Navigator 2WD V8-5.4L (2007)
It is very important to understand:
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where the input (command) originates.
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all the information (messages) necessary in order for a feature to operate.
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which module(s) receive(s) the input or command message.
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if the module that received the input (message) controls the output of the feature, or if it outputs a message over the CAN to another module.
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which module controls the output of the feature.
Instrument Cluster Messages
NOTE: Whenever a message is suspected as missing, confirmed by a missing message DTC, it is important to look for other symptoms that may also
be present in the instrument cluster and throughout the vehicle. Once a DTC is set in the instrument cluster it may be helpful to review the complete
message list available in Information Bus (Module Communications Network) 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.
The instrument cluster 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 message is missing the O/D
off status for less than 5 seconds and the O/D off indicator was ON (O/D cancelled), 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 instrument cluster 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 Instrument Panel, Gauges and Warning Indicators. for further descriptions 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.