Principles of Operation

PRINCIPLES OF OPERATION

NOTE: The smart junction box (SJB) is also known as the generic electronic module (GEM).

The instrument cluster (IC) is a hybrid electronic cluster (HEC) that utilizes a microprocessor to control the gauge and indicator functions. Data is sent to the instrument cluster (IC) over the high speed controller area network (HS-CAN) bus lines and through hardwired circuitry to individual components such as the oil pressure switch, the parking brake switch and the ABS module. The instrument cluster (IC) acts as a gateway module by receiving information in one format and transmitting it to other modules using another format. For example, the instrument cluster (IC) receives the four wheel drive (4WD) data from the 4x4 control module over the HS-CAN and sends the 4WD status to the ABS module through hardwired circuitry. This enables communication with modules that are not on the HS-CAN.

NOTE: The parameter reset procedure must be carried out on passive anti-theft system (PATS) and non-PATS vehicles or a no-start condition may occur.

When installing a new instrument cluster (IC), it is necessary to upload the module configuration to the scan tool. Following installation of the instrument cluster (IC), download the module configuration from the scan tool into the new instrument cluster (IC). Refer to Information Bus (Module Communications Network) to carry out the programmable module installation (PMI). It is also necessary to carry out a parameter reset procedure whenever a new instrument cluster (IC) or PCM is installed. Programming and Relearning

Instrument Cluster (IC) Prove-Out
The instrument cluster (IC) carries out a display prove-out to verify that all instrument cluster (IC) controlled warning/indicator lamps and monitored systems are functioning correctly within the instrument cluster (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: