Corvette V8-5.7L VIN G (1997)
the starting point for any BCM complaint, and will direct you to the next logical step in diagnosing the complaint. The BCM is a very reliable
component and is not likely the cause of the malfunction. Most system complaints are linked to faulty wiring and connectors, and occasionally to
components. Understanding the computer system and using the tables correctly will reduce diagnostic time and prevent unnecessary parts
replacement.
DIAGNOSTIC AIDS
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The following conditions may result in an intermittent operation of the BCM with no DTC stored:
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Any condition which results in the interruption of power to the BCM
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Out of range battery or ignition voltage
Specification
Normal BCM operating voltage: 9.0-16.0 V
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A loose or damaged ground(s)
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An open or shorted serial data line
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An intermittent failure in the electronic system may be very difficult to detect and to accurately diagnose. The BCM test for different malfunctions
under different vehicle conditions. For this reason, a thorough test drive is often needed in order to repeat a malfunction. If the system malfunction
is not repeated during the test drive, a good description of the complaint may be very useful in locating an intermittent malfunction. Faulty
electrical connections or wiring causes most intermitting problems. When an intermitting condition is suspected, check the suspected circuits for
the following conditions:
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Poor mating of connector halves or backed out terminals
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Improperly formed or damaged terminals
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Wire chafing
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Poor wire to terminal connections
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Dirty or corroded terminals
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Damage to connector bodies
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Use the J 35616-A
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If the DTC is a history DTC, the problem may be intermittent. Perform the tests shown while moving related wiring and connectors. This can often
cause the malfunction to occur. Perform a thorough inspection of all related wiring and connectors pertaining to the history DTC stored. Refer to
Intermittents and Poor Connections. See: Intermittents and Poor Connections
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Exit all scan tool tests before cycling the ignition OFF to ON unless the scan tool instructions direct otherwise. Follow the operating instructions in
the scan tool operator's manual. Failure to follow these instruction may set DTCs, cause vehicle system malfunctions, set false DTCs, or cause scan
tool malfunctions.
TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table:
1. This test determines if communications can be established with the BCM.
2. This test checks for stored BCM DTCs.
3. This test determines whether communications can be established with other systems connected to the same serial data line.
4. This test checks for any open BCM power fuses.
5. This test checks the BCM power circuit. If the test light does not turn ON, there is an open in the BCM power circuit.
6. This test checks the BCM ground circuit. If the test light does not turn ON, there is an open in the BCM power circuit.
7. This test determines if an open is present in the serial data line between the BCM and the DLC (CKT 1037).
Intermittents and Poor Connections
Intermittent failures in electronic systems may be very difficult to detect and accurately diagnose. The Body Control Module (BCM) tests for different
malfunctions under different vehicle conditions. For this reason, a thorough test drive is often needed in order to repeat a fault condition. If the system
malfunction is not repeated during the test drive, a good description of the complaint may be useful in locating an intermittent malfunction. Faulty wires
or connections cause most intermitting problems. When an intermitting condition is suspected, inspect the suspected circuits for the following conditions:
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Poor mating of connector halves of backed out terminals
^
Improperly formed or damaged terminals
^
Wire chafing
^
Poor wire to terminal connections
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Dirty or corroded terminals
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Connector body damage
History DTCs are those indicating that the BCM has previously detected a malfunction. The reason could be either that the malfunction is intermittent or
that the system for which the DTC is set for is not currently being operated. For example, the rear defogger circuit does not operate until the BCM
detects engine RPM. For this reason, if the BCM displays history DTCs and the malfunction cannot be found easily, try clearing the DTCs and manually
operating the system that the DTC applies to using a scan tool. Read the Diagnostic Aids and Conditions for Setting the DTC in each DTC table for more
specific information.
History DTCs help in diagnosing intermittent fault conditions but do not necessarily indicate a faulty BCM. The BCM is a reliable component, and is not
the likely cause of the malfunction. Most system complaints are linked to faulty wiring and connectors, and occasionally to a component. Perform a
thorough inspection of all related wiring and connectors pertaining to the history DTC that is stored.
