Part 1

OPERATION

Indicators are located in various positions within the Electromechanical Instrument Cluster (EMIC), and are all connected to the EMIC electronic circuit board. Some indicators operate based upon hard-wired inputs to the EMIC, but most are controlled by Controller Area Network (CAN) or Local Interface Network (LIN) data bus messages from other electronic modules in the vehicle. Some are controlled by a combination of hard-wired inputs, electronic messaging and EMIC programming. If the EMIC loses CAN data bus communication, the EMIC circuitry will automatically turn ON the Malfunction Indicator Lamp (MIL) until CAN data bus communication is restored. If the EMIC looses CAN data bus communication with the Totally Integrated Power Module (TIPM), all of the modules that are supported by the CAN C data bus will illuminate the appropriate cluster tell tail warnings.

The various EMIC indicators are controlled by different strategies; some receive fused ignition switch output from the EMIC circuitry and have a switched ground, while others are grounded through the EMIC circuitry and have a switched battery feed. However, all indicators are completely controlled by the EMIC microprocessor based upon various hard-wired and electronic message inputs. The cruise indicator located within the odometer Vacuum-Florescent Display (VFD) unit is dimmable. All other indicators are illuminated at a fixed intensity, which is not affected by the selected illumination intensity of the EMIC general illumination lighting. The illumination intensity of the dimmable indicator is synchronized with that of the general illumination lighting.

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

Hard-wired circuitry connects the EMIC to the electrical system of the vehicle. These hard-wired circuits are integral to several wire harnesses, which are routed throughout the vehicle and retained by many different methods. These circuits may be connected to each other, to the vehicle electrical system and to the EMIC through the use of a combination of soldered splices, splice block connectors, and many different types of wire harness terminal connectors and insulators. Refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, further details on wire harness routing and retention, as well as pin-out and location views for the various wire harness connectors, splices and grounds.

The hard-wired indicator inputs may be diagnosed using conventional diagnostic tools and procedures. However, the EMIC circuitry and electronic CAN or LIN data bus message controlled indicators are diagnosed using the instrument cluster self-test Testing and Inspection. Proper testing of the CAN or LIN data bus and the electronic data bus message inputs to the EMIC that control each indicator requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic 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 Controller Antilock Brake (CAB) over the 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 three seconds as a bulb test. The entire bulb test is a function of the CAB. 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 CAB, the ABS indicator will be illuminated. 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.
- 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 CAB, 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 CAB during the performance of the ABS diagnostic tests.

The CAB continually monitors the ABS circuits and sensors to decide whether the system is in good operating condition. The CAB then sends the proper lamp-ON or lamp-OFF message to the EMIC. If the CAB sends a lamp-ON message after the bulb test, it indicates that the CAB has detected a system malfunction or that the ABS system has become ineffective. The CAB 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 CAB of the condition, then the instrument cluster and the CAB will each store a DTC and the cluster will flash the brake indicator ON and OFF as a backup to notify the vehicle operator.

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 CAN data bus.

The airbag indicator 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 12 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 EMIC. 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 airbags and seat belt tensioners may not deploy when required, or may deploy when not required. The ORC will store a 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, then the instrument cluster and the ORC will each store a DTC.

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 CAN data bus, and a hard-wired input from the park brake switch.

The brake indicator 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 by the instrument cluster for about three 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, and the gear position changes from the park 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. If the park brake is not fully released , and the vehicle is moving at 8 mph, the chime will sound.
- Antilock Brake System (ABS) Indicator Backup - If the instrument cluster detects a fault in the ABS indicator circuit it will send a message indicating the fault to the CAB, then flash the brake indicator ON and OFF. The cluster will continue to flash the brake indicator until the ABS indicator circuit fault is resolved, or until the ignition switch is turned to the OFF position, whichever occurs first.

The park brake switch on the park brake lever 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 TIPM monitors the brake fluid level switch on the brake master cylinder reservoir, then sends the appropriate electronic messages to the CAB. The CAB continually monitors the ABS system circuits and sensors to decide whether the system is in good operating condition. The CAB then sends the proper lamp-ON or lamp-OFF message to the EMIC. 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 DTC for any malfunction it detects.

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 a transistor on the instrument cluster circuit board based upon cluster programming and electronic messages received by the cluster from the PCM/ECM, over the CAN data bus.

The charging indicator 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 charging indicator is illuminated by the instrument cluster for about three seconds as a bulb test. The instrument cluster will turn ON the charging indicator for the following reasons:

- Voltage Low Message - Each time the cluster receives an electronic system voltage message from the PCM/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/ECM 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 cluster receives an electronic system voltage message from the PCM/ECM indicating the voltage is high (greater than about 16.0 volts), the charging indicator will be illuminated. The indicator remains illuminated until the cluster receives a message from the PCM/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/ECM continually monitors the electrical system voltage to control the generator output. The PCM/ECM then sends the proper messages to the EMIC. If the instrument cluster turns ON the charging indicator due to a charge fail or voltage high condition, it may indicate that the charging system requires service.

LOW COOLANT INDICATOR

The low coolant indicator gives an indication to the vehicle operator that the level of coolant contained in the engine coolant reservoir is below the minimum recommended level. This indicator is controlled by the instrument cluster logic circuit based upon cluster programming and electronic messages received over the CAN data bus from the PCM/ECM.

The low coolant indicator function of the odometer VFD unit 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 odometer VFD low coolant indication will always be OFF when the ignition switch is in any position except ON or START. The instrument cluster will turn ON the low coolant indicator for the following reasons:

- Low Coolant Indicator Lamp-On Message - Each time the cluster receives an electronic low coolant indicator lamp-ON message from the PCM/ECM indicating that the engine coolant level is low, the low coolant indicator will be illuminated. The indicator remains illuminated until the cluster receives a lamp-OFF message from the PCM/ECM, or until the ignition switch is turned to the OFF position, whichever occurs first.

The PCM/ECM continually monitors an input from the coolant level sensor to determine the level of coolant in the engine coolant reservoir. The PCM/ECM then sends the proper lamp-ON or lamp-OFF message back to the EMIC.

CRUISE INDICATOR

The cruise indicator gives an indication to the vehicle operator when the speed control system is ON, regardless of whether the speed control is engaged. This indicator is controlled by the instrument cluster circuit board based upon cluster programming and electronic messages received by the cluster from the PCM/ECM over the CAN data bus.

The cruise indicator 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 indicator will always be OFF when the ignition switch is in any position except ON or START. The indicator only illuminates when it is energized by the instrument cluster logic circuit. The instrument cluster will turn ON the cruise indicator for the following reasons:

- Cruise Indicator Lamp-On Message - Each time the cluster receives an electronic cruise indicator lamp-ON message from the PCM/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/ECM, or until the ignition switch is turned to the OFF position, whichever occurs first.

The PCM/ECM continually monitors the speed control switches to determine the appropriate outputs to the speed control servo. The PCM/ECM then sends the proper lamp-ON or lamp-OFF message to the EMIC.

DOOR AJAR INDICATOR

The ajar indicators give an indication to the vehicle operator that one or more of the passenger compartment doors or the liftgate may be open or not completely latched. These indicators are controlled by the instrument cluster logic circuit based upon cluster programming and electronic ajar switch status messages received by the cluster from the TIPM over the CAN data bus.

The ajar indicator function of the odometer or Electronic Vehicle Information Center (EVIC) VFD unit 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 B(+) circuit. Therefore, the VFD ajar indications can occur regardless of the ignition switch position. The instrument cluster will turn ON the ajar indicator for the following reasons:

- Ajar Switch Message Input - Each time the EMIC receives an electronic door or liftgate ajar switch status message indicating that a door, the liftgate or any combination of these is open or not completely latched with the ignition switch in any position, the appropriate ajar indication will be illuminated. If the cluster detects a vehicle speed input greater than zero (kilometers or miles-per-hour) while the ignition switch is in the ON or START positions, the ajar indication will be accompanied by a single chime tone. When the ignition switch is in any position except ON or START, any and all ajar indications will time out after about five minutes.

The TIPM continually monitors the door and liftgate ajar switches to determine the status of the doors and liftgate. The TIPM then sends the proper ajar switch status messages to the EMIC.