Instrument Cluster: Operation: Indicators
Indicators are located in various positions within the EMIC and are all connected to the EMIC electronic circuit board. The turn signal indicators, security indicator, washer fluid indicator, and coolant low indicator (diesel engine only) operate based upon hard wired inputs to the EMIC. The brake indicator is controlled by PCI data bus messages from the Controller Antilock Brake (CAB) as well as by hard wired park brake switch and brake fluid level switch inputs to the EMIC. The Malfunction Indicator Lamp (MIL) is normally controlled by PCI data bus messages from the Powertrain Control Module (PCM); however, if the EMIC loses PCI data bus communication, the EMIC circuitry will automatically turn the MIL on until PCI data bus communication is restored. The EMIC uses PCI data bus messages from the Body Control Module (BCM), the Electronic Vehicle Information Center (EVIC), the PCM, the Airbag Control Module (ACM), and the CAB to control all of the remaining indicators.
The various EMIC indicators are controlled by different strategies; some receive fused ignition switch output from the EMIC circuitry and have a switched ground, others are grounded through the EMIC circuitry and have a switched battery feed, while still others are completely controlled by the EMIC microprocessor based upon various hard wired and electronic message inputs. Some indicators are illuminated at a fixed intensity, while the illumination intensity of others is synchronized with that of the EMIC general illumination lamps.
In addition, certain indicators in this instrument cluster are automatically configured or self-configured. This feature allows the configurable indicators to be enabled by the EMIC circuitry for compatibility with certain optional equipment. The ABS indicator, airbag indicator, and Tire Pressure Monitor (TPM) indicator are automatically configured by PCI data bus messages received by the EMIC from the CAB, ACM or EVIC after the EMIC is installed in the vehicle. Once these configuration settings are learned by the EMIC, a diagnostic scan tool must be used to remove these settings from the EMIC non-volatile memory. The automatically configured or self-configured indicators remain latent in each EMIC at all times and will be active only when the EMIC receives the appropriate PCI message inputs for the optional system or equipment.
The hard wired indicator inputs are diagnosed using conventional diagnostic methods. However, the EMIC circuitry and PCI bus message controlled indicators are diagnosed using the EMIC self-diagnostic actuator test. (Refer to ELECTRICAL/INSTRUMENT CLUSTER - DIAGNOSIS AND TESTING) . Proper testing of the PCI data bus and the electronic message inputs to the EMIC 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.