Ranger 4WD V6-3.0L VIN U (1997)
DTCs are reported to the NGS through the DLC. DTCs are cleared manually by the NGS or after a planned period of time not seeing the same DTC
(e.g., 80 start cycles) by the GEM.
Action that may be taken by continuous diagnostics are as follows:
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Manage the fault
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Store a diagnostic trouble code
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Illuminate a warning lamp
The GEM diagnostics mode has the ability to interface with you via the NGS. This diagnostic operation allows the best fault isolation capability. You
have the ability to communicate with the GEM subsystem when the NGS is in the diagnostics mode. Interaction with the GEM is achieved by the
following:
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Requesting the GEM to perform tasks (e.g., turn ON the wipers)
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Transmitting GEM control states (e.g., switch status)
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Physically interacting (e.g., connecting/disconnecting wires) with the vehicle hardware
The tester has a menu-driven user interface allow you the ability to run a specific diagnostic test. You can separate faults in the GEM through a
symptom-driven diagnostic process, exercising specific functional tests, or retrieving diagnostic trouble codes.
The majority of the GEM diagnostic strategy is in the GEM. The NGS requests the GEM for input and output status. It then sends commands to
actuate the output devices and has the GEM run diagnostic tests and report stored DTCs.
DETECTING AND STORING DIAGNOSTIC TROUBLE CODES
When the GEM energizes an external device, a short circuit condition can momentarily exist. This fault is not immediately stored as a diagnostic
trouble code since the fault can disappear after a few milliseconds. The GEM repeatedly attempts to energize the device for one second to confirm that
the fault still exists.
If the device is successfully energized before one second elapses, a diagnostic trouble code is not stored and fault management action is not taken. If
the fault continues after the predetermined fault time, a diagnostic trouble code is stored and appropriate fault management action is then taken.
DETECTING FAULTS IN THE GEM OUTPUT CIRCUITS
Battery shorts can only be detected when the device being controlled is actuated (e.g., relays, lamps or solenoids).
All faults are monitored continuously during the vehicle operation.
REPORTING TROUBLE CODES
Faults are displayed after the continuous DTCs and the On-Demand DTCs are retrieved. Continuous DTCs should be retrieved from the GEM before
an On-Demand Self Test is run. These DTCs are then compared against the diagnostic trouble codes retrieved after running an On-Demand Self Test.
CLEARING CONTINUOUS DTCs
Continuous DTCs must be cleared when the problem has been fixed. Trouble codes can be cleared by sending a request from the NGS to clear them.
AUTOMATICALLY CLEARING CODES
Automatic clearing of individual trouble codes is done when the fault is not present for 80 start cycles. These trouble codes are automatically cleared
after 80 start cycles.
TESTER-DEPENDENT DIAGNOSTIC CAPABILITY AND FAULT ISOLATION
The tester-dependent diagnostics allows you to communicate with the GEM through a tester connected to the DLC.
Running a diagnostic test may require the GEM to energize an output device. Some output devices might be limited to the amount of time that they
can be actuated. The tester can reactivate the device by exiting the diagnostic test and entering the test again. The GEM will not protect for enter/exit
condition of the tester.
During the tester-dependent diagnostics mode, the tester can only command the GEM to perform tests on disabled functions. A response is sent to the
tester if a diagnostic test request is made on a function that is not disabled.
The NGS can request the GEM to activate or deactivate an output device.
VEHICLE CONDITIONS FOR ON-DEMAND SELF TEST
During on-demand self-test the GEM disables all output functions.
On-demand self-test requires the following vehicle conditions:
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All doors are closed
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The ignition switch is in the RUN position
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The wiper control is in the OFF position and the wiper blades are parked
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The headlamps are off
