°F-419°F (-40°C- 215°C): This data is the clusters measurement of the engine coolant temperature as provided by the VCM/PCM on the class 2 serial data line. If a class 2 communication failure occurs, this data will be -40°.

Displayed Coolant Temperature - Range: 89°F - 260°F (32°C- 127°C): This data is the coolant temperature the IPC is attempting to display on the coolant temperature gauge. This data may differ from the monitored coolant temperature for a period of time due to filtering. The data may also differ from the monitored coolant temperature when coolant temperature is not in the range of 160°F - 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 89°F.

Monitored Trans Oil Temperature - Range: -40°F- 419°F (-40°C - 215°C): This data is the cluster's measurement of the trans oil temperature as provided by the VCM/PCM on the class 2 serial data line. If a class 2 communication failure occurs, this data will be -40°F or -40°C.

Displayed Trans Oil Temperature- Range: 84°F- 315°F (29°C- 157°C): This data is the trans oil temperature the instrument panel cluster (IPC) receives from the VCM/PCM and attempting to display on the trans oil temperature gauge. This data may differ from the monitored trans oil temperature for a period of time due to filtering. The data may also differ from the monitored trans oil temperature when trans oil temperature is not in the range of 100°F - 300°F since the display is limited to these values. If a class 2 communication failure occurs, this data will be at 84°F.

Monitored Fuel Level - Range: 0 - 100 percent: This data is the cluster's measurement of the fuel tank level as provided by the VCM/PCM on 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: This data is the fuel level the IPC is attempting to display on the fuel gage. The data may differ 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 Mile Range: 0 Miles - 999,999 Miles/Kilometers: This data refers to the displayed odometer mileage on the odometer display.

Displayed Trip Odometer - Range: 0 Miles - 9,999.9 Miles/Kilometers: 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 input refers to the PRNDL position data that is communicated to the cluster over the class 2 serial data line by the PCM/VCM. The value of this parameter corresponds to the gear that is selected on the PRNDL display. The value of this parameter will be INVALID under the following conditions:

•	The data from the PCM/VCM is INVALID.

•	The data from the PCM/VCM is PARK but the cluster does not see ground on the park switch input (pin A12).

•	A class 2 communication failure has occurred.

When the value of this parameter is INVALID, no gear will be shown as selected on the PRNDL display.

Dimming - Range: Active / Inactive: This data refers to the dimming availability feature of the PRNDL and odometer/trip odometer vacuum florescent displays. ACTIVE is displayed when the PRNDL and odometer/trip odometer vacuum florescent displays can be dimmed using the dimming thumbwheel switch. INACTIVE is displayed when the PRNDL and the odometer/trip odometer vacuum florescent displays cannot be dimmed using the dimming thumbwheel displays.

Park Switch - Range: Open / Closed: This data input refers to the state of the gear shift park position switch. OPEN is displayed when the gear shift is not fully seated in park. CLOSED is displayed when the gear shift is in the park position and the gearshift lever is at the normal rest position.

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

Low Fuel Lamp - Range: ON / OFF: This output refers to the commanded state of the LOW FUEL message located in the message center. ON is displayed when the IPC module is commanding the LOW FUEL message on. OFF is displayed when the IPC module is not commanding the LOW FUEL message on. The IPC will command the LOW FUEL message on under the following conditions:

•	When the IPC receives a class 2 (percent monitored fuel level) message of less than 18 percent from the VCM/PCM. Once the lamp is on, the Monitored Fuel Level must rise above 22 percent in order to turn the lamp off.

•	A class 2 communication failure has occurred.

Oil Pressure Lamp - Range: ON / OFF: This output refers to the commanded state of the CHECK ENG OIL PRESSURE message located in the message center. The CHECK ENG OIL PRESSURE message input to the IPC will be a discrete wire from the oil pressure sensor. The oil pressure sensor output signal must be a variable resistance to ground, as measured at the IPC connector The conditions for asserting the CHECK ENG OIL PRESSURE message in the message center display are as follows. The CHECK ENG OIL PRESSURE message will be displayed when the input resistance is less than 5 ohms and the engine is running for more than 5 seconds. The CHECK ENG OIL PRESSURE message will be removed from the message center display if the input resistance increases to 12 ohms, or the engine is not running.

Service 4WD - Range: ON / OFF: This output refers to the commanded state of the SERVICE 4WD message located in the message center. ON is displayed when the IPC module is commanding the SERVICE 4WD message ON. OFF is displayed when the IPC module is not commanding the SERVICE 4WD message on. The IPC will add the SERVICE 4WD message to the message center when the IPC receives a class 2 message from the automatic transfer case (ATC) module indicating a 4WD malfunction.

Check Coolant Temp Lamp - Range: ON / OFF: This output refers to the commanded state of the Check Coolant Temp message located in the message center. The message will be added to the message center display based on the engine coolant temperature that is sent to the IPC as a class 2 message from the VCM/PCM. If the engine temperature is greater than 250°F (121°C) the message will be added to the message center, unless the engine overheated message has been added to the message center, and removed when the engine temperature is less than 245°F (118°C).

Anti-Lock Brake System (ABS) Lamp - Range: ON / OFF: This output refers to the commanded state of the ABS lamp illumination by the IPC module. ON is displayed when the IPC module is commanding the ABS lamp to be illuminated. OFF is displayed when the IPC module is not commanding the ABS lamp to be illuminated. The IPC will command the ABS lamp to be illuminated under the following conditions:

•	When the IPC 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 RUN.

•	A class 2 communication failure occurs.

Brake Lamp - Range: ON / OFF: This output refers to the commanded state of the BRAKE lamp illumination by the IPC module. ON is displayed when the IPC module is commanding the BRAKE lamp to be illuminated. OFF is displayed when the IPC module is not commanding the BRAKE lamp to be illuminated. The IPC will command the BRAKE lamp to be illuminated under the following conditions:

•	The BRAKE lamp will flash when the IPC receives a class 2 message from the body control module (BCM) that the parking brake is set.

•	When the IPC receives a class 2 message from the electronic brake control module (EBCM) that there is a problem with the base brake system (non-ABS portion).

•	During the bulb check period for 3 seconds after the ignition switch is first turned to the RUN position.

Fasten Seat Belts - Range: ON / OFF: This output refers to the commanded state of the fasten seat belts lamp illumination by the IPC module. ON is displayed when the IPC module is commanding the fasten seat belts lamp to be illuminated. OFF is displayed when the IPC module is not commanding the fasten seat belts lamp to be illuminated. The IPC will command the fasten seat belts lamp to be illuminated under the following conditions:

•	The fasten seat belt lamp will illuminate for 20 seconds followed by 55 seconds of flashing when it receives a class 2 message from the body control module (BCM) that 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 lamp will illuminate for 20 seconds followed by 55 seconds of flashing.

Security Lamp - Range: ON / OFF: This output refers to the commanded state of the SECURITY message located in the message center. ON is displayed when the IPC module is commanding the SECURITY message on. OFF is displayed when the IPC module is not commanding the SECURITY message on. The IPC will command the SECURITY message to be displayed in the message center under the following conditions:

•	When the IPC module 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 - Range: ON / OFF (Manual Transmission Vehicle Only): This output refers to the commanded state of the SHIFT lamp illumination by the IPC module. ON is displayed when the IPC module is commanding the SHIFT lamp to be illuminated. OFF is displayed when the IPC module is not commanding the SHIFT lamp to be illuminated. The IPC will illuminate the upshift lamp when it the IPC 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 illumination by the IPC module. ON is displayed when the IPC module is commanding the high beam lamp to be illuminated. OFF is displayed when the IPC module is not commanding the high beam lamp to be illuminated. The IPC will illuminate the high beam lamp when the IPC 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) message located in the message center controlled by the IPC module. ON is displayed when the IPC module is commanding the battery message on. OFF is displayed when the IPC module is not commanding the battery message on. The IPC will command the battery message on under the following conditions:

•	The IPC receives a class 2 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.

Low Washer Fluid - Range: ON / OFF: This output refers to the commanded state of the Low Washer Fluid message located in the message center. The Low Washer Fluid message uses a discrete wire from the washer fluid bottle. ON is displayed when the IPC module is commanding the Low Washer Fluid massage on. OFF is displayed when the IPC module is not commanding the Low Washer Fluid message on. The IPC will command the Low Washer Fluid message on for 15 seconds each ignition cycle when the washer fluid switch is closed for more than 30 seconds continuously.

Cargo Lamp On - Range: ON / OFF: This output refers to the commanded state of the Cargo Lamp On message located in the message center. ON is displayed when the IPC module is commanding the Cargo Lamp On message on. OFF is displayed when the IPC module is not commanding the Cargo Lamp On message on. The message will be displayed when the cargo lamp switch is pressed and the body control module (BCM) sends a class 2 serial data message to the IPC.

Low Coolant - Range: ON / OFF: This output refers to the commanded state of the Low Coolant message located in the message center. ON is displayed when the IPC module is commanding the Low Coolant message on. OFF is displayed when the IPC module is not commanding the Low Coolant message on. The IPC will display the Low Coolant message when the IPC receives a class 2 serial data message from the PCM/VCM.

Check Eng Oil Level - Range: ON / OFF: This output refers to the commanded state of the Check Eng Oil Level message located in the message center. ON is displayed when the IPC module is commanding the Check Eng Oil Level message on. OFF is displayed when the IPC module is not commanding the Check Eng Oil Level message on. The IPC will display the Check Eng Oil Level message when the IPC receives a class 2 serial data message from the PCM/VCM.

Change Engine Oil - Range: ON / OFF: This output refers to the commanded state of the Change Engine Oil message located in the message center. ON is displayed when the IPC module is commanding the Change Engine Oil message on. OFF is displayed when the IPC module is not commanding the Change Engine Oil message on. The IPC will display the Change Engine Oil message once every ignition cycle for 15 seconds when the IPC receives a class 2 serial data message from the PCM/VCM. After the engine oil has been changed, reset the change engine oil monitor by fully pressing and releasing the accelerator pedal three times within 5 seconds after the engine oil has been changed. The Change Engine Oil message will flash for 5 seconds to notify the driver the system has been reset.

4WD Lamp - Range: ON / OFF: This output refers to the commanded state of the 4WD lamp illumination by the IPC module. ON is displayed when the IPC module is commanding the 4WD lamp to be illuminated. OFF is displayed when the IPC module is not commanding the 4WD lamp to be illuminated. The IPC will illuminate the 4WD lamp when it receives a class 2 serial data message from the PCM/VCM.

CRUISE Lamp - Range: ON / OFF: This output refers to the commanded state of the CRUISE lamp illumination by the IPC module. ON is displayed when the IPC module is commanding the CRUISE lamp to be illuminated. OFF is displayed when the IPC module is not commanding the CRUISE lamp to be illuminated. The IPC will illuminate the CRUISE lamp when it receives a class 2 serial data message from the PCM/VCM.

Engine Over-Heated - Range: ON / OFF: This output refers to the commanded state of the Engine Over-Heated message located in the message center. The message will be added to the message center display based on the engine coolant temperature that is sent to the IPC as a class 2 message from the VCM/PCM. If the engine temperature is greater than 262°F (128°C) the message will be added to the message center and removed when the engine temperature is less than 257°F (125°C).

Trans Fluid Hot - Range: ON / OFF: This output refers to the commanded state of the Trans Fluid Hot message located in the message center. The message will be added to the message center display based on the trans fluid temperature that is sent to the IPC as a class 2 message from the VCM/PCM. If the trans fluid temperature is greater than 266°F (130°C) the message will be added to the message center, unless the Trans Hot...Idle Eng message has been added to the message center, and removed when the engine temperature is less than 260°F (127°C).

Trans Hot... Idle Eng - Range: ON / OFF: This output refers to the commanded state of the Trans Hot ...Idle Eng message located in the message center. The message will be added to the message center display based on the trans fluid temperature that is sent to the IPC as a class 2 message from the VCM/PCM. If the trans fluid temperature is greater than 275°F (135°C) the message will be added to the message center and removed when the engine temperature is less than 270°F (132°C).

TOW/HAUL Lamp - Range: ON / OFF: This output refers to the commanded state of the TOW/HAUL message located in the message center. ON is displayed when the IPC module is commanding the TOW/HAUL message on. OFF is displayed when the IPC module is not commanding the TOW/HAUL On message on. The message will be displayed when the TOW/HAUL switch is pressed and the body control module (BCM) sends a class 2 serial data message to the IPC.

Air Bag Lamp - Range: ON / OFF: This output refers to the commanded state of the Air Bag lamp illumination by the Inflatable Restraint Sensing & Diagnostic Module (SDM). The Air Bag lamp is controlled by a discrete wire from the SDM. ON is displayed when the SDM grounds CKT 358. OFF in displayed when the SDM does not ground CKT 358.

Reduced Engine Power - Range: ON / OFF: This output refers to the commanded state of the Reduced Engine Power message located in the message center. ON is displayed when the IPC module is commanding the Reduced Engine Power message on. OFF is displayed when the IPC module is not commanding the Reduced Engine Power message on. The IPC will display the Reduced Engine Power message when the IPC receives a class 2 serial data message from the PCM/VCM.

Service Engine Soon Lamp - Range: ON / OFF: This output refers to the commanded state of the Service Engine Soon lamp illumination by the Powertrain Control Module (PCM). The Service Engine Soon lamp is controlled by a discrete wire from the PCM. ON is displayed when the PCM grounds CKT 419. OFF is displayed when the PCM does not ground CKT 419.