Component Tests and General Diagnostics

INSTRUMENT CLUSTER

WARNING: To avoid serious or fatal injury on vehicles equipped with airbags, disable the supplemental restraint system before attempting any steering wheel, steering column, airbag, seat belt tensioner, impact sensor, or instrument panel component diagnosis or service. Disconnect and isolate the battery negative (ground) cable, then wait two minutes for the system capacitor to discharge before performing further diagnosis or service. This is the only sure way to disable the supplemental restraint system. Failure to take the proper precautions could result in accidental airbag deployment.

If all of the ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN or KOMBI) gauges and indicators are ineffective, be certain to check the instrument cluster fused B(+) circuit fuses as well as the instrument cluster fused B(+) and ground circuits for shorts or opens. Refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, details of wire harness routing and retention, connector pin-out information and location views for the various wire harness connectors, splices and grounds.

Conventional diagnostic methods may not prove conclusive in the diagnosis of the instrument cluster. In order to obtain conclusive testing of the instrument cluster, the Controller Area Network (CAN) data bus network and all of the electronic modules that provide inputs to or receive outputs from the instrument cluster must also be checked. The most reliable, efficient, and accurate means to diagnose the instrument cluster, the CAN data bus network and the electronic modules that provide inputs to or receive outputs from the instrument cluster requires the use of a diagnostic scan tool and the appropriate diagnostic information.

The diagnostic scan tool can provide confirmation that the CAN data bus network is functional, that all of the electronic modules are sending and receiving the proper electronic messages over the CAN data bus, and that the instrument cluster is receiving the proper inputs and responding with the proper outputs needed to perform its many functions.