Principles of Operation
Instrumentation, Message Center and Warning Chimes
Principles of Operation
NOTE: The Smart Junction Box (SJB) is also known as the Generic Electronic Module (GEM).
NOTE: When installing a new Instrument Panel Cluster (IPC), it is necessary to upload the module configuration to the scan tool. Following installation of the IPC, download the module configuration from the scan tool into the new IPC. Refer to Information Bus to carry out the Programmable Module Installation (PMI). On vehicles equipped without Intelligent Access (IA), it is also necessary to carry out a parameter reset procedure whenever a new IPC or PCM is installed. Refer to Antitheft and Alarm Systems. Programmable Module Installation (PMI)
The IPC utilizes a microprocessor to control the gauge, indicator, message center and warning chime functions. Data is sent to the IPC over the Medium Speed Controller Area Network (MS-CAN) and the High Speed Controller Area Network (HS-CAN) bus lines and through hardwired circuitry from individual components. The IPC uses each input to output an action to the gauges or indicators.
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.
- does the module which received the input control the output of the feature, or does it output a message over the communication network to another module.
- which module controls the output of the feature.
Instrument Panel Cluster (IPC)
IPC Gateway Function
The IPC acts as a gateway module by receiving information in one format and transmitting it to other modules using another format. For example, the IPC receives the vehicle speed data from the PCM over the HS-CAN, converts the data into an MS-CAN message and sends (gateways) the message to other network modules such as the HVAC module, the Audio Control Module (ACM) and the SJB. This enables network communication between modules that do not communicate using the same network (HS-CAN or the MS-CAN).
IPC Network Messages
The IPC uses input messages from other modules to control the gauges, informational indicators and warning 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 IPC 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. Refer to the normal operation descriptions located before each individual pinpoint test for further description of the default action specific to each indicator or gauge. If the messaged input to the cluster returns at any time, the normal function of the gauge or indicator resumes.
NOTE: Whenever a network 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 IPC and throughout the vehicle. Once a DTC is set in the IPC, 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 problems.
IPC Configuration
The IPC contains items that are configurable. While some configurable items are customer preference items, most items are configured at the end of the line production and only available for configuration through the PMI procedure or by using As-Built data. Refer to Information Bus.
IPC Configuration Parameters
IPC Prove-Out
The IPC carries out a display prove-out to verify that all module controlled warning/indicator lamps and monitored systems are functioning correctly within the IPC. When the ignition is turned to the ON mode with the engine off, the indicators illuminate to prove-out according to the following table:
Information And Message Center
The message center is an integral part of the IPC that receives and acts upon much of the same information that is input and used to operate the IPC gauges, informational indicators, warning indicators and warning chimes. The message center is a 2-line display located in the center of the IPC. The message center electronic functions use both hardwired circuitry and the Controller Area Network (CAN) to display information.
Warning Chimes
The IPC uses inputs that are both hardwired to individual components and messages that are sent from the other modules over the HS-CAN or MS-CAN to control the warning chime functions.
Warning Chime Characteristics
The warning chimes have unique characteristics to identify and differentiate each warning chime. The warning chimes use volume, chime frequency, length of time the chime sounds and the number of chime tones to identify which chime is sounding. The IPC prioritizes the chimes according to a preset hierarchy programmed into the IPC software. When more than one chime request is received by the IPC, the most important chime sounds. If a lower priority chime is currently sounding, the higher priority request takes over and replaces the lower priority chime.
There are 3 different chimes as listed below:
- Repetitive
- Single-tone
- Tick-tock
The following table provides a summary of the chime characteristics including the chime priority.
Instrument Panel Cluster (IPC) Chime Characteristics
Active Park Assist Chime
The active park assist chime uses several different chime tones depending on the nature of the requested chime and the urgency for acknowledgement of the chime as determined by the PAM. The chime is either 1 of 3 single tone chimes with varying tone lengths or 1 of 2 repetitive chimes with varying tone lengths and number of chime tones. Refer to Collision Avoidance and Parking Assist Systems or the Owner's Literature for information on the active park assist function. The message center displays instructional or fault messages combined with the active park assist chime whenever the PAM sends the chime on command.
The active park assist chime inputs are:
- Ignition state.
- Active park assist warning command transmitted from the PAM over the HS-CAN bus.
Adaptive Cruise Control Warning Chime
The adaptive cruise control warning chime supplements the message center displays to draw the driver's attention to the need to intervene and take control of the vehicle. There are 2 levels of chime output (high priority and low priority) based upon the nature of the warning message.
The low priority adaptive cruise control warning chime is a single-tone chime that sounds to alert the driver that the adaptive cruise control system has shut itself off due to low vehicle speed (approximately 32 km/h [20 mph]) and that the driver needs to intervene if further braking is required or to resume the adaptive cruise control operation.
The high priority adaptive cruise control warning chime is also a single tone chime that is longer than the low priority chime. The chime increases in intensity and alerts the driver that the vehicle is approaching the vehicle ahead at a faster rate then the adaptive cruise control system can brake the vehicle and that the driver needs to apply the brakes to slow the vehicle down.
Both low and high priority adaptive cruise control warning chimes are accompanied by the DRIVER INTERVENE warning message.
The adaptive cruise control warning chime inputs are:
- Ignition state.
- Adaptive cruise control warning chime request communicated by the Cruise-Control Module (C-CM) to the IPC over the HS-CAN.
Air Bag Secondary Warning Chime
The air bag secondary warning chime warns that the air bag warning indicator light does not work correctly and that a Supplemental Restraint System (SRS) fault condition exists. The IPC monitors the air bag warning indicator status internally. When a fault is present in the air bag warning indicator and the IPC receives an air bag warning indicator on request from the Restraints Control Module (RCM), the air bag secondary warning chime sounds.
The air bag secondary warning chime inputs are:
- Ignition state.
- Air bag warning indicator chime request communicated by the RCM to the IPC.
Belt-Minder(R)
The Belt-Minder(R) is configurable. To configure with a scan tool, refer to Information Bus. To configure without a scan tool, refer to Belt-Minder(R) Deactivating/Activating Service and Repair.
The Belt-Minder(R) feature supplements the current safety belt warning function and is enabled after the current safety belt warning is complete. The Belt-Minder(R) reminds the driver that the driver or passenger safety belt is unbuckled by intermittently and simultaneously sounding a chime and illuminating the safety belt warning indicator in the IPC once the vehicle speed has exceeded 9.7 km/h (6 mph). The Belt-Minder(R) remains active for 5 minutes from the time it is started. While activated, the Belt-Minder(R) chime provides a series of 6 chimes/safety belt warning indicator flash sequences consisting of a 1-second chime tone and safety belt warning indicator on/off state. The Belt-Minder(R) chime and the safety belt warning indicator sound and flash for 6 seconds, then the chime stops and the safety belt warning indicator remains on for 30 seconds. The IPC repeats the chime cycle for 5 minutes.
If the vehicle speed drops below 4.8 km/h (3 mph) once the Belt-Minder(R) chime has activated, the chime turns off and the safety belt warning indicator remains on. When the vehicle speed exceeds 9.7 km/h (6 mph) again, the Belt-Minder(R) chime resumes.
The IPC also provides a toll booth feature which allows the driver or passenger to unbuckle their safety belt after the safety belts were initially buckled. This feature provides 1 minute without warnings after the vehicle exceeds 9.7 km/h (6 mph) again with a safety belt unbuckled.
When a MyKey(TM) is in use, the driver cannot configure the Belt-Minder(R) off. Once the Belt-Minder(R) is activated, the Belt-Minder(R) continues to chime periodically and the audio system is muted until both the driver and passenger safety belts are fastened.
The Belt-Minder(R) warning chime inputs are:
- Ignition state.
- Driver or passenger safety belt warning chime request communicated by the Restraints Control Module (RCM) to the IPC through the HS-CAN.
Forward Collision Warning Chime
The forward collision warning chime warns that a forward collision potential has been detected or if the Head Up Display (HUD) module detects a forward collision warning system concern.
Once the forward collision system detects a possible forward collision, the HUD module flashes, the forward collision warning chime sounds, and the audio system is muted.
The forward collision warning system also provides a confirmation chime to inform the driver that the forward collision system configuration (chime or system on/off) has been changed.
The forward collision warning system and chime can be configured off using the message center switch. Refer to Fire Suppression System. When a MyKey(TM) is in use, the driver cannot configure the forward collision warning system or chime off.
The forward collision warning chime inputs are:
- Ignition state.
- Forward collision warning alert chime command communicated by the HUD module through the HS-CAN.
- Forward collision warning confirmation chime command communicated by the HUD module through the HS-CAN.
Door Ajar Warning Chime
The door ajar warning chime warns that a door or the luggage compartment lid is open or not fully closed. The chime sounds when any door or the luggage compartment lid becomes ajar while the ignition is in the RUN mode.
The door ajar warning chime stops sounding and resets when all the doors and the luggage compartment lid are closed, or the ignition is placed in the OFF mode.
The door ajar warning lamp/chime inputs are:
- Ignition RUN/START status.
- Door/luggage compartment ajar data communicated by the SJB to the IPC through the MS-CAN.
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 and the headlamp switch is in the PARK or HEADLAMP position with the ignition in the OFF mode and the key out (non-Intelligent Access (IA) vehicles only).
The headlamps on warning chime stops sounding when any one of the above conditions are removed.
The headlamps on warning chime inputs are:
- Ignition mode to the SJB.
- Key-in-ignition switch position to the SJB.
- Door ajar input from the driver door ajar switch to the SJB.
- Headlamp switch input to the SJB.
- Headlamps on chime request communicated by the SJB to the IPC through the MS-CAN.
Key-In-Ignition Warning Chime (Non-IA-Equipped Vehicles)
The key-in-ignition warning chime warns that the key is still in the ignition lock cylinder when the driver door is ajar. The key-in-ignition warning 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 key-in-ignition warning chime stops sounding when the driver door is closed, the key is removed from the ignition lock cylinder, or if the ignition switch is turned to the ON position.
The key-in-ignition warning chime inputs are:
- Ignition RUN/START status.
- Key-in-ignition switch position to the SJB.
- Door ajar input from the driver door ajar switch to the SJB.
- Key-in-ignition chime request communicated by the SJB to the IPC through the MS-CAN.
Key-In-Ignition Warning Chime (IA-Equipped Vehicles)
The key-in-ignition warning chime warns that the ignition is in the ACC mode and the driver door is ajar. The Remote Function Actuator (RFA) module monitors the ignition mode and door ajar status then provides an implied key-in-ignition state to the SJB. The SJB then sends a key-in-ignition chime request to the IPC over the MS-CAN.
The key-in-ignition warning chime inputs are:
- Ignition RUN/START status.
- Implied key-in-ignition signal to the SJB from the RFA module.
- Key-in-ignition chime request communicated by the SJB to the IPC through the MS-CAN.
The RFA module uses a Field-Effect Transistor (FET) protective circuit strategy for the key-in-ignition output to the SJB. FET is a type of transistor that when used with module software can be used to monitor and control current flow on module outputs. The FET protection strategy is used to prevent module damage in the event of excessive current flow.
Output loads (current level) are monitored for excessive current (typically short circuits) and are shut down (turns off the voltage or ground provided by the module) when a fault event is detected. A continuous DTC is stored at the fault event and a cumulative counter is started.
When the demand for the output is no longer present, the module resets the FET circuit protection to allow the circuit to function. The next time the driver requests a circuit to activate that has been shut down by a previous short (FET protection) and the circuit remains shorted, the FET protection shuts off the circuit again and the cumulative counter advances.
When the excessive circuit load occurs often enough, the module shuts down the output until a repair procedure is carried out. Each FET protected circuit has 3 predefined levels of short circuit tolerance based on the harmful effect of each circuit fault on the FET and the ability of the FET to withstand it. A module lifetime level of fault events is established based upon the durability of the FET. If the total tolerance level is determined to be 600 fault events, the 3 predefined levels would be 200, 400 and 600 fault events.
When each tolerance level is reached, the continuous DTC that was stored on the first failure cannot be cleared by a command to clear the continuous DTCs. The module does not allow this code to be cleared or the circuit restored to normal operation until a successful self-test proves that the fault has been repaired. After the self-test has successfully completed (no on-demand DTCs present), DTC U1000:00 and the associated continuous DTC (the DTC related to the shorted circuit) automatically clears and the circuit function returns.
When the first or second level is reached, the continuous DTC (associated with the short circuit) sets along with DTC U1000:00. These DTCs can be cleared using the module on-demand self-test, then the Clear DTC operation on the scan tool (if the on-demand test shows the fault corrected). The module never resets the fault event counter to zero and continues to advance the fault event counter as short circuit fault events occur.
If the number of short circuit fault events reach the third level, then DTC U1000:00 sets along with the associated continuous DTC. This DTC cannot be cleared and the module must be replaced.
Memory Feedback Feature Chime
The purpose of the memory feedback feature chime is to inform the driver that their preferences have been successfully programmed through the memory set procedure.
The memory feedback chime inputs are:
- Ignition state.
- Memory feedback chime request communicated by the Driver Seat Module (DSM) to the IPC over the MS-CAN.
Message Center Warning Chime
The message center warning chime feature is used to draw the driver's attention to the message center display to view a new warning message. The IPC provides a single one-second tone whenever a new warning message is displayed in the message center. If multiple warning messages are present, the IPC sounds a chime for each of the warning messages that are present.
Parking Brake Warning Chime
The parking brake warning chime warns that the parking brake is engaged when the vehicle is in motion. The parking brake warning chime sounds if the ignition is in RUN mode, the parking brake is engaged, and the vehicle speed is greater than 5 km/h (3 mph).
The parking brake warning chime stops sounding if the parking brake is released, the ignition is not in RUN mode, the vehicle speed is less than 4.8 km/h (3 mph), or after 90 seconds from the time the chime is activated.
The parking brake warning chime inputs are:
- Ignition state.
- Parking brake switch status communicated by the SJB to the IPC through the MS-CAN.
- Vehicle speed data communicated by the PCM to the SJB through the MS-CAN.
- Parking brake warning chime request communicated by the SJB to the IPC.
Perimeter Alarm Warning Chime
Perimeter alarm warning chime feature is to alert the driver of impending perimeter alarm activation
The perimeter alarm warning chime is used to alert the driver that the perimeter alarm is armed when the driver door is unlocked with a key. The warning chime is only functional when a key is used to unlock the driver door. If the key fob or keypad (if equipped) is used to unlock the door, the perimeter alarm is disarmed and the warning chime does not sound. The warning chime sounds for 12 seconds when the driver door is opened and turns off when the perimeter alarm is disarmed (either by using the key fob, keypad or turning the key to the ON position). After the 12-second warning chime duration, the warning chime stops sounding and the perimeter alarm activates, sounding the horn and flashing the turn signal lights.
NOTE: The perimeter alarm takes approximately 25 seconds to fully arm once the driver has locked the doors using the key fob or keypad.
The perimeter alarm warning chime inputs are:
- Ignition state.
- Perimeter alarm warning chime request communicated by the DSM to the IPC through the MS-CAN.
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 is changed from the OFF or ACC to the RUN or START mode.
The safety belt warning chime inputs are:
- Ignition state.
- Driver safety belt warning chime request communicated by the RCM to the IPC through the HS-CAN.
Service AdvanceTrac(R) Warning Chime
The service AdvanceTrac(R) warning chime warns that the ABS module has detected a fault condition in the AdvanceTrac(R) system. The SERVICE ADVANCETRAC message is also displayed along with the chime.
The service AdvanceTrac(R) chime sounds for approximately 2 seconds after an initial delay of 8 seconds following key ON. The AdvanceTrac(R) chime stops sounding when the ignition switch is turned from the RUN/START position to the OFF/LOCK or ACC position or when fault condition is repaired.
The service AdvanceTrac(R) warning chime inputs are:
- Ignition state.
- Service AdvanceTrac warning chime request communicated by the ABS to the IPC through the HS-CAN.
Turn Signal Left On Warning Chime
The turn signal left on warning chime warns that the turn signal has not been cancelled. The turn signal left 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 left on warning chime stops sounding if the turn signal is turned off or if the ignition is switched to the OFF or ACC mode.
The turn signal left on warning chime inputs are:
- Ignition state to the IPC and SJB.
- Turn signal on data communicated by the SJB to the IPC through the MS-CAN.
- Odometer count data communicated by the PCM to the IPC through the HS-CAN.
Turn/Hazard On Tone
Since the turn/hazard flasher is an electronic function of the SJB, the on/off sound that used to be present with standard bi-metal flashers is no longer present. To provide an audible sound and indicate that the RH/LH turn or hazard indicators are on, the IPC provides a tick-tock tone along with the visual turn signal indicators.
The turn/hazard on tone inputs are:
- Left turn indicator signal from the SJB to the IPC through the MS-CAN.
- Right turn indicator signal from the SJB to the IPC through the MS-CAN.