Intrigue V6-3.8L VIN K (1998)
Body Control Module: Initial Inspection and Diagnostic Overview
Body Control Module Diagnostic Information
BODY CONTROL MODULE (BCM)
The BCM uses information from other vehicle systems, such as the Powertrain Control Module (PCM), in order to perform some of its functions.
Before starting BCM diagnosis, read the circuit information and learn how the BCM operates and interacts with other vehicle system.
Understanding how the BCM operates will reduce diagnostic time, avoid misdiagnosis, and prevent unnecessary parts replacement.
Use a scan tool (Tech 2) to diagnose the BCM when specified in the diagnostic tables. A scan tool displays Diagnostic Trouble Codes (DTCs), the
status of BCM inputs and outputs, and commands BCM outputs on and off. Refer to Displaying DTCs for more information.
Become very familiar with the BCM capabilities and diagnostic features. These self-diagnostic features are referenced in the diagnostic tables and
are very useful in diagnosing non-DTC setting malfunctions as well.
Replace the BCM only when a diagnostic table specifically direct you to do so. BCM inputs and outputs are protected against shorts to battery or
ground. Therefore, do NOT replace the BCM after repairing a short in the wiring. After repairing the wiring, perform the BCM diagnostic system
check to verify the repair. Most malfunctions related to a vehicle system, such as the BCM, are traceable to faulty wiring, connectors and
terminals, and occasionally some other component. Refer to Body Control Module Diagnostic System Check for more information. The BCM is
a very reliable component and it is not likely the cause of the malfunction. Replacing the BCM before a complete diagnosis will usually result in a
recurrence of the original malfunction. See:
DIAGNOSTIC TROUBLE CODES (DTCS)
The BCM stores DTCs as current or history DTCs. If the BCM detects a malfunction, the BCM stores a DTC that corresponds to that particular
malfunction. The BCM does not send a message to the instrument cluster to display a message, such as turning on a warning indicator lamp. If the
BCM stores a current DTC and the malfunction is no longer present, some DTCs will remain current until the next ignition cycle. Other DTCs
change from current to history without requiring a new ignition cycle when the fault is no longer present. History DTCs are intermittent
malfunctions and must be diagnosed differently than current DTCs. Refer to Intermittents and Poor Connections for more information.
Intermittents and Poor Connections
Intermittent faults in electronic systems may be very difficult to detect and to diagnose accurately. 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 drive test, a good description of the complaint may be useful in locating an intermittent fault condition. Also,
perform tests while moving related wiring and connectors. This can often cause the malfunction to reoccur.
Faulty wires or connections cause most intermittent problems. When an intermittent condition is suspected, inspect the suspected circuits for these
conditions:
^
Poor mating of connector halves, or backed out terminals.
^
Improperly formed or damaged terminals.
^
Wire chafing.
^
Poor wire to terminal connections.
^
Dirty or corroded terminals.
^
Connector body damage.
History Diagnostic Trouble Codes (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. 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 Tech 2 scan tool. Read the
diagnostic aids and conditions for setting the DTC in each DTC table for more specific information. Perform a thorough inspection of all related wiring
and connectors pertaining to the history DTC that is stored.
The following conditions may result in intermittent BCM operation with no DTCs stored:
^
Any condition which results in the interruption of power to the BCM.
^
The battery voltage is out of range (below 9V or above 16V).
^
A loose or damaged ground.
System Check
