Diagnostic System Check

Body Control Module (BCM):

Body Control Module (BCM) (Part 1 Of 3):

Body Control Module (BCM) (Part 2 Of 3):

Body Control Module (BCM) (Part 3 Of 3):

SYSTEM DESCRIPTION
The Body Control Module (BCM) Diagnostic System Check is an organized approach to identify problems associated with the BCM. The BCM Diagnostic System Check must be the starting point for any BCM-related complaint. The BCM Diagnostic System Check will direct you to the next logical step in diagnosing the complaint. The BCM is a very reliable component and it is not likely the cause of the malfunction. Most BCM system malfunctions are linked to faulty wiring, connectors, and occasionally to other vehicle components. Understanding the BCM and using the diagnostic tables correctly will reduce diagnostic time and prevent unnecessary parts replacement.

DIAGNOSTIC AIDS
^ Use a J 35616-A when probing or checking electrical connector terminals. The J 35616-A prevents terminal damage, plus checks for proper terminal contact tension.
^ If the BCM malfunction is intermittent, refer to Intermittent and Poor Connections. Intermittents and Poor Connections
^ Exit all Tech 2 scan tool tests before cycling the ignition switch to the LOCK position, unless indicated by the Tech 2 scan tool. Follow the Tech 2 scan tool user's manual. Failure to follow these instructions may set DTCs, cause vehicle system malfunctions, set false DTCs, or cause Tech 2 scan tool malfunctions. DTC P1626 will set in the Powertrain Control Module (PCM) when the ignition switch is in the RUN position with the Body Control Module (BCM) disconnected. When BCM diagnostics and repairs are completed, refer to the Engine Controls for additional information on PCM related DTCs. Powertrain Management

TEST DESCRIPTION
Numbers below refer to the step numbers on the diagnostic table.
2. Determines whether the Class II serial data link has a circuit malfunction or the BCM is not communicating with the scan tool.
4. Checks for a short to ground in circuit 2340.
5. Checks for an open in circuit 2340.
6. Checks for an open in circuit 1550.
7. Checks for an open in circuit 1037.
8. Checks for a faulty BCM.
15. Checks for BCM current DTCs stored in memory.
16. Checks for BCM history DTCs stored in memory.
19. Checks for an intermittent BCM system malfunction.