Part 1

OPERATION

Indicators are located in various positions within the CCN and are all connected to the CCN electronic circuit board. The door ajar indicator, high beam indicator, and turn signal indicators operate based upon CAN data bus messages. The cargo lamp indicator operates based upon hardwired inputs to the CCN. The brake indicator is controlled by CAN data bus messages from the Controller Antilock Brake (CAB) as well as by hardwired park brake switch inputs to the CCN. The seatbelt indicator is controlled by the CCN programming, CAN data bus messages from the Occupant Restraint Controller (ORC), and a hardwired seat belt switch input to the CCN. The Malfunction Indicator Lamp (MIL) is normally controlled by CAN data bus messages from the PCM; however, if the CCN loses CAN data bus communication, the CCN circuitry will automatically turn the MIL ON until CAN data bus communication is restored. The CCN uses CAN data bus messages from the Totally Integrated Power Module (TIPM), the ORC, the CAB, and the Wireless Ignition Node (WIN) to control all of the remaining indicators.

The various CCN indicators are grounded through the CCN circuitry and have a switched battery feed. All indicators are completely controlled by the CCN microprocessor based upon various hard wired and electronic message inputs. The cruise, four-wheel drive, four-wheel drive auto, four-wheel drive low, overdrive OFF and tow/haul indicators and those located within the LCD unit are dimmable. All other indicators are illuminated at a fixed intensity, which is not affected by the selected illumination intensity of the CCN general illumination lamps. The illumination intensity of the dimmable indicators is synchronized with that of the CCN general illumination lamps.

In addition, certain indicators in this instrument cluster are automatically or self-configured. This feature allows the configurable indicators to be enabled by the CCN circuitry for compatibility with certain optional equipment. The CCN defaults for the ABS indicator and airbag indicator are enabled, and these configuration settings must be programmatically disabled in the CCN using a diagnostic scan tool for vehicles that do not have this equipment. The automatically or self-configured indicators remain latent in each CCN at all times and will be active only when the CCN receives the appropriate CAN bus message inputs for that optional system or equipment.

The hard wired indicator inputs may be diagnosed using conventional diagnostic tools and procedures. However, the CCN circuitry and CAN bus message controlled indicators 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 an indicator requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information. Specific details of the operation for each indicator may be found elsewhere in this service information.

ABS INDICATOR

The ABS indicator gives an indication to the vehicle operator when the ABS system, or a circuit or component of the system is ineffective. 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 Antilock Brake Module (ABM) over the Controller Area Network (CAN) data bus.

The ABS indicator Light Emitting Diode (LED) is completely controlled by the instrument cluster logic circuit, and that logic will only allow this indicator to operate when the instrument cluster receives a battery current input on the fused ignition switch output (run-start) circuit. 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. Each time the ignition switch is turned to the ON position the ABS indicator is illuminated for about four seconds as a bulb test. The instrument cluster will turn ON the ABS indicator for the following reasons:

- ABS Indicator Lamp-On Message - Each time the cluster receives an electronic ABS indicator lamp-ON message from the ABM, the ABS indicator will be illuminated. The indicator remains illuminated until the cluster receives a lamp-OFF message from the ABM, or until the ignition switch is turned to the OFF position, whichever occurs first.
- Communication Error - If the cluster receives no lamp-ON or lamp-OFF messages from the CAB for five consecutive message cycles, the ABS indicator is illuminated. The indicator remains illuminated until the cluster receives a valid message from the ABM, or until the ignition switch is turned to the OFF position, whichever occurs first.
- ABS Diagnostic Test - The ABS indicator is blinked ON and OFF by lamp-ON and lamp-OFF messages from the ABM during the performance of the ABS diagnostic tests.

The Antilock Brake Module (ABM) continually monitors the ABS circuits and sensors to decide whether the system is in good operating condition. The ABM then sends the proper lamp-ON or lamp-OFF message to the instrument cluster, also known as the Cab Compartment Node (CCN). If the ABM sends a lamp-ON message after the bulb test, it indicates that the ABM has detected a system malfunction or that the ABS system has become ineffective. The ABM will store a Diagnostic Trouble Code (DTC) for any malfunction it detects. Each time the ABS indicator fails to light due to an open or short in the cluster ABS indicator circuit, the cluster sends a message notifying the ABM of the condition, then the instrument cluster and the ABM will each store a DTC.

AIRBAG INDICATOR

The airbag indicator gives an indication to the vehicle operator when the airbag system, or a circuit or component of the system is ineffective. The airbag 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 Occupant Restraint Controller (ORC) over the Controller Area Network (CAN) data bus.

The airbag indicator Light Emitting Diode (LED) is completely controlled by the instrument cluster logic circuit, and that logic will only allow this indicator to operate when the instrument cluster receives a battery current input on the fused ignition switch output (run-start) circuit. 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. Each time the ignition switch is turned to the ON position the airbag indicator is illuminated for about six to eight seconds. The entire bulb test is a function of the ORC. The instrument cluster will turn ON the airbag indicator for the following reasons:

- Airbag Indicator Lamp-On Message - Each time the cluster receives an electronic airbag indicator lamp-ON message from the ORC, the airbag indicator will be illuminated. The indicator remains illuminated for about twelve seconds or until the cluster receives a lamp-OFF message from the ORC, whichever is longer. This indicator will also be extinguished when the ignition switch is turned to the OFF position.
- Communication Error - If the cluster receives no lamp-ON or lamp-OFF messages from the ORC for 10 consecutive message cycles, the airbag indicator is illuminated. The indicator remains illuminated until the cluster receives a single lamp-OFF message from the ORC.

The ORC continually monitors the airbag system circuits and sensors to decide whether the system is in good operating condition. The ORC then sends the proper lamp-ON or lamp-OFF message to the instrument cluster, also known as the Cab Compartment Node (CCN). If the ORC sends a lamp-ON message after the bulb test, it indicates that the ORC has detected a system malfunction or that the air bags and seat belt tensioners may not deploy when required, or may deploy when not required. The ORC will store a Diagnostic Trouble Code (DTC) for any malfunction it detects. Each time the airbag indicator fails to illuminate due to an open or short in the cluster airbag indicator circuit, the cluster sends a message notifying the ORC of the condition, the instrument cluster and the ORC will each store a DTC, and the cluster will flash the seatbelt indicator ON and OFF as a backup to notify the vehicle operator.

BRAKE INDICATOR

The brake indicator gives an indication to the vehicle operator when the parking brake is applied, when there are certain brake hydraulic system malfunctions as indicated by a low brake hydraulic fluid level condition, or when the brake fluid level switch is disconnected. The brake indicator can also give an indication when certain faults are detected in the Antilock Brake System (ABS). This indicator is controlled by a transistor on the instrument cluster circuit board based upon cluster programming, electronic messages received by the cluster from the Controller Antilock Brake (CAB) over the Controller Area Network (CAN) data bus, and a hard wired input from the park brake switch.

The brake indicator Light Emitting Diode (LED) is completely controlled by the instrument cluster logic circuit, and that logic will only allow this indicator to operate when the instrument cluster receives a battery current input on the fused ignition switch output (run-start) circuit. 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. Each time the ignition switch is turned to the ON position the brake indicator is illuminated for about four seconds as a bulb test. The instrument cluster will turn ON the brake indicator for the following reasons:

- Brake Indicator Lamp-On Message - Each time the cluster receives an electronic brake indicator lamp-ON message from the CAB, the brake indicator will be illuminated. The CAB may also send lamp-ON messages as feedback during ABS diagnostic procedures. The indicator remains illuminated until the cluster receives a lamp-OFF message from the CAB, or until the ignition switch is turned to the OFF position, whichever occurs first.
- Park Brake Switch Input - Each time the cluster detects ground on the park brake switch sense circuit (park brake switch closed = park brake applied or not fully released) while the ignition switch is in the ON position, the brake indicator flashes ON and OFF. The indicator continues to flash until the park brake switch sense input to the cluster is an open circuit (park brake switch open = park brake fully released), or until the ignition switch is turned to the OFF position, whichever occurs first.

The park brake switch on the park brake pedal mechanism provides a hard wired ground input to the instrument cluster circuitry through the park brake switch sense circuit whenever the park brake is applied or not fully released. The CAB continually monitors the ABS system circuits and sensors, including the brake fluid level switch on the brake master cylinder reservoir, to decide whether the system is in good operating condition. The CAB then sends the proper lamp-ON or lamp-OFF message to the instrument cluster, also known as the Cab Compartment Node (CCN). If the CAB sends a lamp-ON message after the bulb test, it indicates that the CAB has detected a brake hydraulic system malfunction or that the ABS system has become ineffective. The CAB will store a Diagnostic Trouble Code (DTC) for any malfunction it detects.

CARGO LAMP INDICATOR

The cargo lamp indicator gives an indication to the vehicle operator when the exterior cargo lamp is illuminated. This indicator is controlled by a transistor on the instrument cluster circuit board based upon cluster programming, a hardwired multiplex input received by the cluster from the cargo lamp switch on the headlamp dimmer switch mux circuit.

The cargo lamp indicator Light Emitting Diode (LED) is completely controlled by the instrument cluster logic circuit and is only on when the cargo lamp is on. The cargo lamp indicator also remains active when the key is out of the ignition. The LED only illuminates when it is provided a path to ground by the instrument cluster transistor. The instrument cluster will turn ON the cargo lamp indicator for the following reasons:

- Cargo Lamp-On Input - Each time the cluster detects a cargo lamp-ON input from the headlamp switch on the headlamp dimmer switch mux circuit, the cargo lamp and the cargo lamp indicator will be illuminated. The cargo lamp and indicator remain illuminated until the cluster receives a cargo lamp-OFF input from the headlamp switch, until the cluster has completed an exterior lamps load shed (about fifteen minutes).

The CCN continually monitors the headlamp dimmer switch circuit to determine the proper interior lamps features and panel lamps illumination levels to provide. The CCN then energizes and de-energizes a low side driver circuit to control the exterior cargo lamp. Each time the CCN energizes the cargo lamp driver and the ignition switch is in the ON or START positions, the CCN also turns ON the cargo lamp indicator. For further diagnosis of the cargo lamp indicator or the instrument cluster circuitry that controls the indicator Component Tests and General Diagnostics.

CHARGING INDICATOR

The charging indicator gives an indication to the vehicle operator when the electrical system voltage is too low or too high. This indicator is controlled by the 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 charging indicator Light Emitting Diode (LED) is completely controlled by the CCN logic circuit, and that logic will only allow this indicator to operate when the instrument cluster receives a battery current input on the fused ignition switch output (run-start) circuit. 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 a transistor on the CCN circuit board. Each time the ignition switch is turned to the ON position the charging indicator is illuminated by the CCN for about two seconds as a bulb test. The charging indicator will be turned ON for the following reasons:

- Voltage Low Message - Each time the CCN receives an electronic system voltage message from the PCM or ECM indicating the voltage is low (less than about 11.5 volts is a charge fail condition), the charging indicator will be illuminated. The indicator remains illuminated until the cluster receives a message from the PCM indicating the voltage is normal (greater than about 12.0 volts, but less than 16.0 volts), or until the ignition switch is turned to the OFF position, whichever occurs first.
- Voltage High Message - Each time the CCN receives an electronic system voltage message from the PCM or ECM indicating the voltage is high (greater than about 16.0 volts), the charging indicator will be illuminated. The indicator remains illuminated until the CCN receives a message from the PCM or ECM indicating the voltage is normal (less than about 15.5 volts, but greater than 11.5 volts), or until the ignition switch is turned to the OFF position, whichever occurs first.

The PCM or ECM continually monitors the electrical system voltage to control the generator output. The PCM or ECM then sends the proper messages to the CCN. If the charging indicator is turned ON due to a charge fail or voltage high condition, it may indicate that the charging system requires service. For further diagnosis of the charging indicator or the CCN circuitry that controls the indicator, Component Tests and General Diagnostics.

CRUISE INDICATOR

The cruise indicator gives an indication to the vehicle operator when the electrical system voltage is too low or too high. This indicator is controlled by the CCN based upon cluster programming and electronic messages received over the Controller Area Network (CAN) data bus. These electronic messages are received from the PCM or ECM, depending on engine application.

The cruise indicator Light Emitting Diode (LED) is completely controlled by the CCN logic circuit, and that logic will only allow this indicator to operate when the instrument cluster receives a battery current input on the fused ignition switch output (run-start) circuit. 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 a transistor on the CCN circuit board. The cruise indicator will be turned ON for the following reasons:

- Cruise Indicator Lamp-On Message - Each time the CCN receives an electronic cruise indicator lamp-ON message from the PCM or ECM indicating the speed control system is ON, the cruise indicator is illuminated. The indicator remains illuminated until the cluster receives a lamp-OFF message from the PCM or ECM or until the ignition switch is turned to the OFF position, whichever occurs first.

The PCM or ECM continually monitors the speed control switches to determine the proper outputs to the speed control servo. The PCM or ECM then sends the proper lamp-ON or lamp-OFF message to the CCN. For further diagnosis of the cruise indicator or the instrument cluster circuitry that controls the LED Component Tests and General Diagnostics.

DIESEL EXHAUST BRAKE INDICATOR

The Variable Geometry Turbocharger (VGT) works in conjunction with the engine and the transmission to provide an integrated braking system used to help slow the vehicle. This is commonly called exhaust braking. The diesel exhaust brake indicator gives an indication to the vehicle operator when the exhaust brake feature is active. This indicator is controlled by the CCN based upon cluster programming and electronic messages received from the PCM over the Controller Area Network (CAN) data bus. The exhaust brake feature will only function when the driver turns the exhaust brake switch to the ON position.

Once the switch is in the ON position and the vehicle is moving faster than 8 k/h (5 MPH); the exhaust brake will automatically operate when the driver removes pressure from the throttle pedal allowing the engine to see 0% throttle and 0 fuel delivery. Exhaust braking is most effective when the engine RPM is higher. The automatic transmission has been programmed to downshift more aggressively when the exhaust brake is enabled to increase exhaust brake assistance. Use of automatic transmission Tow/Haul Mode improves interaction between the engine and transmission. Inputs to the exhaust brake feature include:

- Coolant temperature
- Ambient air temperature
- Exhaust manifold pressure sensor
- Throttle pedal position sensor
The PCM continually monitors these sensors, and fault codes with any of these sensors will cause the exhaust brake feature to be disabled.

DIESEL EXHAUST FLUID (DEF) INDICATOR

The diesel exhaust fluid indicator gives an indication to the vehicle operator when the DEF fluid is low or a system malfunction is present. This indicator is controlled by the CCN based upon cluster programming and electronic messages received from the PCM over the Controller Area Network (CAN) data bus.

The diesel exhaust fluid indicator Light Emitting Diode (LED) is completely controlled by the CCN logic circuit, and that logic will only allow this indicator to operate when the instrument cluster receives a battery current input on the fused ignition switch output (run-start) circuit. 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 CCN. Each time the ignition switch is turned to the ON position the water-in-fuel indicator is illuminated for about two seconds as a bulb test. The water-in-fuel indicator will be turned ON for the following reasons:

- Diesel Exhaust fluid Indicator Lamp-On Message - Each time the CCN receives an electronic lamp-ON message from the PCM indicating that the DEF fluid is low, the DEF indicator will be illuminated. The indicator remains illuminated until the cluster receives a lamp-OFF message from the PCM, or until the ignition switch is turned to the OFF position, whichever occurs first.

The PCM continually monitors the DEF fluid level sensor to determine whether there is sufficient fluid in the tank. The PCM then sends the proper lamp-ON or lamp-OFF message to the CCN. For further diagnosis of the DEF indicator or the instrument cluster circuitry that controls the indicator Component Tests and General Diagnostics.