Diagnostic System Check - BCM

Body Control Module Diagnostic System Check:

Body Control Module Diagnostic System Check (Part 1 Of 2):

Body Control Module Diagnostic System Check (Part 2 Of 2):

CIRCUIT DESCRIPTION

IMPORTANT:
^ After performing a repair that requires clearing DTC(s) from the BCM, inspect the repair by operating the vehicle within the limits shown in Conditions for Setting the DTC. Operating the vehicle under these specifications will verify that the repair was completed properly.
^ Use the J 35616-A when probing electrical circuits in order to prevent damage to damage to electrical components and connectors. The J 35616-A is the ONLY recommended method of probing connectors, terminals, and Bussed Electrical Centers (BECs). The J 35616-A contains an assortment of flexible connectors used in order to probe connectors, terminals and BECs during diagnosis.
^ Do not use a test lamp in order to diagnose the BCM electrical systems unless you are specifically instructed by diagnostic procedures. Use the J 35616-A when diagnostic procedures require probing of connectors. Refer to Special Tools.
^ The Body Control Module (BCM) will withstand normal current draws associated with the vehicle operations. Do not overload any circuit.
^ When you test for opens or shorts, do not ground or apply voltage to the BCM circuits unless instructed to do so. Use a J 39200 Digital Multimeter (DMM) (or equivalent) in order to test these circuits. Test electrical circuits using a DMM while the BCM connectors remain connected to the BCM or to the recommended breakout box.
^ Do not remove or apply the voltage to the BCM when the key is in the RUN position. Always turn the key to the LOCK position when any of the following components are removed or connected:
- Battery cables
- Fuses
- Connectors
^ Whenever a BCM removal or replacement procedure is performed follow the instructions. Use the following guidelines when servicing the BCM system:
- Always DISCONNECT the BCM connector (BRN) FIRST.
- Always CONNECT the BCM connector (BRN) LAST.
^ The BCM may set codes when the ignition switch is in the OFF position. When you disconnect the electrical connectors from the BCM, the DTCs will set. The BCM may require 20 minutes (1216 seconds) in order to power down after the following conditions exist:
- The ignition switch is turned to the OFF position.
- The BCM is not receiving any active inputs.
- The BCM does not receive any active inputs for 20 minutes.

The body control module (BCM) diagnostic system check is a test that identifies a malfunction in the electronic system. The BCM diagnostic system check is the starting point for any BCM complaint. Understand and use the BCM diagnostic system check table in order to reduce diagnostic time and prevent unneeded replacement of components.