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Home >> Dodge or Ram Truck >> 2012 >> Grand Caravan V6-3.6L >> Repair and Diagnosis >> Instrument Panel, Gauges and Warning Indicators >> Instrument Cluster / Carrier >> Description and Operation >> Instrument Cluster Indicators - Operation >> Part 2

Part 2





OPERATION - LHD

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 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 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 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 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 CCN. 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 CCN.
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