Initial Inspection and Diagnostic Overview

A Diagnostic System Check - Body Control System (Part 1 Of 3):

A Diagnostic System Check - Body Control System (Part 2 Of 3):

A Diagnostic System Check - Body Control System (Part 3 Of 3):

SYSTEM DESCRIPTION
The Body Control Module (BCM) diagnostic system check identifies conditions that are associated with the BCM. The following test is the starting point for any BCM concern or complaint. The test directs you to the next logical step in diagnosing the complaint.

The BCM is a reliable component and is not likely to cause the malfunction.

The following items cause most system complaints:
^ Faulty wiring
^ Faulty connectors
^ Faulty components

Understand the computer system and use the tables correctly in order to achieve the following results:
^ Reduce diagnostic time
^ Prevent unnecessary parts replacement

DIAGNOSTIC AIDS
The following conditions may result in an intermittent operation of the BCM with no DTC stored:
^ Any condition which results in the interruption of power to the BCM
^ Out of range battery voltage specification. Normal battery voltage is 9-16 volts.
^ A loose or damaged ground(s).

It may be difficult to detect and accurately diagnose an intermittent failure in the electronic system. The BCM tests for the different malfunctions under different vehicle conditions. A test drive may cause a malfunction to repeat. If the system malfunction is not repeated during the test drive, a good description of the complaint may be useful in locating an intermittent fault condition.

Faulty electrical connections or wiring causes most intermittent problems. If you suspect an intermittent condition, inspect the suspected circuits for the following conditions:
^ Poor mating of the connector halves or backed out terminals
^ Improperly formed or damaged terminals
^ Wire chafing
^ Poor wire to terminal connections
^ Dirty or corroded terminals
^ Damage to the connector bodies

Use a J 35616-A for diagnostic procedures that require probing or testing a terminal. Use of the J 35616-A ensures the following results:
^ No damage occurs to the terminal.
^ The tool determines if contact tension is sufficient. DTC P1626 will set in the Powertrain Control Module (PCM) if the following conditions exist:
^ The ignition is in the RUN position.
^ The BCM is disconnected.

When the BCM diagnostics and repairs are completed, refer to Computers and Control Systems for additional information on the PCM related DTCs. Computers and Control Systems

TEST DESCRIPTION
The number(s) below refer to the step number(s) on the diagnostic table.
1. This step checks if the BCM identifies its BCM type.
2. This step checks if vehicle has correct BCM type installed.
3. This step checks for DTCs stored in BCM memory.
5. This step checks for a short to ground in CKT 40.
7. This step checks for a short to ground in CKT 1540
9. This step checks for a short to ground in CKT 39.
11. This step checks for a short to ground in CKT 443.
12. This step checks for an open in CKT 1550.
13. This step checks for an open in CKT 240.
14. This step checks for an open in CKT 1540.
15. This step checks for an open in CKT 39.
16. This step checks for a short to B+ in CKT 39.
17. This step checks for an open in CKT 443.
18. This step checks for a short to B+ in CKT 443.
19. This step checks for a short to B+ in CKT 1445.
20. This step checks for an open in CKT 1445.