Indicators, Instrument Cluster: Operation

Indicators are located in various positions within the Instrument Panel Cluster (IPC) and are all connected to the printed circuit board of the IPC. Some indicators operate based upon hard-wired inputs to the IPC, but most are controlled by Controller Area Network (CAN) data bus messages from other electronic modules in the vehicle. If the IPC loses CAN data bus communication, the IPC circuitry will automatically turn on the Malfunction Indicator Lamp (MIL) until CAN data bus communication is restored.

The various IPC indicators are controlled by different strategies; some require fused ignition output to the IPC circuitry and have a switched ground, while others are grounded through the IPC circuitry and have a switched battery feed. However, all indicators are completely controlled by the IPC microcontroller based upon various hardwired and electronic message inputs. A few, non-critical indicators are dimmable, but most indicators are illuminated at a fixed intensity, which is not affected by the selected illumination intensity of the IPC general illumination Light Emitting Diode (LED) units. The illumination intensity of the dimmable indicators is synchronized with that of the general illumination lighting.

In addition, certain indicators in this IPC are automatically or self-configured. This feature allows the configurable indicators to be enabled by the IPC circuitry for compatibility with certain optional equipment. These indicators are enabled or disabled by an electronic configuration message sent to the IPC by the Body Control Module (BCM). The defaults for some indicators may be enabled and these configuration settings must be programmatically disabled in the BCM using a diagnostic scan tool for vehicles that do not have the equipment the indicator supports. The automatically or self-configured indicators remain latent in each IPC at all times and will be active only when the IPC receives the appropriate CAN bus message inputs for that optional system or equipment.

The hardwired indicator inputs may be diagnosed using conventional diagnostic tools and procedures. However, the IPC circuitry and electronic CAN data bus message controlled indicators are diagnosed using the self-diagnostic test. Proper testing of the CAN data bus and the electronic data bus message inputs to the IPC that control each indicator requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.