Principles of Operation

Instrumentation, Message Center and Warning Chimes


Principles of Operation

When installing a new Instrument Cluster (IC), it is necessary to upload the module configuration information to the scan tool. Following installation of the IC, download the module configuration information from the scan tool into the new IC. For additional module configuration information, refer to Information Bus.

The IC is a configurable, hybrid electronic cluster that contains a microprocessor, gauges, indicator lamps, message center, warning chimes and internal circuitry. The IC uses hardwired circuitry, the Standard Corporate Protocol (SCP), and the Controller Area Network (CAN) to transmit and receive data from other modules.

It is very important to understand:

- where the input originates.
- all the information necessary in order for a feature to operate.
- which module(s) receive(s) the input or command message.
- whether the module which received the input controls the output of the feature, or whether it outputs a message over the CAN or SCP communication networks circuits to another module.
- which module controls the output of the feature.


Instrument Cluster (IC)

IC Messages

The IC uses input messages from other modules to control the gauges, informational indicators, warning indicators and reconfigurable telltale indicators over the communication networks. If a required message is missing or invalid for less than 5 seconds, the gauge or indicator that requires the message remains at the last commanded state based upon the last known good message. For example, if the brake status message is missing for less than 5 seconds and the brake warning indicator was ON, the indicator remains in the ON state until the next good message is received. If the message remains missing or invalid for greater than 5 seconds, the IC sets a U-code DTC and the output becomes a default action for the indicator or gauge. Each indicator or gauge utilizes a different default strategy depending on the nature of the indication. If the messaged input to the cluster returns at any time, the normal function of the gauge or indicator resumes.

NOTE: Whenever a message is suspected as missing and confirmed by a missing message DTC (U-code), it is important to look for other symptoms that may also be present in the IC and throughout the vehicle. Once a DTC is set in the IC, it may be helpful to review the complete message list available in Information Bus to see what other modules also rely on the same message and run the self-test for those modules. If the message is missing from other modules, the same DTC may also be set in those modules. Confirmation of missing messages common to multiple modules may indicate that the originating module is the source of the concern or the communication network may be experiencing some concerns.

IC Prove-Out

The IC and other vehicle modules carry out a display prove-out to verify that all module controlled warning/indicator lamps and monitored systems are functioning correctly within the IC. When the ignition switch is cycled to the ON position with the engine off, the indicators illuminate to prove-out according the following table:






Information And Message Center

The message center is an integral part of the IC that receives and acts upon much of the same information that is input and used to operate the IC gauges, indicators, warning indicators and reconfigurable telltale indicators. The message center, located in the center of the IC is a Vacuum Fluorescent (VF) 2-line display. The message center electronic functions use both hardwired, and the CAN circuitry to transmit and receive information.


Warning Chimes

The IC uses different chimes to alert the driver of various vehicle conditions as follows:

- Safety belt warning (repetitive chime)
- Belt-Minder(R) warning (repetitive chime after a delay and after the safety belt chime is completed)
- Key-in-ignition warning (repetitive chime)
- Headlamps on warning (repetitive chime)
- Door ajar warning (single tone chime)
- Air bag warning (repetitive chime)
- Message center warning (single tone)

Safety Belt Warning Chime

The safety belt warning chime warns that the safety belt is not fastened. The safety belt warning chime sounds when the driver safety belt is not fastened and the ignition key is turned from the OFF/LOCK or ACC to the ON or START position.

The safety belt warning chime stops sounding when the safety belt is fastened, the ignition key is turned from the ON or START position to the OFF/LOCK or ACC position, or the chime sounds for approximately 6 seconds.

The safety belt warning chime inputs are the:

- Ignition switch position
- Driver safety belt switch status signal from the Restraints Control Module (RCM)

Belt-Minder(R)

The Belt-Minder(R) is configurable. To configure using a scan tool, refer to Information Bus. To configure without using a scan tool, refer to Belt-Minder(R) Deactivating/Activating Service and Repair.

NOTE: The Belt-Minder(R) is disabled for one ignition switch ON cycle if the safety belt is buckled then unbuckled during that specific ignition switch cycle.

The Belt-Minder(R) feature supplements the current safety belt warning function. The Belt-Minder(R) is enabled after the current safety belt warning is complete. The Belt-Minder(R) reminds the driver that the driver or passenger front safety belt is unbuckled by intermittently sounding a chime and illuminating the safety belt warning lamp in the IC once the vehicle speed exceeds 5 km/h (3 mph). While activated, the Belt-Minder(R) alternates the chime and indicator from on for 6 seconds to off for 30 seconds.

Key-In-Ignition Warning Chime

The key-in-ignition warning chime warns that the key is still in the ignition lock cylinder when the driver door is ajar. The chime sounds when the driver door is ajar, the key is in the ignition lock cylinder and in the OFF/LOCK or ACC position.

The chime stops sounding when the driver door is closed, the key is removed from the ignition lock cylinder, or if the ignition lock cylinder is turned to the ON position.

The key-in-ignition warning chime inputs are the:

- Ignition switch ON position
- Door ajar signal from the driver door ajar switch
- Key-in-ignition switch signal from the ignition switch

Headlamps On Warning Chime

The headlamps on warning chime warns that the headlamps are on when the driver door is ajar and the key is removed from the ignition lock cylinder. The headlamps on warning chime sounds if the driver door is ajar, the headlamp switch is in the HEADLAMPS or PARKING LAMPS ON position, and the ignition key is in the OFF/LOCK position.

The chime stops sounding when any one of the above conditions are removed.

The headlamps on warning chime inputs are the:

- Ignition switch position
- Door ajar signal from the driver door ajar switch
- Parking lamps on/off signal from the headlamp switch

Turn Signal On Warning Chime

The turn signal on warning chime warns that the turn signal has not been cancelled. The turn signal on warning chime sounds if the left or right turn signal is on and the vehicle has traveled more than 3.2 km (2.0 miles).

The turn signal on warning chime stops sounding if the turn signal is turned off, or if the ignition lock cylinder is turned to the OFF or ACC position.

The turn signal on warning chime inputs are:

- Turn signal on signal from the multifunction switch
- Odometer count data communicated by the IC through the Medium Speed Controller Area Network (MS-CAN) communication bus

Door Ajar Warning Chime

The door ajar warning chime warns that a door is not fully closed. The chime sounds when any door, or the luggage compartment lid becomes ajar while the ignition key is in the ON position.

The door ajar warning lamp/chime inputs are the:

- Ignition switch position
- Door ajar signal from the door ajar or luggage compartment lid ajar switches

Air Bag Warning Chime

The air bag warning chime warns that a fault is present in the Supplemental Restraint System (SRS). When a fault is present in the SRS, the Lighting Control Module (LCM) receives a request from the Restraints Control Module (RCM) and sounds the air bag warning chime. If a fault is present in the SRS when the ignition switch is placed in the ON position, the air bag warning chime sounds only 90 seconds after the key cycle.

The air bag warning chime inputs are the:

- Ignition switch position
- Air bag warning chime request signal from the RCM

Message Center Warning Chime

The message center warning chime sounds when a warning message is displayed on the message center. If multiple warning messages are present, a chime tone sounds for each of the warnings that are displayed.

The message center warning chime inputs are the warning messages displayed on the message center.