Gauge Pack - Operation

OPERATION

GAUGES

All gauges receive battery current through the CCN circuitry only when the ignition switch is in the ON or START positions. With the ignition switch in the OFF position battery current is not supplied to any gauges, and the CCN circuitry is programmed to move all of the gauge needles back to the low end of their respective scales. Therefore, the gauges do not accurately indicate any vehicle condition unless the ignition switch is in the ON or START positions.

All of the CCN gauges are driven by stepper motors. Multiple toothed electromagnets around a central gear-shaped piece of iron are located within each gauge. The electromagnets are energized by the CCN circuitry in response to messages received over the CAN data bus. To make the motor shaft turn, one electromagnet is given power, which makes the gears teeth magnetically attract to the electromagnets. As the second electromagnet is turned on the first is turned off and the gear rotates to align to the energized magnet, and the process is repeated. Each of those slight rotations is called at "step", this allows the motor to be turned to precise angles. The gauge needle moves as the magnets align to the changing magnetic fields created around it by the electromagnets.

The gauges are diagnosed using the CCN self-diagnostic test Component Tests and General Diagnostics. Proper testing of the CAN data bus and the electronic data bus message inputs to the CCN that control each gauge require the use of a diagnostic scan tool. Refer to the appropriate diagnostic information. Specific operation details for each gauge may be found elsewhere in this service information.

ENGINE TEMPERATURE GAUGE

The engine coolant temperature gauge gives an indication to the vehicle operator of the engine coolant temperature. This gauge is controlled by the Cab Compartment Node (CCN) based upon cluster programming and electronic messages received over the Controller Area Network (CAN) data bus. These electronic messages are received from the Powertrain Control Module (PCM) or Engine Control Module (ECM), depending on engine application.

The engine coolant temperature gauge is a stepper motor design unit that receives battery current on the CCN 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 CCN electronic circuitry controls the gauge needle position and provides the following features:

- Engine Temperature Low Message - Each time the CCN receives an electronic engine temperature message from the PCM or ECM indicating the temperature is below the low end of normal [about 54 °C (130 °F), the gauge needle is held at the graduation on the far left end of the gauge scale. The gauge needle remains at the low end of the gauge scale until the CCN receives a message from the PCM or ECM indicating the temperature is above about 54 °C (130 °F), or until the ignition switch is turned to the OFF position, whichever occurs first.
- Engine Temperature Message - Each time the CCN receives an electronic engine temperature message from the PCM or ECM indicating the temperature is between the low end of normal [about 54 °C (130 °F) and the high end of normal [about 122 °C (252 °F), the gauge needle is moved to the actual relative temperature position on the gauge scale.
- Engine Temperature High Message - Each time the CCN receives three consecutive electronic engine temperature messages from the PCM or ECM indicating the temperature is above about 122 °C (252 °F), the gauge needle is moved to the red increment or zone at the far right end of gauge scale, the check gauges indicator is illuminated, and a single chime tone is sounded. The gauge needle remains at the high end of the gauge scale and the check gauges indicator remains illuminated until the cluster receives a message from the PCM or ECM indicating that the temperature is below about 122 °C (252 °F), 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 check gauges indicator is cycled OFF and then ON again by the appropriate messages from the PCM or ECM.
- Communication Error - If the CCN fails to receive an engine temperature message, it will hold the gauge needle at the last indication for about 10 seconds or until the ignition switch is turned to the OFF position, whichever occurs first. After 10 seconds, the CCN will move the gauge needle to the low end of the gauge scale.

The PCM or ECM continually monitors the engine coolant temperature sensor to determine the engine operating temperature. The PCM or ECM then sends the proper messages to the CCN. For further diagnosis of the engine coolant temperature gauge or the electronic circuitry that controls the gauge Component Tests and General Diagnostics. If the instrument cluster turns ON the check gauges indicator due to a high engine temperature gauge reading, it may indicate that the engine or the engine cooling system requires service.

FUEL GAUGE

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 cluster programming and a bus message received by the cluster. This bus message is based upon a hard-wired input received by the Total Integrated Power Module (TIPM) from the fuel level sending unit on the fuel pump module, located in the fuel tank.

The fuel gauge is a stepper motor design 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 CCN electronic circuitry controls the gauge needle position and provides the following features:

- Fuel Level Sending Unit Input - The TIPM provides a constant current source to the fuel level sending unit and monitors a return input on a fuel level sense circuit. The resistance through the fuel level sending unit increases as the fuel level falls and decreases as the fuel level rises causing changes in the fuel level sense input voltage. The TIPM sends the fuel level voltage to the cluster over the Controller Area Network (CAN) bus. The cluster programming applies an algorithm to calculate the proper fuel gauge needle position based upon the fuel level bus input, then moves the gauge needle to the proper relative position on the gauge scale. This algorithm is used to dampen gauge needle movement against the negative effect that fuel sloshing within the fuel tank can have on accurate inputs from the fuel tank sending unit to the cluster.
- Less Than 10 Percent Tank Full Input - Each time the fuel level sense input to the cluster indicates the fuel tank is about 10 percent full or less for 10 consecutive seconds and the vehicle speed is zero, or for 60 consecutive seconds and the vehicle speed is greater than zero, the gauge needle is moved to about the one-sixteenth graduation on the gauge scale, the low fuel indicator is illuminated, and a single chime tone is sounded. The low fuel indicator remains illuminated until the fuel level sense input is greater than about 15 percent full for 10 consecutive seconds and the vehicle speed is zero, or for 60 consecutive seconds and the vehicle speed is greater than zero, 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 low fuel indicator is cycled OFF and then ON again by the appropriate inputs from the fuel level sending unit.
- Less Than Empty Stop Input - Each time the cluster receives a fuel level sense input that indicates the fuel level in the fuel tank is less than the EMPTY gauge needle stop position, the gauge needle is moved to the low end of the gauge scale and the low fuel indicator is illuminated immediately. This input would indicate that the fuel level sense input to the cluster is a short circuit.
- More Than Full Stop Input - Each time the cluster receives a fuel level sense input that indicates the fuel level in the fuel tank is more than the FULL gauge needle stop position, the gauge needle is moved to the low end of the gauge scale and the low fuel indicator is illuminated immediately. This input would indicate that the fuel level sense input to the cluster is an open circuit.

The instrument cluster, also known as the Cab Compartment Node (CCN) continually monitors the fuel tank sending unit to determine the level of fuel in the fuel tank. The CCN then sends the proper electronic fuel level message to other electronic modules in the vehicle over the Controller Area Network (CAN) data bus. For further diagnosis of the fuel gauge or the instrument cluster circuitry that controls the gauge Component Tests and General Diagnostics.

OIL PRESSURE GAUGE

The oil pressure gauge gives an indication to the vehicle operator of the engine oil pressure. This gauge is controlled by the Cab Compartment Node (CCN) based upon cluster programming and electronic messages received over the Controller Area Network (CAN) data bus. These electronic messages are received from the Powertrain Control Module (PCM) or Engine Control Module (ECM), depending on engine application.

The oil pressure gauge is a stepper motor design unit that receives battery current on the CCN 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 CCN electronic circuitry controls the gauge needle position and provides the following features:

- Engine Oil Pressure Message - The CCN circuitry restricts the oil pressure gauge needle operation in order to provide readings that are consistent with customer expectations. Each time the cluster receives an electronic engine oil pressure message from the PCM or ECM indicating the pressure is above about 89 kPa (13 psi) the cluster holds the gauge needle at a point near the middle increment within the normal range on the gauge scale.
- Engine Oil Pressure Low Message - Each time the CCN receives three consecutive electronic engine oil pressure messages from the PCM or ECM indicating the pressure is below about 89 kPa (13 psi), the gauge needle is moved to the red graduation at the far left end of the gauge scale, the check gauges indicator is illuminated, and a single chime tone is generated. The gauge needle remains at the left end of the gauge scale and the check gauges indicator remains illuminated until the cluster receives a message from the PCM or ECM indicating that the pressure is above about 89 kPa (13 psi), or until the ignition switch is turned to the OFF position, whichever occurs first. The cluster will only turn ON the check gauges indicator in response to a low pressure message if the engine speed is greater than zero.
- Communication Error - If the CCN fails to receive an engine oil pressure message, it will hold the gauge needle at the last indication for about 10 seconds, or until the ignition switch is turned to the OFF position, whichever occurs first. After 10 seconds, the CCN will move the gauge needle to the low end of the gauge scale.

The PCM or ECM continually monitors the engine oil pressure sensor to determine the engine oil pressure. The PCM or ECM then sends the proper messages to the CCN. For further diagnosis of the oil pressure gauge or the instrument cluster circuitry that controls the gauge Component Tests and General Diagnostics. 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.

POWER GAUGE

The power gauge gives an indication to the vehicle operator of how the Hybrid Electric Vehicle (HEV) is being operated in terms of the electric or gasoline modes and the relative gasoline fuel economy. This gauge is controlled by the instrument cluster circuit board based upon cluster programming and electronic messages received by the cluster from the Hybrid Control Processor (HCP) integral to the Traction Power Inverter Module (TPIM) over the Controller Area Network (CAN) data bus.

The power gauge is a stepper motor design unit that receives battery current on the CCN 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 CCN electronic circuitry controls the gauge needle position and provides the following features:

- Charging Position Message - Each time the cluster receives electronic messages from the HCP indicating that there is electrical energy being generated by the Regenerative Brake System (RBS) and that the high voltage battery of the HEV system is being recharged it positions the gauge needle within theCharging range of the gauge scale. The gauge needle remains within the Charging range until the cluster receives a message from the HCP to reposition the gauge needle, or until the ignition switch turns to the OFF position, whichever occurs first.
- Economy Position Message - If the cluster receives electronic messages from the HCP indicating that the vehicle is being operated in the fuel-saving hybrid electrical mode it positions the gauge needle to the appropriate relative position within the Economy range of the gauge scale. The closer the needle moves to the center of the Economy range indicates that the vehicle is achieving more fuel economy through reliance on the electrical mode of operation; while, the further the needle moves to the right of center indicates that the vehicle is achieving less fuel economy through additional reliance on the gasoline mode of operation. The gauge needle remains within the Economy range until the cluster receives a message from the HCP to reposition the gauge needle, or until the ignition switch turns to the OFF position, whichever occurs first.
- Power Position Message - Each time the cluster receives electronic messages from the HCP indicating that the vehicle is achieving the least fuel economy through reliance entirely on the gasoline mode of operation it positions the gauge needle to the appropriate relative position within the Power range of the gauge scale. The further the needle moves toward the right end of the scale, the greater the power being demanded from the gasoline engine and the lower the fuel economy being achieved. The gauge needle remains within the Power range until the cluster receives a message from the HCP to reposition the gauge needle, or until the ignition switch turns to the OFF position, whichever occurs first.
- Communication Error - If the cluster fails to receive a power gauge message, it holds the gauge needle at the last indication for about three seconds, or until the ignition switch turns to the OFF position, whichever occurs first. After three seconds, the gauge needle returns to the left end of the gauge scale.

The HCP continually monitors the HEV system circuits, sensors and components as well as inputs from the Powertrain Control Module (PCM) to determine the appropriate HEV operating mode and power gauge positioning strategies. The HCP then sends the proper electronic messages to the instrument cluster, also known as the Cab Compartment Node (CCN) to control the power gauge needle position. For further diagnosis of the power gauge or the instrument cluster circuitry that controls the gauge, Component Tests and General Diagnostics.

Use a diagnostic scan tool for proper diagnosis of the HEV systems, the HCP, the PCM, the CCN, the CAN data bus or the electronic communication related to power gauge operation. Refer to the appropriate diagnostic information.

SPEEDOMETER

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) or Engine Control Module (ECM), depending on engine application, over the Controller Area Network (CAN) data bus.

The speedometer is a stepper motor design 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:

- Vehicle Speed Message - Each time the cluster receives an electronic vehicle speed message from the PCM it will calculate the correct vehicle speed reading and position the gauge needle at that relative speed position on the gauge scale. The cluster will receive a new message and reposition the gauge pointer accordingly about every 88 milliseconds. The gauge needle will continually be positioned at the relative vehicle speed position on the gauge scale until the vehicle stops moving, or until the ignition switch is turned to the OFF position, whichever occurs first.
- Communication Error - If the cluster fails to receive a speed message, it will hold the gauge needle at the last indication for about three seconds, or until the ignition switch is turned to the OFF position, whichever occurs first. After three seconds, the gauge needle will return to the left end of the gauge scale.

The PCM continually monitors the Vehicle Speed Sensor (VSS) or electronic wheel speed messages from the Controller Anti-lock Brake (CAB) to determine the vehicle road speed. The PCM then sends the proper vehicle speed messages to the instrument cluster, also known as the Cab Compartment Node (CCN). For further diagnosis of the speedometer or the instrument cluster circuitry that controls the gauge Component Tests and General Diagnostics.

TACHOMETER

The tachometer gives an indication to the vehicle operator of the engine speed. This gauge is controlled by the Cab Compartment Node (CCN) based upon cluster programming and electronic messages received over the Controller Area Network (CAN) data bus. These electronic messages are received from the Powertrain Control Module (PCM) or Engine Control Module (ECM), depending on engine application.

The tachometer is a stepper motor design 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 CCN electronic circuitry controls the gauge needle position and provides the following features:

- Engine Speed Message - Each time the CCN receives an electronic engine speed message from the PCM or ECM it will calculate the correct engine speed reading and position the gauge needle at that relative speed position on the gauge scale. The CCN will receive a new message and reposition the gauge pointer accordingly about every 88 milliseconds. The gauge needle will continually be repositioned at the relative engine speed position on the gauge scale until the engine stops running, or until the ignition switch is turned to the OFF position, whichever occurs first.
- Communication Error - If the CCN fails to receive a speed message, it will hold the gauge needle at the last indication for about three seconds, or until the ignition switch is turned to the OFF position, whichever occurs first. After three seconds, the gauge needle will return to the left end of the gauge scale.

The PCM continually monitors the crankshaft position sensor to determine the engine speed. The ECM continually monitors the engine speed sensor to determine the engine speed. The PCM or ECM, depending on engine application, then sends the proper engine speed messages to the CCN. For further diagnosis of the tachometer or the instrument cluster circuitry that controls the gauge Component Tests and General Diagnostics.

VOLTAGE GAUGE

The voltage gauge gives an indication to the vehicle operator of the electrical system voltage. This gauge is controlled by the Cab Compartment Node (CCN) based upon cluster programming and electronic messages received over the Controller Area Network (CAN) data bus. These electronic messages are received from the Powertrain Control Module (PCM) or Engine Control Module (ECM), depending on engine application.

The voltage gauge is a stepper motor design unit that receives battery current on the CCN 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 left end of the scale after the ignition switch is turned to the OFF position. The CCN electronic circuitry controls the gauge needle position and provides the following features:

- System Voltage Message - Each time the CCN receives an electronic system voltage message from the PCM or ECM indicating the voltage is between about 9.5 volts and about 15 volts, the gauge needle is moved to the relative voltage position on the gauge scale.
- System Voltage Low (Charge Fail) Message - Each time the CCN receives three consecutive electronic system voltage messages from the PCM or ECM indicating the voltage is less than about 9 volts (charge fail condition) or that the battery temperature sensor input is an open circuit, the gauge needle is moved to the graduation on the far left end of the gauge scale and the check gauges indicator is illuminated. The gauge needle remains at the far left end of the gauge scale and the check gauges indicator remains illuminated until the cluster receives a single message from the PCM or ECM indicating the voltage is greater than about 9.5 volts (but less than about 15.5 volts), or until the ignition switch is turned to the OFF position, whichever occurs first.
- System Voltage High Message - Each time the CCN receives 3 consecutive electronic system voltage messages from the PCM or ECM indicating the voltage is greater than about 15.5 volts, the gauge needle is moved to the graduation on the far right end of the gauge scale and the check gauges indicator is illuminated. The gauge needle remains at the right end of the gauge scale and the check gauges indicator remains illuminated until the cluster receives a message from the PCM or ECM indicating the voltage is less than about 15.0 volts (but greater than about 9.5 volts), or until the ignition switch is turned to the OFF position, whichever occurs first.
- Communication Error - If the CCN fails to receive a system voltage message, it will hold the gauge needle at the last indication for about three seconds, or until the ignition switch is turned to the OFF position, whichever occurs first. After three seconds, the CCN will move the gauge needle to the far left end of the gauge scale.

The PCM or ECM continually monitors the system voltage to control the generator output. The PCM then sends the proper system voltage message to the CCN. For further diagnosis of the voltage gauge or the instrument cluster circuitry that controls the gauge Component Tests and General Diagnostics. 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.